Analysis of tensile damage characteristics of single filled bolt hole in laminate

Abstract

The strength of filled bolt holes of composites is an important parameter in developing the bearing bypass envelope curves for bolted joint structures in engineering design. This paper presents the procedures of tensile failure strengths and damage for a laminate with a filled bolt hole. Tests of two different cases, open‐hole tension (OHT) and filled‐hole tension (FHT), were performed and repeated seven times, respectively. A new type of virtual testing based on the LaRC05 criteria coupling with XFEM crack technique was developed to predict and analyze the crack initiation and early propagation around the bolt hole in the laminates. Two analytical methods were also adopted to predict the residual strength for a laminate after drilling. The results show that the thinner sample would present a higher strength with the same material system. It is also shown that the virtual test can well capture the failure modes, revealing that the 0° fiber has a natural function of crack arrest, the 90° layers that are the fracture pioneers with matrix tensile failure trigger the fiber breakage of 0° layers, and the failure of 45° layers occurs at the last. Additionally, an interesting phenomenon is observed that the initial failure around the filled hole edge does not affect the structural stiffness. Finally, a good agreement is achieved among the experimental, analytical and numerical results. It suggests that the results could provide a valuable guidance for the design of multi‐bolted joint structure.

Prediction of pseudo‐ductility and structural optimization of nacre‐inspired carbon fiber‐reinforced polymer laminate

“…At present, there are many criterions for judging the failure of unidirectional specimens, such as maximum stress failure criterion, maximum strain failure criterion, Hashin failure criterion and so on. [32][33][34][35] Besides that, the two-dimensional Chang-Chang failure criterion, a commonly used failure criterion, did not take into account the effects of out-of-plane stress. Therefore, in this paper the three-dimensional Chang-Chang failure criterion was chosen to predict the tensile properties and damage modes of discontinuous FRP specimens.…”

“…At present, there are many criterions for judging the failure of unidirectional specimens, such as maximum stress failure criterion, maximum strain failure criterion, Hashin failure criterion and so on 32–35 . Besides that, the two‐dimensional Chang‐Chang failure criterion, a commonly used failure criterion, did not take into account the effects of out‐of‐plane stress.…”

Numerical modeling on load bearing and bypass behavior of bolted single lap joints of laminates

“…Over the past several decades, in order to balance the efficiency, in terms of cost and accuracy, there have been various FEM models developed to simulate the mechanical behavior of bolted joints. In general, these models can be divided into macroscale, 1,11,12,43 mesoscale, 15,44,45 and multi-scale models, 46 corresponding to 1D, 2D, and 3D models, respectively. Compared with the latter two models, the 1D beam model is the first model used for the aircraft structural design 47 in the initial design stage of the design.…”