PROBABILISTIC STRENGTH ANALYSIS OF 4-DIRECTIONAL LAMINATED COMPOSITES

An analytical probabilistic model of multi-step failure of a laminated composite is presented for four-directional reinforcement schemes. Fr om the viewpoint of failure process analysis, the schemes ave consider ed as fiber-dominated structures. Fiber strength therefore plays a cru cial role and the structure is able to resist a loading, even if a com posite has been, discontinued. Relationships for reliability prognosti cation, accounting for random nature of lamina strength properties as well as stress state, are offered and experimentally confirmed for mul ti-laminated four-directional composites. On the basis of the concept of sublaminates, it is shown that the reliability evaluation may be ca rried out in the form of two independently solved problems: probabilis tic failure analysis of a sublaminate and a sublaminate bundle. Reliab ility of the sublaminate with a structure [0/+/-Theta/90] is considere d in detail and respective numerical results ave presented. Experiment al confirmation of the theoretical results is considered for an exampl e of uniaxial tension of a carbon-fiber-reinforced composite with a [0 /+/-/45/90](4) structure. (C) 1996 Elsevier Science Limited