Study of the Onset of Permanent Deformation in Structurally Bonded Joints.
Final rept. 29 Jun 70-31 Dec 71,
AUBURN UNIV ALA DEPT OF MECHANICAL ENGINEERING
Pagination or Media Count:
The fracture toughness of aluminum-epoxy- aluminum samples in the lap-shear configuration is studied by the strain energy release rate approach. Specific effects of curing cycle, adhesive modulus, and sample dimensions are studied and reported. The fracture surface appearance is studied by optical, electron microscope, and scanning electron microscope techniques in order to better characterize the nature of the failure processes. The result is a general confirmation of the Mode I crack extension and an identification of two distinct regions in each loading zone where the crack extension is first slow and later rapid. Recommendations are made for the improvement of the fracture toughness test method by means of establishing a family of elastic compliance curves for the lap shear samples to eliminate the distracting effects of non-elastic deformation processes and for a procedure for measurement of the critical crack size at the onset of rapid elastic crack extension. Author-PL
- Couplers, Fasteners and Joints