P4.5. Tensile stress-strain diagram of a [0/9041s AS-4 carbon fiber-epoxy lamina
ID: 1767292 • Letter: P
Question
P4.5. Tensile stress-strain diagram of a [0/9041s AS-4 carbon fiber-epoxy laminate is shown in the figure. The longitudinal modulus and trans- verse modulus of a 0 unidirectional laminate of the same material are 142 and 10.3 GPa, respectively. 1. Determine the initial axial modulus of the [0/9041s laminate and compare it with the theoretical value. How would this value change if the 90° layers are at the outside or the laminate construction is changed to [02/903ls? 2. The knee in the stress-strain diagram is at a strain of 0.005 mm/mm. However, the ultimate longitudinal and transverse strains of the 0 unidirectional laminate are at 0.0146 and 0.006 mm/mm, respect- ively. Explain what might have caused a lower strain at the knee 3. Describe the reason for the nonlinear portion of the stress-strain diagram 300 100 0.3 0.9 Strain (percent) 0 0.6 1.2 1.5Explanation / Answer
1. Initial axial modulus is always 0.2%of elastic modulus
2. The presence of dislocation made the strain rate low
3. Non linear portion is because of presence of dislocation and low dislocation density.
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