Research On The Methods For Reliability Analysis Of Mechanical Joint In Laminated Composites

Mechanical joints have been applied more and more widely in composite structures. However,because of the large stress concentration around the bolt hole, mechanical joints are a critical issue ofcomposite structural component. Due to the complicacy of composite manufacturing processes, themechanical properties of composite materials always display obvious scatter, and there also existsmany other uncertainties. Thus, an appropriate method for estimating the probabilistic strength of themechanical joint in laminated composites is important for reliability based design of compositestructures.Based on a combination of subset simulation method and two-dimensional finite element model,a new method is established for predicting the probabilistic strength of the composite joint whenuncertainties in material properties are modeled as random variables. By utilizing the presentedmethod, the effects of the failure criteria, the associated degradation and non-linear shear behavior onthe probabilistic strength of composite joint are investigated.Then, in order to solve the deficiency of subset simulation method, which requires a massivefinite element simulation calculation, a probabilistic strength analysis method based on responsesurface method is presented, and the verification on this method has been implemented on the base oftwo-dimensional finite element model. To proceed a further investigates on the robustness andaccuracy of the proposed method, a parameterized three-dimensional finite element model has beenbuilt, and the influences of different progressive damage criteria and interpolation coefficient havealso been considered.Finally, static strength and probabilistic strength of the three forms of composites mechanicaljoints have been calculated respectively by three-dimensional finite element model and responsesurface method. The influences of the scatter of basic random variables on the probabilistic strength ofdifferent composites joints are also investigated.