Research On Impact Damage And Damage Tolerance Of Composites Laminates

Composites materials are widely used in aerospace structures because of the high specificstrength and stiffness, design-versatility, anti-corrosion and other excellent features; but the impactresistance of composite structures is poor; it can cause a variety of forms of damage when thestructure suffers impact during manufacture and work-and once it happened, the bearing capacitywill be reduced heavily. When it is subjected to low velocity impact, delamination damage may alsooccur even without obvious damage on the surface, and the bearing capacity will be affected seriously.Therefore, it has profound engineering significance to study the low velocity impact damage anddamage tolerance of composite laminates.Based on a three dimensional analysis theory of cumulative damage, using a commercial finiteelement software and developing the user subroutine, the process of low velocity impact to laminateswas simulated. At the same time, the experiment of low velocity impact was carried out. Theconsistency of the test results and the numerical results in this paper demonstrated the feasibility ofthe numerical simulation method. Based on the experiment and numerical simulation, this paperstudied the effect of the impact energy to laminates in low velocity impact; analyzed thecharacteristics and mechanism of low velocity impact damage in different time in detail, and revealedthe reasons and spreading laws of fiber damage, matrix damage and layering.In order to study the damage tolerance properties of composite laminates, the residualcompressive strength of laminated plates after impacting are studied. This paper explores theinfluence of different factors on residual compressive strength including the stacking sequence, angle,and successive ply. It provides some guidance for the design of composite structures.