A literature review on CTE and DMA of composite material

1. Hex ply AS4/8552 composite (data taken from sheets)
-0.63x10-6

2. Moisture and Thermal Expansion Properties of
Unidirectional Composite Materials and the Epoxy
Matrix

3. Prediction of Thermal and Mechanical Properties
of Glass-Epoxy Composite Laminates

4. Prediction of Thermal and Mechanical Properties
of Glass-Epoxy Composite Laminates

5. Usually the cte of matrix is positive and
larger than fiber cte
When vf is less then 0.15,cte is dominated by
matrix
When vf is greater than and equal to 0.5,cte
is dominated by thermal property of fiber

7. Thermal expansion behaviour depends on
thermomechanical properties of its internal
components

8. In literature people plotted thermal strains
with temperature
Temperature-dependent thermal expansion behavior of carbon fiber/ epoxy plain woven composites:

9. Aluminum and Aluminum Alloys. The dimensional change of aluminum and its alloys with a change of temperature is
roughly twice that of the ferrous metals. The average CTE for commercially pure metal is 24 × 10–6/K (13 ×
10–6/°F). Aluminum alloys are affected by the presence of silicon and copper, which reduce expansion, and
magnesium, which increases it. Its high expansion should be considered when aluminum is used with other materials,
especially in rigid structures, although the stresses developed are moderated by the low elastic modulus of aluminum.
If dimensions are very large, as for example in a light alloy superstructure on a steel ship or where large pieces of
aluminum are set on a steel framework or in masonry, then slip joints, plastic caulking, and other stress-relieving
devices are usually needed. In the aluminum internal-combustion engine piston that works in an iron or steel cylinder,
differential expansion is countered by the employment of low-expansion iron cylinder linings, or by split piston skirts
and nonexpanding struts cast into the piston.
Chapter 2 Thermal Expansion

10. The CTE of all samples was reduced by the addition of graphite. Graphite
has a CTE of –1 ppm K–1 in-plane and 28 ppm K–1 through-plane [27].
Remarkably, the CTE of the sintered samples fell down to low or even
negative values through-plane, while the in-plane reduction did not
exceed 30% in comparison to the metal matrix.
Firkowska et al. [12] observed a similar effect in copper–graphite
composites with equivalent microstructure and attributed it to an in-plane
stretch of the graphite crystal caused by the expansion of the metal
matrix. Under consideration of the temperature dependence of the elastic
constants and the effects of the cooling after sintering, the model predicts
a shrink in the graphite crystal in the through-plane direction. This
compensates the overall expansion of the sample along this axis. In our
composites the higher CTE of the matrix led to higher in-plane CTE and
showed, as expected from the model, a lower through-plane CTE than
copper–matrix composites. Many metal matrices used here have too
Composites of aluminum alloy and magnesium alloy with
graphite showing low thermal expansion and high specific
thermal conductivity

12. Coefficients of thermal expansion for different substrates and
adhesives are presented in Table 17.1. The CTEs can be
determined by dilatometry, by strain gauges (da Silva and
Adams, 2008) or by a bi-material curved beam method (Yu et
al., 2003; Loh et al., 2005). Let us look at the residual stresses in
a joint with aluminium and a CFRP for example. With a negative
thermal load, that is with a decrease in temperature from the
stress-free temperature (TSF), and a compliant adhesive, the
aluminium and the composite adherends can contract freely
(see Fig. 17.1a). Note that, in fact, the length of the composite
adherend does not
change because its longitudinal CTE is close to zero. However,
for a stiff adhesive in its glassy region, the adherends cannot
contract freely so that the composite is subjected to a
compressive axial load and the aluminium adherend is under
tension (see Fig. 17.1b). However, the axial load causes bending
of the joint as indicated in Fig. 17.1(c). The resultant stress will
then be the sum of the uniform component caused by the axial
load plus the linearly varying (through the thickness)
contribution caused by bending. Whether the bending
component is higher than the uniform direct component
depends on the geometry and the material properties.

13. However, more important than the thermal stresses in the
adherends are the stresses in the adhesive. For
metal/composite joints for example, the metal tends to shrink
as the temperature is decreased from the cure value (generally
a high temperature) and this is partially resisted by the
composite (lower CTE), thereby inducing residual bond stresses
especially at the ends of the joint. One end has positive
residual shear stresses and the other end has negative residual
shear stresses (see Fig. 17.2). The thermal stresses are
beneficial at one end of the joint but have the reverse effect on
the other side of the joint. The thermal load DT is given by
Equation 17.1:

14. Behavior of Al-Mg Alloy Subjected To Thermal Processing

15. Effect of Temperature on Material Properties of Carbon Fiber
Reinforced Polymer (CFRP) Tendons: Experiments and Model
Assessment

16. According to the ACI 440.1R [23], the coefficient of thermal
expansion (CTE) of CFRP tendons is between −9.0 × 10−6/ ◦C
and 0.0 × 10−6/ ◦C in the longitudinal direction. However, the
variation of CTE with temperatures is not clear. The
experimental results show that the longitudinal deformation of
CFRP tendons decreased with the increase of temperature
(Figure 5), which verifies the fact that the FRP composites
shortened along the fiber direction at elevated temperatures
[24]. This is mainly attributed to fact that carbon fibers shrink
at elevated temperatures in the longitudinal direction [25].
With the increase of temperature, the shrinkage of carbon
fibers dominated the longitudinal deformation of CFRP tendons
due to the softening of the resin. When the temperature was
low, the CTE decreased slowly. As the temperature rose, the
resin of FRP composites began to soften, and the CTE of CFRP
tendons decreased to a larger negative value. Especially, when
the temperature exceeded 200 ◦C, the CTE decreased rapi

17. α = −1.5 × 10−6
(T − 23)
3 + 3.17 × 10−4
(T − 23)
2 − 2.44 × 10−2
(T − 23) + 0.015
creased to a larger negative value. Especially, when the
temperature exceeded 200 °C, the CTE decreased rapidly.
Finally, the longitudinal deformation of CFRP tendons was
unstable after 300 °C due to the decomposition of the resin,
resulting in the failure of obtaining its thermal expansion
properties. Based on the experimental data, the longitudinal
CTE (10−6/°C) of CFRP tendons is proposed in the form of
polynomial function (Equat
Effect of Temperature on Material Properties of Carbon Fiber
Reinforced Polymer (CFRP) Tendons: Experiments and Model
Assessment

18. Evaluation of thermal expansion coefficient of carbon fiber
reinforced composites using electronic speckle
interferometry

20. Testing of adherents
• Properties of carbon fiber
• Thermo-mechanical properties of carbon fiber
• Tensile strength testing of composite
• Fatigue strength of composite
• Three point bending
• Four point bending
• DMA
• Fiber volume fraction of composite
• DSc of composite
• Tensile strength testing of metal alloy
• Three point bending
• Tensile strength of resin araldite 564 and araldite 2011
Discuss with dr. khubab too

21. Properties of materials from literature
Type of material Aluminum alloy Carbon fiber Glass fiber Ly 564/22962
matrix
Araldite 2011
Adhesive
Type Al 7075-T6 AS4 12 K (12000
filaments)
E glass Ly 564 araldite 2011
GSm
Glass Transition
Temperature (Tg)
138 oc when cure
at 80 oc for at 1
hour + 150 oc for2
hours
Ultimate Tensile strength o f
material
510-540 MPa 4413 MPa 75-80 MPa (15
min at 120 + 2 hr
at 150 oc)
Tensile strength of
composite in 0 direction
2205 MPa
Flexural strength in 0 1889 MPa

22. Properties of materials from literature continued
Type of material Aluminum alloy Carbon fiber Glass fiber Ly 564 matrix Araldite 2011
Adhesive
Soilidus 470 oC
Liquidus 635oC
Typilcal cure

23. Points of discussion on adhesive post curing
1. Difference in post curing under compression molding and oven
2. Post curing temperature will be different of binder and composite

24. New plan for dma and tma

25. Compression mode in TMA
• To Check Viscoelastic behabiur of lap joints
• Temperature ramp 25 to 200
• Temperature

26. Compression mode on TMA
Number of
samples
Force (maximum
applied force)
Temperature
(ramp)
Surface treatment Output (creep)
1 Maximum force 25-150 1 (comp)
2 Maximum force 25-150 2 (comp)
3 Maximum force 25-150 3 (comp)
4 Maximum force 25-150 4 (metal)
5 Maximum force 25-150 5 (metal)
6 80% of maximum
force
25-150 1 (comp)
7 80% of maximum
force
25-150 2 (comp)
8 80% of maximum
force
25-150 3 (comp)