A systematic investigation is carried out on how different parameters influence stress and strain concentration factors (SCF and SNCF) in a composite plate with a hole under uniaxial tension. Flat and singly curved composite plates have been modelled in ANSYS 15.0. The governing parameter includes: (i) size, shape and eccentricity of hole, (ii) number of plies, (v) fiber orientation and (vi) plate curvature. It is observed that different parameters influence the SCF and SNCF with varying degrees. For example, SCF may be as high as 7.16 for a square shaped hole. Also, SCF and SNCF are found to be approximately same in most of the cases. Finally, simplified design formulas are developed for evaluation of SCF for a wide range of hole size, eccentricity and fiber orientation.
Advanced composite polymer matrix and their different manufacturing processes tend to develop pores of varying size and play a major limiting role in residual stress, damage initiation, matrix cracking, strength, and durability. Direct imaging or simulations to understand the pore formation mechanism in the viscous polymer is difficult. Ultimately, the mechanical performance of the solidified matrix needs better prediction. This paper presents a stochastic micromechanical model, including the effect of pores' formation on the polymer matrix's elastic properties. Theoretical homogenization based micromechanical models for polymer composites is reviewed in the first part. Later, a micromechanical model is proposed considering the different stages of pore formation in a polymer matrix. Polymer samples are fabricated for determining the pore distribution parameters and used appropriately in the proposed model to estimate the elastic properties for a given distribution and volume fraction of the pores. A modified Mori‐Tanaka homogenization approach and a differential scheme of inclusion of pores are incorporated in the model. Results obtained from the proposed model are compared with the experimental measurements, and a significant correlation is found.
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