Wood properties.pptx

Unit - 6
Physical properties of Wood

Physical Properties:
• physical property is defined as a characteristic of matter that may be observed and measured
without changing the chemical identity of a sample.
• Physical properties are defined as, “The properties which are determined without any change in
size, shape, and chemical composition of wood.”
• The physical properties of wood are discussed as under;
i. Colour of wood
ii. Lustre
iii. Odour & taste
iv. Wood density
v. Specific gravity

i. Wood density:
• The density of a material is defined as the mass per unit volume at some specified condition.
• Wood density indicate the amount of actual wood substance present in a unit volume of wood
• For a hygroscopic material such as wood, density depends on two factors;
 the weight of the basic wood substance and
 the weight of the moisture retained in the wood.
• Wood density varies with moisture content and must be given relative to a specific condition in
order to have practical meaning.
• The density of wood is not a fixed value but varies with moisture content and its mass also changes
because the wood swells or shrinks depending on adsorption or desorption.
• Hence density of woods is determined by measuring the weight at a specific moisture content level.

i. Wood density:
• The density of wood depending on the tree growth environment, tree
species, moisture content, and wood anatomical characteristics
• Wood density is defined by the vessel size and number in the wood
where larger vessel size and higher vessel number would result in
low density
• In hardwoods, with a more complex anatomical structure,
differences in density derive from anatomical differences, such as
difference sin cell types and it's arrangements (ﬁbres, vessels, rays
and parenchyma cells)

ii. Wood Specific gravity
• Also known as relative density.
• The specific gravity is the ratio between the density of an object, and a reference substance.
• Usually our reference substance is water
• In simplest terms, specific gravity is the ratio of Density of the substance to the density of water.
• In case of wood, specific gravity is the ratio of density of the wood to the density of water.

ii. Wood Specific gravity
• The specific gravity can tell us, based on its value, if the object will sink or float in our reference
substance.
• Technically specific gravity is the measure of a wood’s density as compared to water.
Example:
• If specific gravity of the substance is 0.2, It means 20% of
the object is submerge in water and 80% float.

Utis: 44% submerge
ii. Wood Specific gravity…..
Sal: 880 kg/m3
Utis: 440kg/m3
Specific gravity of sal =
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒔𝒂𝒍
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓
Specific gravity of sal =
𝟖𝟖𝟎
𝟏𝟎𝟎𝟎
= 𝟎. 𝟖𝟖 = 𝟖𝟖%
Specific gravity of Utis =
𝟒𝟒𝟎
𝟏𝟎𝟎𝟎
= 𝟎. 𝟒𝟒 = 𝟒𝟒%
Sal: 88% submerge

Effects of earlywood and latewood in wood density
• Early in the growing season, cell division is fast and the
subsequent cell enlargement has a relatively long duration
• The wall-thickening phase is relatively short but the wall
thickness must be sufficient to minimize the risk of cell
implosion causing hydraulic failure.
• The resulting tracheids become large (earlywood cells)
and supply the bulk of the crowns’ water demand.
• Later in the growing season, cell division slows down, the
enlargement phase shortens and the wall-thickening phase
extends.

• Earlywood is porous, and made up of thin walled
cells, compared to latewood, which is influenced by
colder temperatures and drier conditions. As a result,
latewood is made of densely-layered, strong, thick-
walled cells.
• Tracheid diameter of earlywood cells to be
approximately twice that of latewood cells and the
cell wall thickness of earlywood tracheids to be about
½ that of latewood tracheid.

• Growth rings result from the difference in density
between the early wood (spring wood) and the late
wood (summer wood); early wood is less dense
because the cells are larger and their walls are
thinner.
• The specific gravity of latewood increased drastically
going from the pith until approximately the tenth ring
and then was relatively constant.
• Earlywood had less variation with age. The specific
gravity of earlywood declined during the first few
growth rings, and then it remained relatively constant

Unit - 7
Moisture Content of Wood

Moisture content (MC) in Wood
• The total amount of water in a piece of wood is called its moisture content (MC).
• The moisture content of newly sawn wood is usually 40-200%.
• In normal use the moisture content of wood varies between 8% and 25% by weight,
depending on the relative humidity of the air.
• Moisture content in wood is defined as the mass of water present in the timber divided by
the mass of the timber with all water removed, expressed as a percentage.
MC =
Green weight −Oven dried weight
Oven dried weight
* 100%
OR

Form of Water in Wood
Free Water: Not Chemically Bonded with cell wall,
contained in the cell cavities. It is comparable to water
in a pipe
Bound Water: Attached with cell wall by chemical
bonding (H- Bond). It is held within cell walls by
bonding forces between water and cellulose molecules.
Free water increase the weight but bound water
increase the volume of wood.

Hygroscopic Nature of Wood
• Hygroscopicity of Wood Hygroscopicity means the
ability to absorb or release water as a function of
humidity and temperature
• Wood shows hygroscopicity due to presence of –OH
group in cellulose (cell wall) of the plant cell.
• It soaks water very slowly, not very fast
• Hygroscopic behavior affects other properties of
wood
• It uptakes water vapor from the air and liquid water
as well

Wood cell
Basis of Shrinkage and Swelling of Wood
• As wet wood dries, free water leaves the lumens (cell cavities) first. (Free water resembles liquid in a
bucket. When you dump water out of a bucket, the bucket does not change shape).
• Similarly, wood does not shrink as it loses free water from the lumen.
• After all the free water is gone and only bound water remains, the cell has reached its fiber saturation
point (FSP).
• At this point, no water is present in the cell lumen, but the cell wall is completely saturated. It can hold
no more water between the microfibrils.
• Fiber saturation point is the point in drying wood at which all free moisture has been removed from
the cell itself while the cell wall remains saturated with absorbed moisture
• We can remove water from wood cells easily up to the FSP.

microfibrils
Basis of Shrinkage and Swelling of Wood
• As wood is dried further, bound water leaves the cell wall, and cells start to lose moisture
below the FSP.
• As water leaves and the microfibrils come closer together, shrinking occurs (Figure below).
• When moisture is added to wood, the process is reversed. First, water enters the spaces
between the microfibrils in the cell wall.
• Once the FSP is reached, excess moisture re-enters the wood lumens
• FSP for most wood species falls in the range of 25 to 30 percent MC

microfibrils
Equilibrium Moisture Content (EMC)
• Equilibrium moisture content (EMC) is the moisture level where the wood neither gains nor
loses moisture since it is at equilibrium with the relative humidity and temperature of the
surrounding environment.

Unit-8: Thermal properties of Wood
• Thermal properties of wood; thermal expansion, specific heat, thermal conductivity and
diffusivity.
• Change of temperature in wood under heating.
• Effect of moisture on thermal properties.
• Thermal properties of wood composites

• Thermal properties are those properties of a material which is related to its conductivity of
heat.
• In other words, these are the properties that are exhibited by a material when the heat is
passed through it.
Thermal Expansion:
• When heat is passed through a material, its shape changes. Generally, a material expands
when heated. This property of a material is called thermal expansion.
• The thermal expansion coefficients of completely dry wood are positive in all directions; that
is, wood expands on heating and contracts on cooling.” However, moisture fluctuations
impact dimensional movement of the wood at the same time.

Thermal Expansion:
• The measurement of wood thermal expansion at fixed values of moisture content (MC) is a
very difficult task, as MC varies with temperature.
• Weatherwax and Stamm measured the thermal expansion coefficients of a number of
American species and wood-derived products in the dry state.
• The authors reported the values of longitudinal, radial and tangential (αt) coefficients of
thermal expansion for two ranges of temperature variations, i.e., from 0 to 50 °C and from
− 50 to 50 °C.
• The coefficients showed a linear relation with density, but did not show significant changes
for both T ranges

Specific heat of wood
• Heat capacity or thermal capacity is a physical property of matter, defined as the amount of
heat to be supplied to an object to produce a unit change in its temperature
• The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of
the material when its temperature increases 1 °C.
• The SI unit of heat capacity is joule per kelvin (J/K).
• Wood has a higher specific heat than metal, so it takes more energy to heat a wooden handle
than a metal handle. As a result, a wooden handle would heat up more slowly and be less
likely to burn your hand when you touch it.

Thermal Conductivity:
• The ability of the wood sample to conduct heat is called the Conductivity.
• It is the transfer of energy in the form of heat due to a difference in temperature within a material or
between materials.
• Wood conduct heat comparatively slowly (due to the porous nature), it is one of the property due to
which timber is used in building material, furniture, and other materials.
• A wooden wall allows much less heat to pass through it than iron, concrete, brick or stone wall.
• The rate of flow of heat within a wood depends upon the direction of fiber/ grain, moisture content and
density of the wood material.
• Under the similar condition, 2-3 time more heat is conducted parallel to the grain as compared to
across the or perpendicular to the grain

Factor Affects the Thermal Conductivity
• The heat conductivity of wood is dependent on a number of factors. Some of the more
significant variables affecting the rate of heat flow in wood are the following:
density of the wood(thermal conductivity declines as the density of the wood decreases)
moisture content of the wood;
direction of heat flow with respect to the grain:
kind, quantity, and distribution of extractives or chemical substances in the wood. such as
gums, tannins, or oils:
relative density of springwood and summer-wood
proportion of spring-wood and summerwood in the timber;
defects, like checks, knots, and cross grain structure

Thermal Conductivity Equation
• This equation is called Fourier's Law for heat conduction, or the thermal conduction equation.
This is what it looks like:
Q represents the transfer of heat in time t
k represents the coefficient of thermal conductivity of the material
A is the area through which the heat is flowing
ΔT is the difference in temperature between the materials or within the material
d is the thickness of the material

Thermal Conductivity

Thermal Diffusivity
• Thermal Diffusivity is defined as the characteristic feature of a wood substance to show how
fast a wood material can absorb heat from its adjoining environment.
• A measure of how quickly a material can absorb heat from its surroundings.
• Thermal diffusivity is the thermal conductivity divided by density and specific heat capacity
at constant pressure.

Effect of Moisture Content on Thermal Properties of Wood
• Thermal conductivity is highest with higher moisture content
• The heat capacity of wood that contains water is greater than that of dry wood
• When moist wood is heated, it tends to expand because of normal thermal expansion and to
shrink because of loss in moisture content
• Wood at intermediate moisture levels (about 8% to 20%) will expand when first heated, and
then gradually shrink.

Thermal Properties of Other Wood Components
• Thermal conductivity values for oven-dried particleboards is lower than that of solid wood
due to the diminished contact among adjacent wood particles in the panel
• Thermal conductivity of a composite material depends on the fiber, resin materials, fiber
volume fraction, orientation of the fiber, direction of heat flow and operating temperature.
• Thermal conductivity of composites is anisotropic in nature.
• While the thermal conductivity information on wood species is a function of moisture content
and density
• The moisture content of wood-based materials containing fire retardants, preservatives, and
other volatile materials may be more difficult to measure if the wood product is heated in an
oven.

Unit-9
• Dimensional changes on heating green wood.
• Effect of dry and wet heat on wood
• heating in presence or absence of air on strength and dimensional
stability.

Dimensional changes on heating green wood
• Hygroscopic materials such as wood and other lignocellulosic material change their
dimensions with fluctuations in relative humidity.
• Therefore, determination of moisture content of wood products before they are used is an
important task. Based on the current moisture content of wood and its surrounding
conditions, dimensional changes in wood will take place, influencing its effectiveness as
a construction material.
• Hence dimensional changes on heating is the increase, or decrease, of the size (length,
area, or volume) of a wood due to a change in temperature.

• When the moisture content of green wood is reduced below the fiber saturation point, the
wood will shrink in both the tangential and radial directions and decrease in volume.
• Under normal temperature conditions the extent to which swelling or shrinking takes
place with moisture changes below the fiber saturation point will depend largely on the
density of the wood and the change in moisture content.
• Dimensional changes, shrinkage, and swelling in wood take place below the fiber
saturation point (FSP).

• Tangential dimensional change has the highest rate of change due to parallel orientation
of microfibrils along the axis of the cell wall. Shrinkage in the radial direction is the
second largest, while longitudinal shrinkage is negligible for most practical applications.
• Shrinkage or swelling (dimensional change %) = Change in dimension or volume ÷
Initial dimension or volume x 100
• The higher the density of wood, the greater is its shrinkage and swelling, because denser
(heavier) woods contain more moisture in their cell walls

There are following condition of heating wood
• Wet Heating
• Dry Heating
• Heating wood in the Absence of Air

Dry & Wet heating of wood
• Dry heating takes place at high temperature under dry air while moist heating takes place at
high temperature and pressure generated by the steam of water.
• Heating has been shown to improve the dimensional stability, hygroscopicity and decay
resistance of wood, though it weakens wood’s mechanical properties
• Boyce found that dry heat at 212° F. or steam heat at 250° F., applied to air-dried heartwood
for 20 minutes, had no measurable effect on the decay resistance.
• Hemicellulose, amorphous cellulose, and lignin are subject to degradation or modification,
and the extractives evaporate or polymerize
• Thermal modification alters the chemical properties of wood, making heat-treated wood
more resistant to decay.

• Mass loss of wood due to its thermal degradation is one of the most important features in
dry heating treatment and it is commonly referred to as an indication of its quality of
treatment.
• It has been found that there is mass loss (ML%) along with heat treatment & depends on
wood species and process conditions such as drying step, heating medium and treatment
intensity (couple temperature - duration)
where m0 and m1 are the masses (g) before and after heat treatment, respectively.

• As wood reaches elevated temperatures, the different chemical components undergo the
thermal degradation that affects the performance of wood.
• The extent of the changes depends on the temperature level and length of time under
exposure conditions. Permanent reductions in strength can occur at temperatures >65 °C,
with the amount depending on the temperature, pH of wood, moisture content, heating
medium, exposure period, and species.
• Strength degradation is likely to be due to depolymerization reactions involving no
significant carbohydrate weight loss.

Heating wood in the Absence of Air
• When wood is heated above 270° C it begins a process of decomposition called
carbonization.
• If air is absent the final product, since there is no oxygen present to react with the wood, is
charcoal. This is the well known enothermic reaction which takes place in charcoal burning.
• When the wood is dry and heated to around 280°C, it begins to spontaneously break down
to produce charcoal plus water vapour, methanol, acetic acid and more complex chemicals,
chiefly in the form of tars and non-condensible gas consisting mainly of hydrogen, carbon
monoxide and carbon dioxide.

Heating wood in the Absence of Air
• Wood that is subject to rapid thermal decomposition in the absence of oxygen is known as
pyrolysis. This process produces bio-oil liquids, gases, and char.
• Gasification occurs when wood is subject to high temperatures in a furnace. These
temperatures range between 1112 and 1832°F (600–1000°C) and is a special combustion
process due to the inclusion of a limited amount of oxygen and/or steam.

Unit-10
Electrical Properties of the Wood

Electrical Properties
• Electrical properties are ability pf the object to conduct electrical current
• Electrical properties of wood are measured by its resistivity, or specific resistance
or by its reciprocal, conductivity
Electrical resistance
• It is the opposition offered by a conductor to the flow electric current through it.
• SI unit ohm (abbreviated Ω),

Electrical resistivity
• Electrical resistivity is a fundamental property of a material that measures how
strongly it resists electric current.
• Electrical resistance of a conductor of unit cross-sectional area and unit length is
called electrical resistivity.
• SI unit(ohm meter)

Electrical Conductance (G)
• Conductance is define as the reciprocal of resistance.
• The SI unit of conductance = 1/ (The SI unit of resistance) = 1/Ω = Ω-1 = Siemens.

Electrical Conductivity
• Conductivity is define as the reciprocal of resistivity.
• The SI unit of conductivity = siemens per meter

Electrical Properties of Wood
• Electrical properties are their ability to conduct electrical current
• Electrical properties of wood are measured by its resistivity, or specific resistance
or by its reciprocal, conductivity
Electrical Conductivity & Resistivity of Wood
• The electrical conductivity of wood varies slightly with applied voltage and
approximately doubles for each temperature increase
• The electrical conductivity of wood or its reciprocal, resistivity, varies greatly with
moisture content, especially below the fiber saturation level.
• The electrical conductivity increases (resistivity decreases) by 10^10 to 10^13
times as moisture content increases from oven dry to the fiber saturation point.

Electrical Conductivity & Resistivity of Wood
• The resistivity is about 10^14 to 10^16 ohm-meters for oven-dry wood, and 10^3 to
10^4 ohm meters for wood at fiber saturation.
• For example, the electrical resistance for Douglas Fir varies with moisture content
as shown in a table below:

Factors Affecting the Electrical Properties
i. Moisture Content of Wood:
• The resistivity decreases rapidly by an approximate factor of three for each percentage moisture
content increase up to the fiber saturation point. at the fiber saturation point it becomes
approximately that of water alone, i.e., 105 to 106 ohm- centimeters.
ii. Temperature of wood
• Decrease in the resistivity with increasing temperatures.
iii. Grain direction
• In general resistivity across the grain is from 2.3 to 4.5 times greater than that along the grain for
conifers and from 2.5 to 8.0 times greater for hardwoods.
iv. Wood species:
• A variety of woods are known to occur in nature. Amongst these, all have different structures and
compositions.

Dielectric vs Insulator
Dielectric vs Insulator
• Dielectric material are those object that actually does not conduct electricity. They are
insulators having very low electrical conductivity.
• Dielectric is the material that can store electric charges or they are the materials in which
an electric field can develop with the minimum loss of energy.
• But, Insulator is the material that has low or zero electrical conductivity and they can
create obstruction in the flow of electric
• So we have to know the difference between dielectric material and insulating material.
The difference is that insulators block the flow of current but the dielectrics accumulate
electrical energy.

Dielectric Properties of Wood
• Wood acts as an insulator as it does not let the electric current pass through it.
• Wood is made up of a number of molecules combined together. The electrons associated
with the atoms of these molecules are bound very tightly and are not available to move
and conduct electricity.
• Thus, wood behaves as an insulator by not conducting electricity owing to the absence of
free charge carriers inside it and electrons are bound and associated with the nearest
atom.
• A dielectric (or dielectric material) is an electrical insulator that can be polarized by an
applied electric field and able to conduct the some amount of electricity.

Dielectric Properties of Wood
• The positive charges shift slightly towards
the direction of the electric field while the
negative charges shift slightly in the opposite
direction indicating an electric polarization.
• Interior charges cancel the each other and
equal and opposite charges are induces on the
opposite face of dielectric.
• polarization reduces the electric field within
the dielectric material. We can say that wood
conducts electricity and is a poor conductor.

Conclusion
• Wood does not conduct electricity as it is made up of different types of molecules in
which the atoms have their electrons strongly bound to their nucleus. As there are no
charge carriers available, the flow of charge is not possible.
• Wet wood conducts electricity owing to the presence of water and dissolved salts and
minerals. The ions present act as charge carriers and help in the conduction of electricity.
• The value of electrical conductivity for dry wood is around 10-16 to 10-14 while, that of
wet wood lies between 10-4 and 10-3 S/m.
• The electrical resistivity of dry wood is around 1×10^14 to 10^16 while, that of damp
wood is around 10^3 to 10^4 Ω m.

Unit-11
Response of defects to stress waves in timber.
Sound transmission and
Acoustics in buildings.

Unit-11
Stress Wave:
• A stress wave is a form of acoustic wave that travels at finite
velocity in a solid
• Sonic stress waves, commonly referred to simply as stress waves,
are those with frequencies within the audible range. Ultrasonic
stress waves are inaudible, having frequencies above 20,000 Hz.
• The most commonly used wave form is the longitudinal, or
compression, wave in which particles oscillate in the same
direction as the wave propagation. Transverse waves cause
particle oscillation perpendicular to the direction the stress wave
is moving.
Longitudinal wave
Transverse wave

Unit-11
Stress Wave in Forestry:
• The use of stress waves in non-destructive testing is based
on the propagation of sound waves through material and is
widely used for detecting interior voids and deterioration in
structural members, as well as for mechanical property
measurement.

Unit-11
Response of defects to stress waves in timber
• For the detection of voids and defects, wavelengths play a key role
• In general, stress waves travel faster in sound and high quality wood than in deteriorated
and low quality wood.
• In general, defects that are smaller than half the wavelength of the induced signal cannot
be detected by stress wave investigation

Unit-11
Response of defects to stress waves in timber
i. Response of decay and defect on stress wave velocity
• As wood deteriorate, their hardness is reduced. Wave velocity is proportionally linked to the
square root of the material hardness in which it is induced.
• Slower velocities or a longer transient time when compared to sound material indicate possible
deterioration.

Unit-11
Response of defects to stress waves in timber….
ii. Response of decay and defect on stress wave
attenuation
• Deterioration can be identified by the degree of stress
wave attenuation.
• In a degraded wood the amplitude of the waves will
decrease at a more rapid pace as energy is lost at a
higher rate.

Unit-11
Response of defects to stress waves in timber….
ii. Response of decay and defect on stress wave
frequencies & wavelength
• Plots of the frequency spectrum can be used to detect
and quantify the amount and distribution of timber
deterioration.
• The decay wood produces longer wavelength.
wavelength is inversely proportional to frequency of
the wave: waves with higher frequencies have shorter
wavelengths, and lower frequencies have longer
wavelengths.

Unit-11
Acoustics property of material
• Acoustical properties are those that govern how materials respond to sound waves.
• Sound energy is captured and adsorbed.
• It has a low reflection and high absorption of sound.
• Higher density improves the sound absorption efficiency at lower frequencies.
• It controls the sound and noise levels from machinery and other sources for
environmental amelioration and regulatory compliance.
• Acoustic material reduces the energy of sound waves as they pass through.
• It suppresses echoes, reverberation, resonance and reflection.

Unit-11
Sound transmission (Acoustics property) of wood
• Wood interacts with sound in different ways. It can
absorb, produce and amplify sound signals. For these
reasons, wood is an ideal material for musical
instruments and other acoustic applications, including
architectural ones.
• When it comes to auditorium’s and performance
spaces, such as concert halls, classrooms and lecture
theatres, wood is often chosen over steel, concrete
and glass to produce some of the most rewarding
acoustic spaces for performers and audiences.

Unit-11
Sound transmission (Acoustics property) of wood
• Increasing the MC level to fibre saturation point (FSP) causes the velocity of acoustic
waves to decrease.
• The wood’s grain direction affects wood acoustic impedance. When the acoustic signal is
emitted along the grain in wood, the acoustic impedance is good, whereas for across the
grain acoustic signal very bad.
• The best acoustic guitars in the world have historically been made from specific types of
wood, such as spruce, cedar and rosewood.
• “Low density, high Young’s moduli [higher strength], and low damping (lower decay rate)
contribute to high values of Loudness (L) index ,” which are usually a desirable quality in
an instrument.

Unit-11
• Building or architectural acoustics is the all aspects of sound and vibration in buildings.
• In buildings, Acoustic comfort is realized when a person’s activity is not disturbed by
noise and their hearing does not suffer.
• All types of buildings are subject to four types of sounds requiring mitigation:
Airborne sound (speech, stereos)
Impact sound (footsteps, falling objects)
Flanking sound (airborne and impact sounds emitting through tiny cracks and holes)
Sound reverberation caused by reflection off surfaces

Unit-11
• Building or architectural acoustics is the all aspects of sound and vibration in buildings.
• In buildings, Acoustic comfort is realized when a person’s activity is not disturbed by
noise and their hearing does not suffer.
• Buildings constructed with satisfactory acoustics are characterized by the control of the
transmission loss of sound through the construction elements, the absorption of sound
within a space, and the separation of noise sources from quiet spaces.
• Hence, Solid wood and some wood-based composites can be considered as acoustic
materials because of their ability to absorb an important amount of incident sound in order
to reduce the sound pressure level or the reverberation time in a room

Unit-11
Use of wood as an acoustics in buildings.
• Wood and wood-based composites are basic building materials and acoustic insulators
used for floors, ceilings, and walls, for the reduction of indoor and outdoor noise
Wood acoustics for noise control

Unit-11
Use of wood as an acoustics in buildings.
Wood acoustics for noise control

Unit-12
• Shear forces and bending moments, stresses in beams, beam deflections.
• Standard test on timber specimen: bending, compression parallel and perpendicular
to the grain, hardness, shear, tension parallel and perpendicular to the grain,
cleavage , nail and screw pulling, brittleness

Beam
• The beam is defined as the structural member which is used to bear different loads. It
resists the vertical loads, shear forces and bending moments.
Types of Beam
i. Cantilever Beam

Beam
ii. Simply Supported Beam
iii. Overhanging Beam

Beam
iv. Fixed Beam
v. Continuous Beam

Shear Force
• Algebraic sum of all the vertical forces
at any section of the beam, to the right
or to the left of the section is known as
shear force.
• It is shortly written as SF
• Let us suppose a cantilever beam with
following load in figure
10N
20N
30N
R= 60N
10N
10N
X'
X

Shear Force
• Algebraic sum of all the vertical forces
at any section of the beam, to the right
or to the left of the section is known as
shear force.
• It is shortly written as SF
following load in figure
30N
30N
10N
20N
30N
R= 60N X'
X

Share Force
• At any section in a beam carrying transverse loads the shearing force is defined as the
algebraic sum of the forces taken on either side of the section.
• Shear force at any section is resultant algebraic sum of transverse force either to the left of the
section are right of the section
• Sear force is an initial force acting parallel to the surface of cross section required to
maintained free body equilibrium either to left or right side of section.

Sign Convention for Shear Force
R = Right side
U = Upward direction
N = negative
X
X'
X
X'
LHS RHS
NEATIVE
POSITIVE

Moment
• The moment of a force is a measure of its tendency to cause a body to rotate about a specific
point or axis.
• Moments are usually defined with respect to a fixed reference point.
It is the turning effect produced by a force, on the body, on which it acts.

Bending Moment
• A bending moment (BM) is a measure of the bending effect that can occur when an external
force (or moment) is applied to a structural element.
• This concept is important in structural engineering as it is can be used to calculate where, and
how much bending may occur when forces are applied.
• The most common structural element that is subject to bending moments is the beam, which
may bend when loaded at any point along its length.

Sign Convention in Bending Moment
• Clockwise moments due to loads acting to the left of the section are assumed to be +ve, while
anticlockwise moments are taken –ve

Bending Moment Calculation
• Algebraic sum of the moments of all the
forces acting to the left or right of the
section is known as bending moment.
• It is shortly written as BM.
following load in figure. Let us take a
section of beam at x & x'
• Now Bending moment at the section is;
p3
p2
p1
Ra
d
d2
d1
X'
X

Bending Moment Calculation
• Let's take the left of the section X X'
• BM = Ra*d1- p1*(d1-d2)
p1
Ra
d2
d1
X
X'

Stress in beam
• The stress in a structural element is the internal force divided by the area of the cross-section on which it
acts. Stress is therefore internal force per unit area of cross-section; conversely internal force can be
regarded as the accumulated effect of stress
• When a beam is loaded with external loads, all the sections of the beam will experience bending
moments and shear forces.
• Mathematically, share stress is;
T =shear stress
F =applied force
A=cross-sectional area
F

Bending Stress
• Beams are stressed when they bend because the action of bending causes an elongation on
one side, resulting in tension, and a shortening on the other side, resulting in compression. By
exaggerating the curvature of the beam as it bends, this elongation and shortening can be
visualized. Exactly where the tension and compression are depends on how the beam is
loaded and how it is supported.

Deflection of Beam
• The deflection at any point on the axis of the beam is the distance between its position before and
after loading.
• When a structural is loaded may it be Beam or Slab, due the effect of loads acting upon it bends
from its initial position that is before the load was applied. It means the beam is deflected from its
original position it is called as Deflection.
• It is denoted by 'y'
• Deflection at the support is always zero
• In the given figure, after the load 'w' is applied to the center of the beam, it is deflected downward by
'y' distance called deflection of beam.
A B
W
Y

Standard test on Timber Specimen
• Bending
• compression, parallel and perpendicular to the grain
• hardness, shear, tension parallel and perpendicular to the grain,
• cleavage , nail and screw pulling, brittleness.

Standard test on Timber Specimen
• A standardized test is a test that is administered and scored in a consistent, or "standard", manner.
Standardized tests are designed in such a way that the interpretations are consistent and are
administered and scored in a predetermined, standard manner.
• Standard test on Timber Specimen cover the determination of various strength and related properties
of wood by testing small clear specimens.
• These test methods represent procedures for evaluating the different mechanical and physical
properties, controlling factors such as specimen size, moisture content, temperature, and rate of
loading.

Bending test of Timber Specimen
Test specimens
 Structural bending tests shall be made on specimens not
less than 350 cm in length, not less than 20 cm in depth and
not less than 15 cm in breadth.
 Actual width and depth at 15 cm intervals shall be recorded
correct to the nearest millimeter.
 For non-rectangular beams and beams of non-uniform
cross-section, data shall be recorded in such a way as to
obtain the exact size and shape at any cross-section.

Bending test of Timber Specimen
Bending test
 Bending strength is determined by applying a load to the
center of a test piece supported at two points.
 The bending strength of each test piece is calculated by
determining the ratio of the bending moment M, at the
maximum load Fmax, to the moment of its full cross-
section.
 Note down the maximum deflection and the maximum
load.

Compressive Strength of Wood
• When a material is loaded in compression, the maximum
load it can withstand without crushing or rupturing is called
its compressive strength.
• For a wooden sample, anticipatingly, the failure will be
brittle, and the material will fail without prior warnings.
However, the peak load that the wooden sample bears, also
depends on the orientation of its grains relative to the line
of action of externally-applied compressive load.

Compression of wood Parallel to grain
• When a compressive load is applied on a wooden sample such that the line of action of the external load and the
orientation of the grains become parallel, the wooden sample shows a relatively high compressive strength.
• Investigating the stress-strain relationship unveils that, the grains of the wooden sample act as separate columns
and each column contributes to bearing the applied load. Therefore, if a particular grain column fails or gets
malformed, the others play their part in withstanding the crushing load.
Failure Patterns

Compression of wood Perpendicular to grain
• When the applied loading is perpendicular to the grains of the wooden sample, the sample fails at a
relatively less load value. This is because any malformed grain reduces the overall load-bearing
capacity of the specimen.
Failure Patterns

Apparatus of Compression testing
• 500 kN Universal Testing Machine, to load the sample
in compression till its rupture
• Wooden cubes
• Deflection dial gauges, to determine the corresponding
value of strain with each load increment
• Vernier Caliper, to measure the dimensions of wooden
cubes, including their length, breadth, and height.

Test Procedure
• Measure the dimensions of the wooden sample using a vernier caliper.
• Place the wooden sample in the universal testing machine such that the grain fibers are parallel to the applied
compressive load.
• Attach the deflection dial gauges to the sample.
• Start loading the sample in compression.
• Note down the deflection reading from the dial gauges for each regular load increment.
• When cracks begin to appear, remove the deflection gauges and load the sample to failure. Note down the peak
or crushing load.
• Using the peak load and contact area, calculate the compressive strength of the wooden cube.
• Calculate the stress and strain values and plot a graph between them to determine the modulus of elasticity and
modulus of stiffness.
• Repeat the above procedure by orienting the sample in such a way that the grain fibers are perpendicular to the
applied load.

Wood Hardness Test
• Hardness refers to properties of solid materials that give them resistance when a force is applied.
• Many different species of wood that are of many different hardness levels are used in the
manufacturing
• Testing Methods:
Janka Wood Harness Testing
Brinell Wood Hardness Tester Methods

Janka Wood Hardness Testing
• The Janka hardness test method measures the amount of force required to
embed a 0.444 inch steel ball to one-half of its diameter in wood. It is
known as one of the best measures of the ability of a wood species to
withstand denting and wear

Brinell Wood Hardness Tester Methods
• The Brinell hardness test method measures the effect of pressing a small steel ball (with a
diameter of 10mm) similar to high-heels or furniture legs, into the flooring with 220.5 lbs
(100KN) of fixed force.
• More than 50 depressions are made on several samples of the wood. The diameter and depth f the
depressions are carefully measured to determine the hardness.
• This testing method is the most relevant and realistic method to determine surface hardness of
wood floors.

Testing of Wood Tension
• Tensile testing is a destructive test process that provides information about the tensile strength,
and ductility of the object.
• It measures the force required to break a composite or plastic specimen and the extent to which
the specimen stretches or elongates to that breaking point.

Testing Procedure of Wood Tension
• The tensile tester comes with a clamper having gripping jaws. These
jaws are meant to hold the sample.
• The sample is specially prepared for the testing. The sample is gripped
in the jaws. According to the testing standards, the load to be applied is
selected. Once the parameters are set, the upper plate of the machine
starts to move in an upward direction, while the lower plate will remain
stationary.
• The machine will keep on pulling the sample until it fractures. Once the
sample breaks, the machine stops itself. This is called over travel
protection. There are different standards applicable to check the tensile
strength of wood. But the most popularly followed is ASTM D143..

Testing of Wood Tension
• The tensile strength of wood is extremely high parallel to the grain and extremely low
perpendicular to the grain.
Along grain tension Across grain tension

Testing of Wood Cleavage
• Wood cleavage: splitting or separation of wood fiber
• The wood cleavage test is a very simple test to perform; only
concerned with the maximum tensile cleavage load sustained by the
wood specimen.
• Tensile load is applied to the wood specimen at a constant rate of
crosshead displacement, until the specimen breaks, measuring only
the maximum force reached.
• Equipment: ASTM D143 | BS 373

Nails and Screw Pulling
• Nails are often preferred for structural joining, including framing walls, because they are
more flexible under pressure, whereas screws can instant.
• To test the various loads and ways in which nails and screws fail, they are tested in tension
using withdrawal and pull-through tests and in shear using lateral movement tests.

Nails and Screw Pulling test
• The specimens were prepared according to TS 6094 standards. The measurements of the
specimens were 5×5×15cm and for all of the directions and for all of the wood species.
Moreover, the specimens were conditioned at 20±2°C and 65±2% relative humidity to
adjust their equilibrium moisture content as 12%.
• Nail measurements were 2.5mm diameter and 50 mm length, screws were 4×50mm
• Finds the maximum screw withdrawal resistance value
• In all tests the withdrawal strength of screw was found higher than that of nail

Unit-13
• Role of moisture on elastic and shrinkage: directional shrinkage and calculation of fiber
saturation point.
• Testing of specialized wood products, performance tests and method of evaluation for door
shutters, Joinery, furniture, packing cases, tool handles, agricultural implements and sports
goods.

Elasticity
Elasticity is the ability of an object or material to resume its normal shape after being stretched or
compressed.
• A body which regains its original state completely on removal of the deforming force is called
perfectly elastic.

Stress & Strain
Stress: It is the internal resistance of a material to external force without breaking or yielding.
Stress =
𝑭𝒐𝒓𝒄𝒆
𝑨𝒓𝒆𝒂
N/m2
Strain: Also known as deformation. Strain is the change in the dimensions of a body due to the
effect of stress.
Shear force

Modulus of Elasticity
• The modulus of elasticity is simply the ratio
between stress and strain.
• The modulus of elasticity is also known as Young’s
modulus, named after scientist Thomas young.
• Denoted by symbol 'E'.
• The modulus of elasticity shows the rigidity of the
material to resist axial deformation.

Role of moisture on elastic property of wood
• As an anisotropic bio-porous material, wood largely
depends on the moisture content and grain direction
for its mechanical properties
• It is well known that moisture content influences the
strength and stiffness of small clear wood specimens
subjected to bending. Strength and stiffness increase
with a decrease in moisture content
• For material with a strength of more than 8000 p. s. i.
(55, 200 kN/m2 ) the moisture content mostly
influence the elasticity.
• Hence higher the moisture content lower will be the
elastic properties.

Role of moisture on Shrinkage of wood
• Wood shrinks when it dries and swells when it becomes wet. These dimensional changes vary with
the species and the orientation of the wood fibers
• When wood dries from its green condition, little or no shrinkage occurs until the moisture content
falls below the fibre saturation level. At this level, all free moisture has been released from the cell
cavities, leaving only the cell walls saturated
• As the cell walls continue to release moisture, the wood shrinks almost in direct proportion to its
moisture loss. That is, for each percentage drop in moisture content, the wood shrinks by about
1/30 of its total potential shrinkage.
• The moisture level of the wood will eventually reach equilibrium with that of the surrounding air

Directional Shrinkage of wood
• Wood shrinks (or swells) not only tangentially and radially, but longitudinally as well.
Tangential shrinkage (concentric to the growth rings) is approximately twice the radial shrinkage
(perpendicular to the growth rings).
• The average tangential shrinkage of spruce from the fibre saturation level to the oven-dried state
is 7 to 8%, while the average radial shrinkage is about 4%. The longitudinal shrinkage for most
species over this moisture range, however, is only 0.1 to 0.2%
• Greater longitudinal shrinkage can occur if the wood is badly cross-grained or contains juvenile
or compression wood.

Calculation of Fiber Saturation Point
• The term fibre
saturation point (FSP)
was introduced by
Tiemann [1906] in the
20th century, in
connection with his
work on strength-
moisture relation

• In most practical, the easiest way to check the moisture content of a
piece of wood is to simply use a moisture meter.
• As piece of wood dries, it first loses its free water and dips below the
FSP (fiber saturation point). This FSP corresponds to roughly 30%
MC in most wood species. (The FSP may be roughly ±3% MC
depending on the wood species, but 30% MC is the commonly-
accepted average.

IS I 2380 ( Part VI ) – 1977
Test procedure
• Initially, Take the specimen with a size of 5cm x 5cm x 2.4cm.
• Then using a weighing machine weigh the specimen. Mark it as W1.
• After that oven-dry the timber at a temperature of 103-degree Celsius.
• Later, take out the specimen when becomes dry.
• Again weigh and mark the weight of the dry specimen as W2.
• Finally, calculate the percentage of moisture content by
• % of moisture content = Weight of moisture in sample/ Dry weight of sample = (W1 – W2)/ W2

Brittleness Properties of Wood
• Brittleness describes the property of a material that fractures when
subjected to stress but has a little tendency to deform before rupture.
• In many cases, due to the tension perpendicular to grain dominating
the failure, wood is perceived to be a brittle material
• Usually the harder a wood, the more brittle it becomes. The hardness
is a reflection of the wood’s density. The tighter packed the fibers,
the less space in between them and less compression.
• A brittle wood breaks suddenly with a clean instead of a splintery
fracture and without warning. Such woods are unfitted to resist shock
or sudden application of load

Testing of Wood Products
• The most common reason for testing wood and timber products is to determine their
ultimate or breaking strength in tension, compression and flexure.
• Most wood products that undergo mechanical testing are used in the construction,
furniture and common goods manufacturing industries.
• The wood and timber products in these industries will experience these forces in various
forms and combinations depending upon their application.
• The measured strength of the wood and timber material will determine if it is an
acceptable candidate for a particular application.

• Moisture Content Test
• Density Test
• Bending Strength Test
• Compression Strength Test:
• Dimensions Stability Test: The dimensional stability is expressed as the sum of the
percentage changes in each dimension between these limits.
Test Method: IS: 4020 (P-3)1998

Wood-based Panels Test:
It is useful for evaluating plywood of clear, straight-grained veneers, and determining the
effect of chemical or preservative treatments, construction, principal direction with respect
to direction of stress, and other variables that are expected to uniformly influence the panel.
Test Method: IS: 4020 (P-1 to 16)1998
Absorbability Test:
This test helps in determining the quantity of water absorbed in a specified time through
the surface of an overlaid wood-based panel.
Test Method: ASTM D 5795.

Screw Holding Ability Test:
The ability to hold screws in both face and edges is an important attribute of wood.
Test Method: IS: 2380 (P-14)1977, RA-2003, IS: 1708 (P-15)1986

Wooden door shutter test
The door shutters shall be subjected to the following tests, in the order listed below:
a) Dimensions and squareness test
• Wooden flush door shutters, when tested, the dimensions of nominal width and height shall be
within a limit of ± 5 mm
• The door shutters shall not deviate by more than 1 mm
• The thickness of the wooden flush door shutters shall be uniform throughout with the
permissible variation of not more than 0.8 mm between any two points.
b) General flatness test
• Wooden flush door shutters, when tested, the twist, cupping and warping shall not exceed 6
mm

c) Local planeness test
• Wooden flush door shutters, when tested, the depth of deviation measured at any point shall
not be more than 0.5 mm.
d) Impact indentation test
• Wooden flush door shutters, when tested, shall have no defects such as cracking, tearing or
delamination and the depth of indentation shall not be more than 0.2 mm
e) Flexure test
• Wooden flush door shutters, when tested, there shall not be any residual deflection of more
than one tenth of the maximum deflection.

f) Edge loading test
• Wooden flush door shutters, when tested, the deflection of the edge at the maximum load shall
not be more than 5 mm. On removal of the loads, the residual deflection shall not be more than
0.5 mm
g) Shock resistance test
• Wooden flush door shutters, when tested, there shall be no visible damage in any part of the
door after twenty five blows on each end.
h) Screw withdrawal resistance test
• Wooden flush door shutters, when tested, the required load to withdraw the screw completely
shall not be less than 1000 N. On withdrawal, there shall be no visible damage to the surface.

Joinery in wood
• Joinery is a part of woodworking that involves joining pieces of wood or lumber, to produce
more complex items.
• Some wood joints employ fasteners, bindings, or adhesives, while others use only wood
elements.
• The characteristics of wooden joints - strength, flexibility, toughness, appearance, etc.

Types of Wood joints
Basic butt joint
mitered butt joint
Biscuit joint
Half-Lap Joint
• Basic butt joint is nothing more than when
one piece of wood butts into another (most
often at a right angle, or square to the other
board)
• Mitered butt joint is nearly the same as a
basic butt joint, except that the two boards
are joined at an angle (instead of square to
one another).
• Biscuit joint is a method of joinery that
involves inserting a compressed wood
chip (the biscuit) in slots cut into two
corresponding pieces of wood.
• Half-Lap Joint where half of each of the
two boards being joined
• Tongue and Groove Joint: One has a
long edge carved at the edge, while the
other has a groove cut in to receive the
board extension
Tongue & groove joint

Types of Wood joints
Dado joint Mortise & tenon joint
Rabbet joint
• Dado Joint: The dado joinery method is
similar to a tongue and groove joint. The
only difference is that the dado is cut
across the woodgrain whereas a groove is
cut in the grain direction which is usually
along the length of the board.
• Mortise and Tenon Joint Mortise and
Tenon joinery continues to be one of the
strongest wood joints to use for framing
and building.
• Rabbet Joint is a method of joinery that
form a recess into the edge of the timber.
Dovetail Joint: It uses interlock joinery of
a series of pins and tails to create a resili
Dovetail joint

Testing of wooden joints
• Joints are generally the weakest part of furniture
and they are primary cause of failure. To ensure
durability and performance of furniture, it is
important for a designer to understand the stresses
acting on the joints for preparing suitable design
and specification of a furniture.
• Since each type of joint is unique in construction,
it is important to know their strength, when
subjected to various stresses namely shear,
bending, and tensile, by testing the joints.

Wood packaging case
• Wooden packaging is always designed according
to the specific product to be packed, transport and
storage conditions, destination, legislative
standards etc.
• Wooden packaging can be supplied unfolded,
folded, or the specific product you can be packed
directly (often in combination with other
packaging materials) and prepared for transport.

Treatment of Wood packaging case
Wood Heat Treatment (HT):
• Treatment can eliminate harmful insects
and nematodes in wood materials. All
treated WPM will have the IPPC mark, as
shown below:
XX – indicates a two letter ISO country code
YY – This indicates the type of treatment, and
will either be HT (Heat Treatment) or MB
(Methyl Bromide).

Treatment of Wood packaging case
Waterproof Treatment
To avoid dampening the equipment due to
long-distance transportation, the following
types are generally used.
• Cover with canvas
• Place desiccant in wooden packing crates
• Wooden Vacuum Packing

Wooden handle
• When selecting timbers for tool handles, strength,
shock resistance and ability to absorb vibration are
the essential qualities.
• Smooth working and non-splitting characteristics
are also required.
• Non-splitting characteristics are needed, timbers
with interlocked grain are mostly used.
• The timbers used for handles should be properly
air or kiln dried.

Performance and property requirements of wooden handles
• Generally, it is important that handles for impact
tools such as axe and hammer possess good
strength properties. To withstand impact shock,
high density and the right direction of grain are
required. On the other hand, tool handles for
nonimpact purposes, such as for rake, shovel,
spade, garden fork and some other small hand
tools, require properties which are less stringent
and timbers of lower quality can be used

Agriculture implements of wood
• Agricultural implements are tools which are
required to carry out agricultural practices. There
are a number of agricultural implements used in
today’s farming activities. In general, these
implements are of five major types.
• Wooden implements are as follow;
 Wooden plough

 Leveler

Mallot:
Khilna
Spade
sikle (Daranti)

Wooden sports goods
• Sports goods are those objects which are used in
sports.
• Wood plays an important role in some of our
favorite recreational activities or athletic pastimes.
• Nearly every sport uses or has used some sort of
wooden implement.

Species used for manufacturing wooden sports goods

Factor of safety (FoS) :
• Suppose this bridge can support maximum 18 people at a time
• The weight of those 18 people is the ultimate stress.
• But, bridge construction company doesn't allow 18 person at
a time
• If the company allow only 6 people at a time.
• Then, the weight of those 6 people is working stress.
• On the above scenario, factor of safety = 18/6 = 3

Unit-14
Factor of safety (FoS) :
• The ratio of the ultimate strength of a member or
piece of material to the actual working stress or
the maximum permissible stress when in use
• factor of sfety is ability of a system's structural
capacity to be viable beyond its expected or actual
loads.
• An FoS may be expressed as a ratio that compares
absolute strength to actual applied load, or it may
be expressed as a constant value that a structure
must meet or exceed according to law,
specification, contract or standard

Unit-14
Ultimate stress:
• Ultimate stress refers to the maximum stress that a
given material can withstand under an applied
force.
• The ultimate tensile strength formula is:
S = F / A
where
S = the breaking strength (stress)
F = the force that caused the failure
A = the least cross sectional area of the
material

Unit-14
Working stress:
• The stress to which material may be safely
subjected in the course of ordinary use
• Working stress is the safe stress taken within the
elastic range of the material.

Unit-14
Yield strength:
• Also called elastic point
• Yield strength refers to an indication of maximum
stress that can be developed in a material without
causing plastic deformation.

Importance of Factor of Safety
• A factor of safety increases the safety of people and reduces the risk of failure of a product.
• When it comes to safety equipment and fall protection, the factor of safety is extremely
important.
• If a structure fails there is a risk of injury and death as well as a company’s financial loss.
The safety factor is higher when there is a possibility that a failure will result in these things.
• Maintains the structure’s functionality for the future while providing additional safety for
current use
• Prevents damage to property, workers, and machines
• Provides protection for unforeseeable risks that may occur while using a product or service
• Reduces the chances that a product may fail

Factor of Safety depend on
• Actors to be considered while selecting the factor of safety:
• The properties of the material and the possible change of these properties
during operation.
• Type of applied load, whether it is Gradual or Impact.
• Initial stresses set up during manufacturing of component.
• The extent of localized stresses.
• Mode of failure

Use of tree species
• Trees and wood have been an integral part of the development of our
civilization.
• Different types of wood have been used from early Paleolithic times for
constructing buildings, woodworking, manufacturing tools, construction
equipment, weapons, and furniture.
• Right from ancient times, the use of wood has been dependent on cost,
quality, and availability.

End use of tree species
• All these mentioned species are famous for their
use in various commercial activities like: Timber
for building construction purposes,
• furniture, cabinet making, ceiling flooring,
Railway sleepers etc. and are used as sources of
raw material for various forest based industries.
Pencil Making Railway Sleepers Plywood
Industry
• Cedrus deodara and Tectona grandis are two of
most durable timber. • Resin is extracted from
Pinus roxburghii and Shorea robusta, they also
yield Timber. • Heartwood of Acacia catechu is

End use of tree species
• Shorea robusta, Delbergia sissoo, Cedrus
deodara and Tectona grandis are two of most
durable timber.
• Resin is extracted from Pinus roxburghii
• Heartwood of Acacia catechu is main source of
raw material for Katha and Cutch industry
• Casuarina equisetifoia, Anogeissus latifolia are
used in Charcoal industry.

Growth of tree Species
Growth Nepali name Scientific n.
Fast
growing
species
l;l/; Albizzia spp.
plQ; Alnus nepalensis
sbd Anthocephalus
cadamba
l;dn Bombax ceiba
lz;f} Dalbergia sissoo
d;nf Eucalyptus spp.
asfOgf] Melia azedarach
rfFk Michelia champaka
lsDa' Morus alba
kf6] ;Nnf,
cd]l/sg ;Nnf
Pinus patula
nx/] lkkn Populus deltoids
l6s Tectona grandis
t'gf Toona ciliata
udf/L Gmelina arborea
Growth Nepali name Scienti n.
Medium
growing
species
vo/ Acacia catechu
s6'; Castanopsis spp.
df}jf Englehartia spicata
vf]6] ;Nnf Pinus roxburghii
uf]a|] ;Nnf Pinus wallichiana
lrnfpg] Schima wallichii
;fh Terminalia tomentosa
Slow growing
species
km/ Abies pindrow
b]abf/ Cedrus deodara
laho ;fn Pterocarpus
marsupium
v;|' Quercus spp.
;fn Shorea robusta
nf}7;Nnf Taxus baccata
l7+u|] ;Nnf Tsuga dumosa

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