Numerical Modelling of Skin-Stringer Separation in Thermoplastic Composite Stiffened Panels

This thesis project focuses on the evaluation of the Extended Finite Element Model (XFEM) for modelling skin-stringer separation in thermoplastic composite stiffened panels. The study uses test results from a reference study in the literature on a PEKK-FC carbon composite panel with three stringers joined to the skin using a short-fibre...

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....

Characterization of Mixed-Mode Fracture Behaviour of Thermoplastic Composite Materials by Mandrel Peel Test

Delamination is a significant failure mode that has been the subject of extensive research in laminated structures. The interface in assembly structures often represents the susceptibly weak link and necessitates careful consideration to guarantee structural stability. It is of utmost significance to understand the behaviour of the delamination...

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...

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...

Promoting extrinsic bridging of adhesively-bonded CFRP joints through the adhesive layer architecture

Carbon fiber-reinforced polymers (CFRPs) have widely attracted the aerospace and automotive industries due to high stiffness and lightweight. Secondary adhesive bonding of CFRPs is a promising research field to fully explore their potential. However, multiple challenges have limited the further application of adhesively-bonded composite joints...

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...

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)...

Enhancing the mechanical properties of fused filament fabricated parts by elevating the print room temperature

Additive manufacturing (AM) is currently making a transition from mainly being used for prototyping to an alternative for conventional production methods. AM provides more freedom in design geometry combined with the possibility to produce (complex) products in low quantities. As a result, the need arises for printed parts with consistent...

On the fracture behaviour of CFRP bonded joints under mode I loading: Effect of supporting carrier and interface contamination

This paper addresses the fracture behaviour of bonded composite plates featuring a kissing bond along the crack growth path. Double cantilever beam (DCB) experiments are carried out under a displacement controlled loading condition to acquire the load response. The experimental data are collected and analysed analytically for specimens with...

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...

Characterization of multi-GNSS between-receiver differential code biases using zero and short baselines

Care should be taken to minimize adverse impact of receiver differential code biases (DCBs) on global navigation satellite system (GNSS)-derived ionospheric parameters. It is therefore of importance to ascertain the intrinsic characteristics of receiver DCBs, preferably in the context of new-generation GNSS. In this contribution, we present a...

An investigation on hybrid interface using on-line monitoring experiment and finite element analyses

In this work, the hybrid interface between metal and thermosetting polymer matrix composite was studied via experimental and numerical investigations. Hybrid laminates, whose constituents are aluminum foil, carbon fabric and epoxy matrix, were manufactured using the vacuum assisted resin transfer molding process. Chromic anodization was used to...