GATE 2019 MT – Question 59
A composite has alternating layers of metals A and B, with 25 vol% B. Their elastic moduli are 200 and 100 GPa. Loading is perpendicular to the layers as shown. Find effective modulus in GPa (one decimal place).
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Correct answer: 155.0 to 165.0
Explanation
Loading normal to layers gives equal stress, while total strain is the volume-weighted average. Thus $1/E_c=V_A/E_A+V_B/E_B=0.75/200+0.25/100=0.00625$ GPa⁻¹. Therefore Ec=160.0 GPa. The arithmetic rule would apply for loading parallel to layers.