Comparative study on metal/CFRP hybrid structures under static and dynamic loading

This paper aims to explore the dynamic responses and crashing characteristics of double hat shaped tubes made of weave carbon fiber reinforced plastic (CFRP). Experimental investigations were carried out into three different thicknesses and lengths of the composite tubes fabricated by the bladder molding process. Three distinct failure modes, classified as progressive end crushing, mid-length collapse and overlap opening, were observed in the dynamic crushing tests. Unlike continuous splaying fronds observed in the quasi-static tests, dynamic tests exhibited a number of fragment segments in the progressive end crushing mode. It is shown that the ply number was a critical parameter affecting the failure mode and energy absorption capability. The increase in ply number led to increases in the peak load and specific energy absorption (SEA); whereas the tubal length seemed insensitive to energy absorption capability. Compared to the quasi-static cases, the dynamic impact tests resulted in the higher peak load (increased from 46 % to 125 %) and lower SEA (reduced from 21 % to 33 %) for the tested tubes.

Experimental investigation into dynamic axial impact responses of double hat shaped CFRP tubes

https://pureadmin.qub.ac.uk/ws/files/85124165/Manuscript_revision_Accepted_Version_POST_PRINT.pdf

Modelling the crush behaviour of thermoplastic composites

Theory-guided machine learning for damage characterization of composites

Dynamic behaviour of composite adhesive joints for the automotive industry

In crash simulations of composite aircraft fuselage sections, frame breaking, skin bending and failure of mechanically fastened joints can typically be identified as major contributors to crash energy absorption. In order to generate a database for model validations, corresponding static and dynamic tests have been performed on coupon and structural element level to characterise the rate-dependent failure behaviour and energy absorption. Skin-bending, frame-bending and joint-failure tests under pull-out, bearing and peeling loads were performed on 977-2/HTS carbon fibre/epoxy specimens. On the one hand, effects of loading rate on the frame-bending behaviour could be observed. On the other hand, fastener failure did not appear to be depending on loading rate for the test speeds up to 10 m/s involved in this study. Adequate modelling methods in Abaqus/Explicit were derived and validated, and finally applied to a global aircraft crash simulation model.

Dynamic testing and modelling of composite fuselage frames and fasteners for aircraft crash simulations

Experimental study of CFRP components subjected to dynamic crash loads

Simulation of CFRP components subjected to dynamic crash loads

Comparison of two progressive damage models for studying the notched behavior of composite laminates under tension

Crashworthiness research for transport aircraft fuselage structures becomes more important particularly with regard to the increasing use of CFRP in primary structures. Whereas today s aluminium fuselage structures offer sufficient crashworthiness purely due to the ductile behaviour of metal, the brittle behaviour of a CFRP fuselage structure implicates the risk of uncontrolled failure with little energy absorption. Certification rules (special conditions) demand a crashworthiness of CFRP fuselages to be equivalent to that of a standard aluminium fuselage of the same size. To comply with these special conditions a specific crash design has to be developed for a CFRP fuselage structure. This involves the definition of trigger mechanisms, energy absorbing devices and their positioning in the fuselage and may lead to a mass increase of the structure. The basis for the definition of the structural crash devices is a crash scenario assessment on fuselage section level. This approach considers a crash velocity purely in vertical direction. This simplified crash condition was selected to perform most of the previous crash tests on metallic fuselage structures and represents the basis for current certification routes. For the numerical assessment of crash scenarios a Kinematics Model was developed based on commercial explicit finite element method. The essential of the Kinematics Model is the potential to define the behaviour of structural crash devices by characteristic input curves using macro elements in the frames, vertical struts and the sub-cargo structure (see Figure). Only by varying the loaddeformation characteristics of the crash devices different crash scenarios can be defined, assessed and compared to each other. Different potential crash scenarios for narrow-body fuselage structures were analysed using this modelling approach. Based on the finally selected crash scenario a pre-sized composite fuselage structure was re-sized to minimize the crash loads on passengers and structure and following to minimize the mass penalty.

/pdf/the-kinematics-model-a-numerical-method-for-the-development-1g5wb89y1g.pdf

Matthias Waimer

Papers

Dynamic testing and modelling of composite fuselage frames and fasteners for aircraft crash simulations

Experimental study of CFRP components subjected to dynamic crash loads

Simulation of CFRP components subjected to dynamic crash loads

Comparison of two progressive damage models for studying the notched behavior of composite laminates under tension

The Kinematics Model - A Numerical Method for the Development of a Crashworthy Composite Fuselage Design of Transport Aircraft