Experimental Determination of R Curves for European Spruce Using DCB Tests

This paper presents an experimental procedure for obtaining the fracture resistance (R curve) of solid wood specimens made of spruce. Double Cantilever Beam (DCB) tests were performed in order to determine energy release rate vs crack length in Mode I wood fracture (crack opening). Ten wood specimens were loaded using the Universal Testing...

A non-linear finite element approach for the analysis of mode-I free edge delamination in composites

The effect of modified tannic acid (TA) eco-epoxy adhesives on mode I fracture toughness of bonded joints

Two synthesized eco-epoxy components based on TA: (A) glycidyl ether and (B) glycidyl phosphate ester, are used, as a replacement for the Bisphenol A (BPA) based epoxy component, for bonding aluminum (Al) and carbon fiber reinforced polymer (CFRP). Their effect on the mode I fracture toughness (GI) is evaluated by Double Cantilever Beam (DCB)...

The thickness effect of psf nanofibrous mat on fracture toughness of carbon/epoxy laminates

The geometrical features of nanofibers, such as nanomat thickness and the diameter of nanofibers, have a significant influence on the toughening behavior of composite laminates. In this study, carbon/epoxy laminates were interleaved with polysulfone (PSF) nanofibrous mats and the effect of the PSF nanomat thickness on the fracture toughness...

Mode I fracture behavior of glass fiber composite-steel bonded interface: Experiments and CZM

Debonding is characterized as the governing failure mode in the innovative wrapped composite joints made with glass fiber composite material wrapped around steel hollow sections without welding. The prerequisite for predicting debonding failure of wrapped composite joints is to obtain fracture behavior of the composite-steel bonded interface....

Determination Of Mode I Fracture Properties Of European Spruce

In this paper an efficient procedure for obtaining a cohesive law for Mode I timber fracture (crack opening), based on the Double Cantilever Beam (DCB) tests is given. DCB tests were performed on ten European spruce specimens in order to determine the energy release rate vs crack length (R curves). Two crucial parameters - crack length during...

Effect of cyclic aging on mode I fracture energy of dissimilar metal/composite DCB adhesive joints

In some industrial applications, adhesive joints are cyclically exposed to a moist environment, where cyclic moisture absorption and desorption can significantly alter the fracture energy of the bonded joints. Most previous studies are based on monotonic aging conditions, while the performance of bonded joints under cyclic aging is not well...

Role of adherend material on the fracture of bi-material composite bonded joints

The aim of this study is to investigate the effect of the adherend material on the mode I fracture behaviour of bi-material composite bonded joints. Both single-material (steel-steel and composite-composite) and bi-material (steel-composite) joints bonded with a structural epoxy adhesive are studied. Additionally, two adhesive bondline...

Interlaminar toughening approaches for additively manufactured liquid crystal polymers

Liquid crystalline polymers have recently attracted attention for their great tensile properties. However, their interlaminar fracture toughness is low. To solve this, toughening approaches inspired by Nature are applied, exploiting the shaping freedom of fused deposition modelling. Three approaches are studied: the matchstick approach, z...

Critical Parameters in Mode I Interlaminar Fracture Toughness Testing of Thermoplastic Composite Materials

The goal of the thesis (executed for Fokker Aerostructures) was to further the understanding of critical parameters in the DCB test method for thermoplastic composites. The influence of fiber bridging, specimen thickness, insert film thickness, crack length and crack opening rate are investigated by means of experimental DCB tests for...