Planar defects such as cracks are rarely normal to the loading direction. To investigate the case of arbitrarily oriented cracks mixed mode I/II fracture experiments were conducted on amorphous diamond-like carbon (ta-C) thin films. The mixed mode I/II loading at the crack tip was obtained using oblique edge pre-cracks in uniform gage finite width tensile specimens. The pre-cracks were generated using microindentation in 1μm thick micro-tensile specimens. Uniaxial tensile tests were performed to measure the applied far-field stress at failure and a numerical solution was used to extract the stress intensity factor values. The results were compared against the maximum tensile stress (MTS) and maximum energy release rate (MERR) criteria for mixed mode fracture and the data showed good agreement.

Volume Subject Area:
Microelectromechanical Systems
Topics:
Brittleness, Fracture (Materials), Microelectromechanical systems, Stress, Carbon, Diamonds, Failure, Gages, Tension, Thin films
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