# Experimental Study on Fracture Behavior of Adhesive-Bonded Structure with V-notch Based on Digital Gradient Sensing Method

## TL;DR

This paper studies how V-notch angles affect the fracture behavior of adhesive-bonded structures using a digital gradient sensing method.

## Contribution

The study introduces a novel application of the digital gradient sensing method to analyze mode-I fracture behavior in V-notch specimens.

## Key findings

- The V-notch angle significantly influences the fracture load and toughness of both specimen types.
- The bonded specimen showed different fracture behavior compared to the one-piece specimen under mode-I loading.
- Stress intensity factors were calculated using the elasto-optic effect and linear elastic fracture mechanics theory.

## Abstract

In this paper, a comparative study of the mode-I fracture behaviors of two types of specimens with a V-notch defect under plane stress conditions was performed using the digital gradient sensing (DGS) method. First, two types of specimens (namely one-piece specimen and bonded specimen) with the same V-notch defect were both made of polymethyl methacrylate (PMMA), and three different V-notch angles’ defect were considered for each type of specimen. Then, three-point bending tests were performed on both types of specimens. The angular deflection field of light near the V-notch region was recorded using a CCD during the experiments. Finally, by utilizing the relationship between the stress gradient and angular deflection as established by the elasto-optic effect, in conjunction with the principles of linear elastic fracture mechanics theory, the stress intensity factors (SIFs) of two types of specimens under different stress conditions were calculated using the least square method. According to the experimental results, the influence of V-notch angle on fracture load and fracture toughness of two kinds of specimens was discussed. Meanwhile, the experimental results show the significant differences in the fracture behaviors of the two types of specimens under mode-I loading conditions.