Influence of thermal residual stresses on the free vibration of reinforced laminates

Abstract

The use of laminated composite materials has increased in modern engineering, mainly in those projects that require an assurance of good strength and durability. It has been found that some properties of the material that ensure proper performance can be affected by the occurrence of residual stresses caused by the manufacturing process. In this paper, the influence of thermal residual stresses on the free vibration of reinforced plates is analyzed. For the experimental study, a square, reinforced, prepreg laminate was used. The laminate was reinforced using two different types of reinforcement: lateral and perimetral. The plates were prepared using two different techniques. The first group of laminates was prepared by curing the reinforcement at 177 °C. The second group of laminates was prepared by secondary bonding of the reinforcement to the laminate at room temperature (22 °C). A numerical model was elaborated for comparison with the experimental results. Accuracy was observed when comparing experimental and numerical results, showing that the presence of residual thermal stress affects the value of the natural frequencies of free vibration and the characteristic modal form of reinforced plates. Regardless of the type of reinforcement used, a notable increase in these values was observed, even when the element was simply supported.

Keywords

• Laminates
• thermal stresses
• free vibration
• frequency
• cure temperature