Failure Analysis of Adhesively Bonded Structures: From Coupon Level Data to Structural Level Predictions and Verification

This paper presents a predictive methodology and verification through experiment for the analysis and failure of adhesively bonded, hat stiffened structures using coupon level input data. The hats were made of steel and carbon fiber reinforced polymer composite, respectively, and bonded to steel adherends. A critical strain energy release rate criterion was used to predict the failure loads of the structure. To account for significant geometrical changes observed in the structural level test, an adaptive virtual crack closure technique based on an updated local coordinate system at the crack tip was developed to calculate the strain energy release rates. Input data for critical strain energy release rates as a function of mode mixity was obtained by carrying out coupon level mixed mode fracture tests using the Fernlund–Spelt (FS) test fixture. The predicted loads at failure, along with strains at different locations, were compared with those measured from the structural level tests. The predictions were found to agree well with measurements for multiple replicates of adhesively bonded hat-stiffened structures made with steel hat/adhesive/steel and composite hat/adhesive/steel, thus validating the proposed methodology for failure prediction.

[1]  Satya N. Atluri,et al.  Structural Integrity & Durability , 1997 .

[2]  De Xie,et al.  Strain energy release rate calculation for a moving delamination front of arbitrary shape based on the virtual crack closure technique. Part I: Formulation and validation , 2006 .

[3]  G. Fernlund,et al.  Mixed Mode Energy Release Rates for Adhesively Bonded Beam Specimens , 1994 .

[4]  Zhigang Suo,et al.  The role of material orthotropy in fracture specimens for composites , 1992 .

[5]  K. Liechti,et al.  Shear induced toughening in bonded joints: experiments and analysis , 2002 .

[6]  Xinran Xiao,et al.  Stiffness prediction of the double lap shear joint. Part 2: Finite element modeling , 2004 .

[7]  Xinran Xiao,et al.  Stiffness prediction of the double lap shear joint. Part1: Analytical solution , 2004 .

[8]  De Xie,et al.  Computation of Energy Release Rates for Kinking Cracks based on Virtual Crack Closure Technique , 2004 .

[9]  De Xie,et al.  Fracture criterion for kinking cracks in a tri-material adhesively bonded joint under mixed mode loading , 2005 .

[10]  De Xie,et al.  Progressive crack growth analysis using interface element based on the virtual crack closure technique , 2006 .

[11]  Ronald Krueger,et al.  The Virtual Crack Closure Technique : History , Approach and Applications , 2002 .

[12]  L. Banks‐Sills,et al.  Fracture testing of Brazilian disk sandwich specimens , 2002 .

[13]  Zhigang Suo,et al.  Experimental determination of interfacial toughness curves using Brazil-nut-sandwiches , 1990 .

[14]  Z. Suo,et al.  Mixed mode cracking in layered materials , 1991 .

[15]  M. Kanninen,et al.  A finite element calculation of stress intensity factors by a modified crack closure integral , 1977 .

[16]  John H. Crews,et al.  The mixed-mode bending method for delamination testing , 1989 .

[17]  Z. Suo,et al.  Interface crack between two elastic layers , 1990 .

[18]  H. Chai.  On the correlation between the mode I failure of adhesive joints and laminated composites , 1986 .

[19]  Jan K. Spelt,et al.  Mixed-mode fracture characterization of adhesive joints , 1994 .

[20]  J. K. Spelt,et al.  The effect of geometry on the fracture of adhesive joints , 1994 .

[21]  Jr. J. Crews,et al.  Mixed-Mode Bending Method for Delamination Testing , 1990 .

[22]  K. N. Shivakumar,et al.  A virtual crack-closure technique for calculating stress intensity factors for cracked three dimensional bodies , 1988, International Journal of Fracture.

[23]  Herzl Chai,et al.  Observation of deformation and damage at the tip of cracks in adhesive bonds loaded in shear and assessment of a criterion for fracture , 1993, International Journal of Fracture.