A FATIGUE CRACK CLOSURE MECHANISM IN TITANIUM

Fatigue and Fracture of Engineering Materials and Structures - Tập 1 Số 1 - Trang 135-148 - 1979
N. Walker1, C.J. Beevers2
1Department of Chemistry, Birmingham University, P.O. Box 363, Birmingham, B15 2TT, England
2Department of Physical Metallurgy and Science of Materials, Birmingham University

Tóm tắt

Abstract— Fatigue crack closure in commercial titanium has been investigated by examining the crack profile using a two‐stage replica technique and by monitoring the crack raouth opening displacement. The replicas show that when closure occurs the crack does not close back from the crack tip but at discrete contact points along the crack faces. The observed closure mechanism is therefore quite different from the generally accepted model. Assuming that the contact points wedge the crack open, the stress intensity at the minimum load is greater than expected and the range of the stress intensity is effectively reduced. Also, it was found that the crack growth rates measured in the range 0·05 ≦R≦ 0·7 showed a singular dependence on the parameter Δθ which for SEN specimens approximates to the change in angle subtended by the crack faces. It is therefore suggested that there is a direct link between Δθ and the effective stress intensity amplitude.

Từ khóa


Tài liệu tham khảo

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Fatigue and Fracture of Engineering Materials and Structures

Tập 1 Số 1

135-148

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