Experimental simulation of propagating paths of fatigue cracks near or across the interface of bonded dissimilar materials by using the proposed equivalent specimens

摘要

A method of simulating the behavior of fatigue cracks propagating in bonded dissimilar materials by using equivalent specimens made of single constituent material was proposed. The equivalent specimens reproduced the same elastic characteristics with those of the bonded dissimilar materials by replacing the effect of elastic constant by that of the specimen thickness, and removed the effect of weakened strength of the bonded interface. Using the proposed equivalent specimens, experiments were conducted simulating fatigue crack paths propagating near or across the slant (15 and 45°) interface of bonded steel-copper specimens. When the cracks propagated from the thick (equivalent to steel) side to the thin (copper) side, they grew almost straight across the interface, while the initial cracks were in the thin (copper) side, they propagated along the interface without penetrating into the thick (steel) side. These behaviors were quite similar to the actual ones directly observed with the real bonded steel-copper specimens. The proposed concept of the equivalent specimen was confirmed to be useful in simulating the behavior of fatigue cracks in bonded dissimilar materials.