Abstract

Due to the high strength to weight ratio of composites, their applications are extending rapidly in many industries. Composites can be fabricated by using different constituent (including fiber and matrix) materials. Different curing cycles and thermal expansion coefficients of matrix and fibers in hybrid composites may lead to residual stresses and distortion. Residual stresses can decrease the durability of the part during commissioning, and distortion makes the assembly process more difficult or even impossible. In this study, different inter-ply hybrid laminates reinforced by carbon and glass fibers are fabricated by hand lay-up method. After curing, they are cooled by three different rates. Distortions of laminates are measured by coordinate measurement machine and their residual strains are measured by the incremental hole drilling method. Calibration factors are calculated by simulation and finally, residual stresses are determined. Also, residual stresses and distortion of laminates are predicted by classical lamination theory and finite element method. The obtained results are compared and acceptable conformity is seen. Comparison of experimental distortion results showed that cooling rates in the laminate which have more degree of un-symmetry will lead to 100 percent deviation of numbers.

摘要

由于复合材料的高强度重量比，它们的应用在许多行业中迅速扩展。复合材料可以通过使用不同的成分（包括纤维和基体）材料来制造。混合复合材料中基体和纤维的不同固化周期和热膨胀系数可能导致残余应力和变形。残余应力会在调试过程中降低零件的耐用性，而变形会使装配过程更加困难甚至不可能。在这项研究中，不同的由碳纤维和玻璃纤维增​​强的层间混合层压板是通过手糊法制造的。固化后，它们以三种不同的速度冷却。层压板的变形通过坐标测量机测量，其残余应变通过增量钻孔法测量。通过模拟计算校准因子，最后确定残余应力。此外，通过经典层压理论和有限元方法预测层压板的残余应力和变形。比较获得的结果并看到可接受的一致性。实验变形结果的比较表明，具有更多不对称度的层压板中的冷却速率将导致100％的数字偏差。