Extension of the Equivalent Material Concept to Compressive Loading: Combination with LEFM Criteria for Fracture Prediction of Keyhole Notched Polymeric Samples

Ali Reza Torabi,Kazem Hamidi,Sergio Cicero,Filippo Berto,Behnam Shahbazian

doi:10.3390/app11094138

Abstract

This work analyzes, both theoretically and experimentally, the fracture process of square specimens weakened by keyhole notches and subjected to compressive stresses. Two materials are covered: general-purpose polystyrene (GPPS) and poly(methyl methacrylate) (PMMA). Firstly, the load-carrying capacity (LCC) of the specimens is determined experimentally. Then, by using the equivalent material concept (EMC) for compressive conditions coupled with the maximum tangential stress (MTS) and the mean stress (MS) criteria, the LCC of the notched specimens is predicted. The results show that by using the approach proposed in the present investigation, not only can the critical loads in the keyhole notched polymeric specimens be precisely predicted, but also the corresponding compressive critical stress of the two mentioned polymers can be successfully estimated.

Highlights

When defects such as U-shaped notches accumulate damage at their tip, leading to the appearance of short cracks, a common repairing method consists of drilling a hole with a radius equal to the crack length
A set of fracture tests were performed on poly(methyl methacrylate) (PMMA) and general-purpose polystyrene (GPPS) keyhole notched specimens with various notch tip radii and subjected to compressive loading
By using the theory of critical distances (TCD), the critical stress and the critical distances of the maximum tangential stress (MTS) and the mean stress (MS) criteria were calibrated by using part of the experimental results and finite element analyses

Summary

Introduction

When defects such as U-shaped notches accumulate damage at their tip, leading to the appearance of short cracks, a common repairing method consists of drilling a hole with a radius (generally) equal to the crack length. This repairing alternative will result in the creation of a keyhole notch if the crack length is greater than the original notch tip radius [1]. In [12,13,18,19], the fracture behaviors of poly(methyl methacrylate) (PMMA) and general-purpose polystyrene (GPPS) have been studied in the presence of different notches and under various loading conditions.

Methods

Results

Conclusion