The effects of open holes on the fracture behaviors and mechanical properties of glass fiber mat composites

Abstract

In this paper, composite specimens were fabricated from a glass fiber chopped strand mat and unsaturated polyester resin using the hand lay-up method. To evaluate the effects of open holes on the mechanical properties, different factors, including the volume fraction of glass fiber and material thickness were investigated. Both the unnotched strength of smooth specimens and the notched strength of specimens with holes, increased as volume fraction increased, but the trends were different. For notched specimens with closer volume fractions, increased thickness or width-to-depth ratio led to a lower resistance on the open hole. In investigating the fracture behaviors of notched specimens, two different fracture areas were distinguished: parallel areas and fan-shaped areas. The length of each parallel area was measured. To evaluate the material properties, characteristic distance was calculated using linear elastic methods in finite element software (MSC-Marc, MSC Software Corporation, Tokyo, Japan). The results revealed that characteristic distance has a good correspondence with parallel area length.

Keywords

• characteristic distance
• finite element
• glass fiber chopped mat
• notched strength