A fatigue test based on inclined loading block concept to benchmark delamination growth considering loading history and R-curve effect

The main objective of this paper is to present a delamination benchmark test concept for composite materials that develop non-self-similar delamination in characterization specimens. The non-self-similar delamination is induced by rotating the loading blocks. The simplicity of the test allows for analyzing the loading mode history by...

Analysis of thermoplastic composites and conduction welded joints

Thermoplastic composites enable new manufacturing techniques such as conduction welding to make the aviation industry more sustainable, while at the same time, provide great benefits to cost-efficient high-volume production. One of the benefits of welding is that it reduces the amount of mechanical fasteners required. Fastener-free joining also...

Accurate simulation of delamination under mixed-mode loading using a multilinear cohesive law

The complex failure mechanisms involved in failure of interfaces requires the use of an accurate description of the cohesive law. In recent years, there have been many developments to determine the full shape of the cohesive law. However, most of the existing cohesive zone models assume a simplified shape, such as bilinear, trapezoidal or...

Characterization and analysis of the mode I interlaminar fatigue behaviour of thermoplastic composites considering R-curve effects

Through the application of innovative production processes, thermoplastic composites might help the aviation industry become more sustainable. However, there is currently not much experimental understanding on the fatigue behaviour, and validated analysis methodologies on thermoplastic composites are rather limited. In this work, the fatigue...

Skin-stringer separation in post-buckling of butt-joint stiffened thermoplastic composite panels

Two aeronautical thermoplastic composite stiffened panels are analysed and tested to investigate the buckling behaviour, the skin-stringer separation and the final failure mode. The panels are made of fast crystallising polyetherketoneketone carbon composite, have three stringers with an angled cap on one side, and are joined to the skin by a...

The importance of accounting for large deformation in continuum damage models in predicting matrix failure of composites

The work presented in this paper investigates the ability of continuum damage models to accurately predict matrix failure and ply splitting. Two continuum damage model approaches are implemented that use different stress–strain measures. The first approach is based on small-strain increments and the Cauchy stress, while the second approach...

Characterization and analysis of the interlaminar behavior of thermoplastic composites considering fiber bridging and R-curve effects

Thermoplastic composites can enable the development of new manufacturing techniques to make the aviation industry more sustainable while at the same time greatly benefit cost-efficient and high-volume production. One of the thermoplastic composite materials that can enable this transition is AS4D/PEKK-FC. In this work, the interlaminar...

Experimental analysis and simulation of low-velocity impact damage of composite laminates

The capability to accurately analyse the response of multi-directional composite laminates during impact events is of high importance for the design of lightweight aircraft structures. In this work, both experimental and numerical analyses are performed covering a large design-space of laminates for all aspects from on-set of damage and...

Experimental and numerical evaluation of conduction welded thermoplastic composite joints

The capability of joining two thermoplastic composite parts by welding is a key technology to reduce the weight and cost of assembled parts and enables high volume manufacturing of future aeronautical structures made of thermoplastic composite materials. However, there is not much experimental understanding of the mechanisms involving welded...

Development of a Numerical Framework for Virtual Testing to Support Design of a Next Generation Thermoplastic Multifunctional Fuselage

This work summarizes the recent developments of a numerical framework to predict the mechanical behaviour of thermoplastic composites. It supports the design of a next generation thermoplastic multi-functional fuselage which uses advanced joining techniques such as thermoplastic welding to reduce both weight and cost by limiting the amount of...

Analysis and testing of a thermoplastic composite stiffened panel under compression

This paper presents the numerical analysis of a thermoplastic composite stiffened panel subjected to compression load. The panel has three stringers with a non-symmetric design, with an artificial crack at the middle stringer interface and is made from a fast crystallizing polyetherketoneketone carbon composite. The finite element model...

Virtual testing of thermoplastic composites: Towards a hybrid simulation-physical testing pyramid

This paper summarizes the implementation of a Virtual Testing methodology in an industrial environment to predict the mechanical behaviour of composite material through the different scales of the conventional physical testing pyramid. A robust Virtual Test Lab allows for the generation of virtual allowables, while advanced interface models...