1. UNIVERSITÀ DEGLI STUDI DI SALERNO
FACOLTÀ DI INGEGNERIA
CORSO DI LAUREA MAGISTRALE IN INGEGNERIA MECCANICA
TESI DI LAUREA MAGISTRALE
“Functional simulation of a pneumatic breaker by using Hopsan NG
software”
RELATORI:
CH.MO PROF. IVAN ARSIE
CH.MO PROF. ADOLFO SENATORE
CORRELATORI:
CH.MO LISELOTT ERICSSON, Linkoping Universitet
ING. THOMAS LILJA, Atlas Copco
CANDIDATO:
NICOLA MELONE
MATR. 0622300467

2. Summary
• Atlas Copco – Brief presentation
• Master thesis: Aim – Method – Limitations
• Hopsan NG
Pneumatic library
• Hopsan NG – Breaker Modelling
Fixed-striking-point Model
Floating-striking-point Model
• Dynaload test – Test procedure – Material modelling
Standard test
Lab equipment
Rock modelling in Hopsan
• Results
Validation & Fine-tuning of the model
Vibration analysis
Feed force analysis

3. Industrial Technique Service
MVI Tools and Assembly
Systems
General Industry Tools
and Assembly Systems
Chicago Pneumatic Tools
Compressor Technique Service
Industrial Air
Oil-free Air
Gas and Process
Quality Air
Specialty Rental
Airtec
Mining and Rock Excavation
Service
Underground Rock
Excavation
Surface Drilling
Drilling Solutions
Exploration and Geotechnical Drilling
Rock Drilling Tools
Rocktec
Construction
Technique Service
Portable Energy
Road Construction Equipment
Construction Tools
Industrial
Technique
Group Management and corporate functions
Compressor
Technique
Mining and Rock Excavation
Technique
Common service providers
President and CEO
Board of Directors
Construction
Technique
3
Kalmar
Örebro
Linköping
Support from their
knowledge in Hopsan –
hydraulic systems
( Maria Petterson )
Support from the
University: Hopsan –
developers
( Peter Nordin )
I am here!

4. Machine
Software used during the design
Dymola model - Features
 Simulation of the percussive mechanism
 No - Feed force analysis
 No - Vibration analysis
 No – Modelling of the material to crush
Software to test
Dassault SystèmesDeveloped at the division of Fluid and
Mechatronic systems at Linköping University
Rtex 25
 Simulation of the percussive mechanism
 ( Hydraulic applications )
 Feed force analysis
 Vibration analysis
 Modelling of the material to crush

5. Step 1: Modelling the percussive
mechanism - Hopsan
Step 2: Modelling the complete
system and the Material
- Hopsan
Step 3:
Vibration analysis
Feed force analysis
Check: Performance Comparison -
Model in Dymola and Real Machine
Check: Performance comparison –
Percussive system in Hopsan, Model
in Dymola and Real Machine

6. A Component which simulates properly a
channel filled by compressible fluid is missing Leads to
Several solutions to
overcome this problem
ChannelPInlet
Scheme to look at:
PInlet >POutlet
POutlet
1D modelling approach
A 3D problem cannot be simulated

7. Q-type components:
1. read characteristics
2. calculate flow and pressures
C-type components:
1. read flow and pressure (Q and P)
2. calculate characteristics (solve the wave
equation)
A pneumatic line is
missing!
It is substituted by a
”lumped” pneumatic
volume

8. 1. Inlet
2. Upper cylinder chamber
3. Piston
4. Lower cylinder chamber
5. Valve => connects the
inlet to the lower
chamber during the
return stroke
1
2
3
4
5
• During the working stroke the upper
chamber is pressurised and the lower
chamber is at the atmospheric pressure

9. Stiffmachine
- The housing is ”fixed”
- No vibrations
Oscillatingbehaviour – Real application
- The housing is oscillating
- Vibrations
Modelling of the percussive
mechanism
Modelling of the whole system with the proper
operator feed force and the real material

10. Legend:
- Red: high pressure line
- Blue: low pressure line
- Black: mechanical link
•Since the striking
point is fixed, it
has been used as
reference
To set the rebound velocity for
the piston after each strike

11. Legend:
- Red: high pressure line
- Blue: low pressure line
- Black: mechanical link
•Since each blow takes place in
different position, the top of the
breaker is assumed the
reference system
Sensor to
measure the
stress waves
Anvil block
Chisel
Material

12. Standard test to measure the breaker’s
permformances such as
1. Noise
2. Vibration
3. Frequency
4. Energy
 Power=Energy*Frequency
Device
Diameter depends on the
hand-held power tool
• 20 mm
• 40 mm
• 60 mm
Reflect the 15-
20% of the shock
wave

13. Measurements set-up
Dynaload test - equipment
• Vibration test:
• Feed force 24 kgf applied
by an operator
REFERENCE: SS-EN_ISO_28927-10_2011
Key:
• 1 = steel balls energy
absorber
o The operator is
standing on a scale
• Energy test:
• Maximum Feed force 56
kgf applied by 2 straps
Strain gauge
Chisel

14. Rock behaviour = ”spring”
Example: Wave as an impulse
Main parameters:
1. K1= loading stiffness
2. K2=elastic unloading stiffness
• (A) = the force ( wave ) is travelling in the
chisel
• (B) = the force built in the spring has a
”deformed” shape
• (C) =the force is capable to crush the
material effectively=>penetration=>free
end=>reflection opposite sign
• (D) = after a while the rock becomes stiff
=>no penetration=> closed
end=>reflection same sign
Free end
Closed end

15. Real stress waves
VS
4 Different Simulated rock
models
Simulation
• Impact energy 74 J
Measurement on one-year-
working Rtex 25
• Impact energy 68 J Our choice?
The green line!

16. Pressure profile
Lower chamberUpper chamber
Always pressurised
in the whole cycle
at 600 kPa
Pilot channel-
Used to open (600
kPa) or close the
valve & it connects
the upper chamber
to one port of the
valve
Less wide
because of the
higher operating
frequency

17. Performance
Relative pressure - 6 bar
HOPSAN-Complete model-max feeding
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
143 13,3 74 984 19,8
REAL MACHINE – max feeding
Stroke[mm] Freq[Hz] E[J] P[W] Air[l/s]
not measured 13 74 962 18,5
DYMOLA – percussive mechanism
Stroke[mm] Freq[Hz] E[J] P[W] Air[l/s]
134 14,5 64 928 17,4
HOPSAN-percussive mechanism
Stroke[mm] Freq[Hz] E[J] P[W] Air[l/s]
146 13,1 74 964 19
It is needed to get
less vibrations!

18. Rtex 25 : Performance at different working pressure
HOPSAN-COMPLETE MODEL
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
132 14,8 86 1273 26,1
REAL MACHINE
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
not measured 14,2 80 1136 not measured
Relative pressure = 7 bar Relative pressure = 8 bar
REAL MACHINE
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
not
measured
14,4 87 1253
not
measured
DYMOLA-percussive mechanism
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
138 16,2 91 1474 25
DYMOLA-percussive mechanism
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
143,5 15 83 1245 21,3
HOPSAN-percussive mechanism
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
140 14 83 1162 23
HOPSAN-percussive mechanism
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
132 14,7 84 1235 25,7
HOPSAN-COMPLETE MODEL
Stroke [mm] Freq[Hz] E[J] P[W] Air[l/s]
142 14,1 83 1170 23,5

19. Whole-body vibration Hand-arm vibration
Human vibration is defined as the effect of
mechanical vibration on the human body.
Exposure to whole-body vibration can either
cause permanent
physical damage, or disturb the nervous
system.
REFERENCE: Human vibrations - Brüel & Kjaer - booklet
Daily exposure to hand-arm vibration over a
number of
years can cause permanent physical damage
usually resulting
in what is commonly known as "white-
finger syndrome“.
Hand-held
machines
•The main parameter used
to calculate the vibration
level is the RMS value ( or
equivalent acceleration )

20. Frequency band number Nominal centre frequency Weighting factor
6 4 0,375
7 5 0,545
8 6,3 0,727
9 8 0,873
10 10 0,951
11 12,5 0,958
12 16 0,896
13 20 0,782
14 25 0,647
15 31,5 0,519
16 40 0,411
17 50 0,324
18 63 0,256
19 80 0,202
20 100 0,16
30 1000 0,0135
Standard procedure to obtain the result:
• Perform the 1/3-octave band analysis within the range
of 6 Hz and 1250 Hz;
Hand-arm vibration
• Apply the STANDARD ISO 8041 weighting filter for the
hand-arm vibrations

21. Average over 3 measurements
After the weighting filter
56 kgf by straps Operator 24 kgf
RMS[m/s2] 15,3 3,2
Simulation - HOPSAN
After the weighting filter
56 kgf by traps Operator 24 kgf
RMS[m/s2] 16 2,19
Vibration level along the working direction
One order of magnitude!!
WHY?
Test 1 with the operator
Real signal
56 kgf by Straps Operator 24 kgf
RMS[m/s2] 38 5,12
Real signal
56 kgf by straps Operator 24 kgf
RMS[m/s2] 109,7 34,6
One plausible exaplanation:
Chisel mass = 23 kg
Piston mass = 1,7 kg
Anvil mass = 0,2 kg
•Since the anvil has a really small weight
it may oscillate like a ”maracas”, while in
the simulation the behaviour is more
controlled. Its dynamic is not well
reproduced.
Anvil
Hand-arm vibration
Results coming from HOPSAN

22. z
Real machine
Hopsan
LEGEND
•Acceleration along z
•Stress magnitude

23. Minimum
Feed[kg]
RMS [m/s2] – z-axis
17 4,97
Minimum
Feed[kg]
RMS [m/s2] - z-axis
26 2,19
Simulation - With leakage
from lower chamber to
anvil
Simulation- Without
leakage
Real machine
RMS [m/s2]
x 2,30
y 1,08
z 3,18
vector_sum 4,07
y
z
Trade-off between
acceleration level
and feed force
Machines with this
size have a limit on
the vibration level
of 5 m/s2
Real machine
RMS [m/s2]
z 6,5
vector_sum 8
Real machine- With
leakage from lower
chamber to anvil
Real machine- Without
leakage
In-depth analysis
Leakage

24. Hopsan - Relative operating pressure = 6 bar – Average value in 3 seconds of simulation
Stroke
[mm]
Freq[Hz] Vel[m/s] E[J] P[W] Air[l/s] Striking point [mm] (α)
Force
[kg]
Efficiency
[-]
min aver max
146 13,26 9,55 75,2 997,7 19,8 7,00E-05 6,00E-02 3,00E-01 40 0,69
152 13,09 9,67 77,1 1009,8 20,0 0,9 1 1,14 35 0,68
157 12,88 9,8 79,2 1020,5 20,0 0,5 4 9 30 0,68
185 11,8 9,8 79,2 934,9 19,0 22 25 27 26 0,57
Legend:
• Increase
• Decrease
!
Wider striking point gives
higher pressure in the lower
chamber which dissipates
energy, because it breakes
the piston!
α
Efficiency
Striking energy/Available Energy

25. α
High feed force
WHY?
Float[mm] (α)
Force
[kg]
min aver max
7,00E-05 6,00E-02 3,00E-01 40
0,9 1 1,14 35
0,5 4 9 30
22 25 27 26
Because high feed force makes the housing get in
contact with the anvil before each strike occurs
Is it positive?
It gives higher efficiency
It also gives high vibrations
Average over 3 measurements
56 kg by straps Operator 24 kg
RMS[m/s2] 15,3 3,2
The feed force must
be on a proper level !
The striking point has less variation
Efficiency[-]
0,69
0,68
0,68
0,57

26. Model built in DymolaModel built in Hopsan
 Simulation of the percussive mechanism ( Hydraulic, Pneumatic )
 Feeding force analysis
 Materials modelling
 Vibration analysis
Can be improved performing measurements on other
materials
The situation is too ideal about the high frequencies as the
behaviour of the anvil is not well reproduced
In Hopsan only the 1D modelling is possible, thus
we don´t have vibrations in other directions
We started from
We ended up to
 Simulation of the percussive mechanism
 No - Feed force analysis
 No - Vibration analysis
 No – Modelling of the material to crush
 Simulation of the percussive mechanism
 ( Hydraulic applications )
 Feed force analysis
 Vibration analysis
 Modelling of the material to crush

27. • ”Intuitive” program
• ”Hard” is to model the components ( I´ve had the library ready )
• Matlab-Hopsan-Excel => different format supported & can communicate with other software
• We´ve started to implement some optimization as well once the models were ready
• Skilled persons can build an own library and simulate whatever they want ( as Atlas Copco is doing )
• It´s FREE!

28. Thank you for the attention!