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Rapid evaluation method for low-cycle fatigue performance of ultrathin automobile steel plate

A low-cycle fatigue and automotive steel plate technology, applied in the direction of strength characteristics, measuring devices, instruments, etc., can solve the problems of the influence of the accuracy of test results and the increase of material consumption, and achieve the effect of simple and fast testing process and saving experimental materials

Active Publication Date: 2019-01-18
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method not only increases the amount of material by five times, but also the use of adhesive between steel plates is easy to affect the accuracy of test results
In addition, some researchers have carried out uniaxial tension-compression fatigue loading experiments by designing different anti-buckling devices or using non-contact strain measurement methods, but there are still problems such as how to measure strain and the accuracy of strain measurement.

Method used

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  • Rapid evaluation method for low-cycle fatigue performance of ultrathin automobile steel plate
  • Rapid evaluation method for low-cycle fatigue performance of ultrathin automobile steel plate
  • Rapid evaluation method for low-cycle fatigue performance of ultrathin automobile steel plate

Examples

Experimental program
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Effect test

Embodiment 1

[0090] Carry out cantilever beam symmetrical bending fatigue loading on a DP590 steel sheet with an original thickness of 2 mm, determine the thickness range of the cantilever beam bending fatigue loading sample according to step S1, and design the thin foil size according to step S11: 1:11mm, l 0 : 3mm, w: 3.5mm, measure the average grain size of ferrite as d=9.5μm; calculate the number of grains passing through the first stage of fatigue crack propagation by step S12, Y≈1, σ y '≈400MPa, Δσ value is about 400~450MPa, calculated as i=3~4; from step S13, if the plate is subjected to tension-compression symmetric fatigue loading, calculate the number of grains that the crack propagates through in the second stage j≈2000 / 9.5≈210; combined with steps S14, S15 and S16, the value range of m is 2.5-4, and the calculated thickness range of the thin foil sample is t=60-160 μm. Then proceed to step S2, from step S21, select the thin foil thickness as 50 μm, 100 μm, 150 μm, 200 μm; est...

Embodiment 2

[0092] Carry out cantilever beam symmetrical bending fatigue loading on a DP steel sheet for automobiles with an original thickness of 2mm and a martensite volume fraction of 14%, determine the thickness range of the cantilever beam bending fatigue loading sample according to step S1, and design according to step S11 Thin foil size: l: 11mm, l 0 : 3mm, w: 3.5mm, measure the average grain size of ferrite as d=9.5μm; calculate the number of grains passing through the first stage of fatigue crack propagation by step S12, Y≈1, σ y '≈400MPa, Δσ value is about 400~450MPa, calculated as i=3~4; from step S13, if the plate is subjected to tension-compression symmetric fatigue loading, calculate the number of grains that the crack propagates through in the second stage j≈2000 / 9.5≈210; combined with steps S14, S15 and S16, the value range of m is 2.5-4, and the calculated thickness range of the thin foil sample is t=60-160 μm. Then proceed to step S2, from step S21, select thin foil th...

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Abstract

The invention relates to a rapid evaluation method for a low-cycle fatigue performance of ultrathin automobile steel plate. By the method, the low-cycle fatigue lifetime of the material is evaluated according to a fatigue lifetime test result of a thin foil sample of the plate under a symmetric flexural fatigue loading method of cantilever, and the evaluation of strain control fatigue loading andfatigue lifetime of the ultrathin automobile steel plate is achieved by building a relation between the flexural deflection of the thin foil sample and maximum stress and selecting a thickness of thethin foil sample. By the method, the fatigue cycle lifetime of the ultrathin automobile steel plate under a large strain condition can be tested, and the rapid evaluation method is provided for the low-cycle fatigue lifetime test which is difficult to acquire under an axial pull-press fatigue loading condition of the ultrathin automobile steel plate. The method can be further expanded and appliedto low-cycle fatigue performance evaluation of the other ultrathin metal plates of which axial pull-press fatigue loading experiments are difficult to perform.

Description

technical field [0001] The invention belongs to the technical field of steel plate low-cycle fatigue performance measurement, and relates to a rapid evaluation method for low-cycle fatigue performance of ultra-thin automotive steel plates. Background technique [0002] Among the materials used in automobiles, the amount of steel plates accounts for a considerable proportion. With the introduction of the concept of automobile lightweight, the industry reduces the thickness of the steel plate to reduce the weight of the car body, thereby reducing power consumption such as oil and electricity, and at the same time reducing automobile exhaust emissions and energy consumption. However, the thinning of automotive plates poses challenges to the strength, toughness, impact resistance and fatigue resistance of materials, especially the impact of the fatigue resistance of automotive plates on the safety of automobiles in service, and with the reduction of steel plate thickness, The e...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/32
CPCG01N3/32G01N2203/0066G01N2203/0073
Inventor 张滨马振华
Owner NORTHEASTERN UNIV
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