复合材料层板损伤力学的实验研究——损伤应变能释放率破坏判据

 一、前言 鉴于复合材料层板的结构特点和独特的破坏机理,作者曾经讨论过最近发展起来的固体力学新分支——连续介质损伤力学在复合材料层板中的应用,并指出了损伤力学可能是研究含缺陷复合材料强度的更有效的工具。 从70年代到现在,各向同性损伤理论已经得到了仔细的研究,并在大变形塑性损伤,蠕变损伤和疲劳损伤等方面的应用中取得了初步成功。

EXPERIMENTAL STUDY ON DAMAGE MECHANICS OF COMPOSITE LAMINATES--DAMAGE STRAIN ENERGY RELEASE RATE FAILURE CRITERION

So far the failure criterion of damaged composite laminates is consistently one of the important research projects for the investigations of me- chanics of composite materials. Because of the complexity of damage failure mechanisms of composite laminates, the failure criterion applied to all forms of defects, particularly impact damage has still not been found. In the present paper authors attempt to apply continuum damage mechanics to solving this puzzle.Based on the energy identification hypothesis authors propose that the damage strain energy release rate tensor can be used to describe the mechanical state of damaged composite laminates. And the experimental study of two notched carbon/epoxy laminates （（0/±15） and （0/±75）） shows that the evolution law of the damage strain energy release rate can be fitted in with an exponential function. Therefore, the damage strain energy release rate failure criterion applicable to composite laminates under unidirectional loading is obtained.By means of some destructive and nondestructive inspections, such as the acoustic emission, out-of-plane morie inteferometry, load-displacement curve and deply technique, the experimental study on damage failure mechanisms were carried out to verify and reveal the physical meaning of this criterion and the reasonableness of some assumptions in this criterion theory.