Abstract
This paper investigates relations between crack growth rate and crack opening levels (as expressed with the stress intensity factor). No relations have been detected for the two different types of load history, studied in this paper. The crack opening level, expressed with the stress intensity factor, is defined as the level where the crack is fully open. This level is detected as the break-point between two straight lines in the load-displacement curve. The first load history contains an overload block in a positive pulsating load. The minimum load is zero during all these tests. During the block the maximum is increased to 125%, 150% or 175% of 15 MPax(m){sup 1/2}. In an additional test the effects of even higher overloads were investigated. In this test the maximum load was increased to 200% of the originally load 17 MPax(m){sup 1/2}, during the overload block. The crack growth rate behaves as the theory predicts, with noticeable acceleration and retardation. The measured stress intensity opening or closure levels do not behave as theory predicts, however. The second load history contains an underload block with the same amplitude as the overload block. The maximum load is kept constant at 15 MPax(m){sup 1/2} and the
More>>
Citation Formats
Johansson, Klas.
Crack closure - an experimental study; Sprickslutning - en experimentell undersoekning.
Sweden: N. p.,
1994.
Web.
Johansson, Klas.
Crack closure - an experimental study; Sprickslutning - en experimentell undersoekning.
Sweden.
Johansson, Klas.
1994.
"Crack closure - an experimental study; Sprickslutning - en experimentell undersoekning."
Sweden.
@misc{etde_10114509,
title = {Crack closure - an experimental study; Sprickslutning - en experimentell undersoekning}
author = {Johansson, Klas}
abstractNote = {This paper investigates relations between crack growth rate and crack opening levels (as expressed with the stress intensity factor). No relations have been detected for the two different types of load history, studied in this paper. The crack opening level, expressed with the stress intensity factor, is defined as the level where the crack is fully open. This level is detected as the break-point between two straight lines in the load-displacement curve. The first load history contains an overload block in a positive pulsating load. The minimum load is zero during all these tests. During the block the maximum is increased to 125%, 150% or 175% of 15 MPax(m){sup 1/2}. In an additional test the effects of even higher overloads were investigated. In this test the maximum load was increased to 200% of the originally load 17 MPax(m){sup 1/2}, during the overload block. The crack growth rate behaves as the theory predicts, with noticeable acceleration and retardation. The measured stress intensity opening or closure levels do not behave as theory predicts, however. The second load history contains an underload block with the same amplitude as the overload block. The maximum load is kept constant at 15 MPax(m){sup 1/2} and the minimum load is decreased from zero to 25%, 50% or 75% of a compressive load of 15 MPax(m){sup 1/2}. In the underload case no predictions for crack rate can be made for the block sequence. The measured stress intensity opening or closure levels do not behave as theory predicts. One possible explanation why the expected relations can not be observed in any of two different load histories, is an inability to accurately measure opening and closure levels with the global technique chosen. 14 refs, 34 figs, 2 tabs}
place = {Sweden}
year = {1994}
month = {Dec}
}
title = {Crack closure - an experimental study; Sprickslutning - en experimentell undersoekning}
author = {Johansson, Klas}
abstractNote = {This paper investigates relations between crack growth rate and crack opening levels (as expressed with the stress intensity factor). No relations have been detected for the two different types of load history, studied in this paper. The crack opening level, expressed with the stress intensity factor, is defined as the level where the crack is fully open. This level is detected as the break-point between two straight lines in the load-displacement curve. The first load history contains an overload block in a positive pulsating load. The minimum load is zero during all these tests. During the block the maximum is increased to 125%, 150% or 175% of 15 MPax(m){sup 1/2}. In an additional test the effects of even higher overloads were investigated. In this test the maximum load was increased to 200% of the originally load 17 MPax(m){sup 1/2}, during the overload block. The crack growth rate behaves as the theory predicts, with noticeable acceleration and retardation. The measured stress intensity opening or closure levels do not behave as theory predicts, however. The second load history contains an underload block with the same amplitude as the overload block. The maximum load is kept constant at 15 MPax(m){sup 1/2} and the minimum load is decreased from zero to 25%, 50% or 75% of a compressive load of 15 MPax(m){sup 1/2}. In the underload case no predictions for crack rate can be made for the block sequence. The measured stress intensity opening or closure levels do not behave as theory predicts. One possible explanation why the expected relations can not be observed in any of two different load histories, is an inability to accurately measure opening and closure levels with the global technique chosen. 14 refs, 34 figs, 2 tabs}
place = {Sweden}
year = {1994}
month = {Dec}
}