Global-local finite element stress analysis of thick laminate multi-bolt joints in large-scale structures

Accurately accessing the three-dimensional stress distribution through the thickness surrounding the bolt hole is necessary to identify the most effective multi-bolt single-lap joint design in large-scale thick laminate structures. To decrease computing time and resources, a two-dimensional to three-dimensional global-local finite element numerical method is presented, in which both the local zone selection strategy and boundary constraints applying method are discussed in detail. And both the contact stress and the stress components around the fastener hole are analyzed by using the proposed global-local method. Through analysis, it is found that the contact stress is concentrated in the layers that are close to the shear plane; the σ11 is much higher than other stress components; most of the stress components conform cosine distribution around the fastener hole; the out-of-plane stress and interlaminate shear stress are quite high in the layers close to the shear plane; the stress distributions of different layers are depended on the ply angles of the specified layer; the effectiveness of the global-local model procedure in reducing the computation effort is obvious and this methodology is applicable to other detailed stress/strain analysis problems in large-scale structures.