Experimental and Numerical Study on the Tensile Behaviour of UACS/Al Fibre Metal Laminate

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Experimental and Numerical Study on the Tensile Behaviour of UACS/Al Fibre Metal Laminate Jia Xue & Wen-Xue Wang & Jia-Zhen Zhang & Su-Jun Wu & Hang Li

Received: 6 August 2014 / Accepted: 2 September 2014 # Springer Science+Business Media Dordrecht 2014

Abstract A new fibre metal laminate fabricated with aluminium sheets and unidirectionally arrayed chopped strand (UACS) plies is proposed. The UACS ply is made by cutting parallel slits into a unidirectional carbon fibre prepreg. The UACS/Al laminate may be viewed as aluminium laminate reinforced by highly aligned, discontinuous carbon fibres. The tensile behaviour of UACS/Al laminate, including thermal residual stress and failure progression, is investigated through experiments and numerical simulation. Finite element analysis was used to simulate the onset and propagation of intra-laminar fractures occurring within slits of the UACS plies and delamination along the interfaces. The finite element models feature intralaminar cohesive elements inserted into the slits and inter-laminar cohesive elements inserted at the interfaces. Good agreement are obtained between experimental results and finite element analysis, and certain limitations of the finite element models are observed and discussed. The combined experimental and numerical studies provide a detailed understanding of the tensile behaviour of UACS/Al laminates. Keywords Fibre metal laminate . Discontinuous reinforcement . Tensile test . Finite element analysis . Cohesive zone modelling

1 Introduction Formability of carbon fibres during fabrication is important for applications involving complex shaped components for carbon fibre reinforced polymer (CFRP) [1]. J. Xue (*) : J. > < t ¼ ð1−DÞKδ; > > > > : t ¼ 0;

D¼0

if 0≤δ ≤δ0

ðIntactÞ

δ δ−δ D ¼  f 0 δ δ −δ

if δ0 ≤δ ≤δ f

ðSoftening Þ

D¼1

if δ > δ f

ðFailed Þ

 f

 0

ð1Þ

In a real structure, mixed-mode loading is usually present at the crack front, and the onset of delamination may occur before any of the tractions reach their corresponding interfacial strength. In consideration of mixed-mode loading, a quadratic nominal stress criterion, given below, was used in this study to simulate the onset of delamination. 

t Intact

htzz i toZZ

2

 þ

tzx tozx

2

D=0

þ

tzy tozy

!2 ¼1

Softening

ð2Þ

D=1

Failed

tzzo Kzz GIC

δzzo

δzzf

δ

Fig. 3 Bilinear traction-relative displacement cohesive law for mode I loading (mode II and III are similar)

Appl Compos Mater

where the Macauley bracket, 〈tzz〉, is defined as 〈tzz〉=0 if tzz ≤0 and 〈tzz〉=tzz if tzz >0. The Benzeggagh-Kennane Law was used to simulate the mixed-mode delamination propagation. The mixed-mode interfacial facture toughness, Gc is given as 8  π GS > > < Gc ¼ Gic þ ðGIIC −GIC Þ GT ð3Þ G ¼ Gt zz þ Gt zy > > : S Gr ¼ Gs þ Gt zz where is the work done by two shear tractions and their corresponding relative displacements, while is the total work done. The mixed-mode parameter η, is a constant. The material properties of the cohesive element are summarized in Table 2. There is no con