Precise control design method for breaking load under wide temperature range and large loading rate

Abstract

The invention belongs to the technical field of material load strength, and particularly relates to a design method for accurate control of a breaking load under a wide temperature range and a large loading rate, and the method comprises the steps: obtaining the breaking load of a test piece under a standard working condition; obtaining a breaking load of the test piece when the loading rate is greater than the standard working condition; obtaining a breaking load of the test piece when the temperature is greater than or less than the standard working condition; judging whether the magnitude of the loading rate and the magnitude of the temperature have positive influence or negative influence on the magnitude of the breaking load; carrying out a superposition test on factors with the same direction influence, and obtaining a positive influence value and a negative influence value on the breaking load under the superposition of the loading rate and the temperature; subtracting the forward influence value from the upper limit value of the breaking load demand range to obtain an upper limit value of a breaking load design range; adding the negative influence value to the lower limit value of the breaking load demand range to obtain a lower limit value of a breaking load design range; and based on the upper limit value and the lower limit value of the breaking load design range, designing a breaking workpiece by adopting the same material as the test piece.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material load strength, and particularly relates to a design method for accurately controlling a tensile breaking load under a wide temperature range and a large loading rate. BACKGROUND

[0002] In the fields of aviation, aerospace, automobile and engineering machinery, a shear bolt with a notch is mainly used to trigger a throwing / launching function to realize physical separation in an emergency. Due to the constraint of the notch, the stress state at the minimum cross section changes from uniaxial shear to triaxial stress, the load fluctuation range is wide, and the tensile breaking load cannot be accurately controlled, especially under a wide temperature range and a large loading rate, the load fluctuation range is multiplied. Therefore, the shear bolt cannot meet the use requirements of a wide temperature range, a large loading rate and high-precision release. Therefore, the design method for accurately controlling the tensile breaking load under a wide temperature range and a large loading rate is extremely important. SUMMARY

[0003] In order to solve the above problems, the application provides a design method for accurately controlling a tensile breaking load under a wide temperature range and a large loading rate, comprising the following steps.

[0004] Obtaining a tensile breaking load of a test piece under a standard working condition;

[0005] Obtaining a tensile breaking load of the test piece when the loading rate is greater than that under the standard working condition;

[0006] Obtaining a tensile breaking load of the test piece when the temperature is greater than and less than that under the standard working condition;

[0007] Judging whether the size of the loading rate and the height of the temperature positively or negatively affect the size of the tensile breaking load;

[0008] Performing superposition tests on factors with the same direction of influence to obtain positive and negative influence values of the loading rate and the temperature on the tensile breaking load under superposition;

[0009] Subtracting the positive influence value from the upper limit value of the tensile breaking load requirement range to obtain an upper limit value of a tensile breaking load design range;

[0010] Adding the negative influence value to the lower limit value of the tensile breaking load requirement range to obtain a lower limit value of the tensile breaking load design range;

[0011] Designing a tensile breaking workpiece by using the same material as the test piece based on the upper and lower limit values of the tensile breaking load design range.

[0012] Preferably, the upper limit value of the design range is subtracted by a safety margin, and the upper limit value of the design range is added by the safety margin.

[0013] Preferably, the safety margin is determined by machining precision.

[0014] Preferably, when the workpiece needs surface treatment, the surface treatment influence on the pull-off load is determined by experiment, when the surface treatment has positive influence on the pull-off load, the upper limit value of the design range is reduced by the surface treatment influence on the pull-off load, and when the surface treatment has negative influence on the pull-off load, the lower limit value of the design range is increased by the surface treatment influence on the pull-off load.

[0015] The present application can determine the factors influencing the size of the pull-off load, including material, temperature range, loading rate and surface treatment process, and reasonably design the pull-off workpiece based on the factors. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is a preferred embodiment of the present application Wide temperature range and large loading rate under the flow chart of pull-off load precise control design method;

[0017] Fig. 2 is a preferred embodiment of the present application Influence factor proportion chart.

[0018] Fig. 3 is a preferred embodiment of the present application Application example workpiece schematic diagram. DETAILED DESCRIPTION

[0019] In order to make the technical scheme of the present application and its advantages clearer, the technical scheme of the present application will be further described in detail below with reference to the drawings. It should be understood that the specific embodiments described herein are only part of the embodiments of the present application, which are used to explain the present application, but not to limit the present application. It should be noted that, for the purpose of description, only parts related to the present application are shown in the drawings, and other related parts can be referred to the general design. In the case of no conflict, the embodiments in the present application and the technical features in the embodiments can be combined to obtain new embodiments.

[0020] The present application provides a wide temperature range and large loading rate under the flow chart of pull-off load precise control design method, comprising:

[0021] Obtain the pull-off load of the test piece under the standard working condition;

[0022] Obtain the pull-off load of the test piece when the loading rate is greater than the standard working condition;

[0023] Obtain the pull-off load of the test piece when the temperature is greater than and less than the standard working condition;

[0024] Determine whether the size of the loading rate and the height of the temperature have positive or negative influence on the size of the pull-off load;

[0025] The factors with the same direction influence are superimposed to obtain the positive and negative influence values of the loading rate and the temperature on the pull-off load;

[0026] Subtracting the positive influence value from the upper limit value of the tensile load requirement range to obtain the upper limit value of the tensile load design range;

[0027] Adding the negative influence value to the lower limit value of the tensile load requirement range to obtain the lower limit value of the tensile load design range;

[0028] Based on the upper limit value and the lower limit value of the tensile load design range, a tensile workpiece is designed using the same material as the test piece.

[0029] Preferably, the upper limit value of the design range is reduced by a safety margin, and the upper limit value of the design range is added to the safety margin.

[0030] Preferably, the safety margin is determined by the machining accuracy.

[0031] Preferably, when the workpiece needs surface treatment, the influence of surface treatment on the tensile load is determined by the test, when the surface treatment has a positive effect on the tensile load, the upper limit value of the design range is reduced by the influence of the surface treatment on the tensile load, and when the surface treatment has a negative effect on the tensile load, the lower limit value of the design range is added to the influence of the surface treatment on the tensile load.

[0032] The present application can determine the factors affecting the size of the tensile load, including material, temperature range, loading rate and surface treatment process, and reasonably design the tensile workpiece based on the factors.

[0033] As shown in Figs. 1-3 A specific fact way, comprising:

[0034] First: clearly input conditions, in the range of-55℃-70℃, the maximum loading rate is 2000kN / s, and the tensile load under the above conditions is required to meet (160-176)kN, and the load fluctuation range is 0-10%, Fig. 2 F=160kN, η=1.1, and the part material is 30CrMnSiA.

[0035] Second: through the maximum loading rate influence test on the tensile load, it is determined that the large loading rate will make the tensile load increase, and the large loading rate will make the tensile load increase by about 1%;

[0036] Third: through the temperature influence test on the tensile load, it is determined that low temperature will make the tensile load increase by about 2%, and high temperature will make the tensile load decrease by about 1.5%;

[0037] Fourth: it is determined that low temperature and large loading rate make the tensile load increase by about 3%, η-γ=0.03. High temperature and slow loading make the tensile load decrease by about 1.5%, α-1=0.015;

[0038] Fifth: determine the impact factor proportion, α-1 = 0.015 (high temperature influence, A area), η-γ = 0.03 (low temperature and loading rate influence, D area).

[0039] Sixth: C area γ-β = 0.055, which is used for Fig. 3 The size ΦD and Φd tolerance and machining equipment precision, etc. as shown;

[0040] Seventh: β-α = 0.01 (certain allowance area, B area), which is used for the influence of surface treatment on the tensile load.

[0041] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A design method for precise control of tensile-breaking load under wide temperature range and high loading rate, characterized in that, include: Obtain the tensile load of the test specimen under standard operating conditions; Obtain the tensile load of the test specimen when the loading rate is greater than that under standard conditions; Obtain the tensile load of the test specimen when the temperature is greater than or less than the standard operating condition; Determine whether the loading rate and temperature have a positive or negative impact on the tensile load. Superimposed tests were conducted on factors with the same directional influence to obtain the positive and negative influence values ​​of loading rate and temperature on tensile load. The upper limit of the tensile load design range is obtained by subtracting the positive influence value from the upper limit of the tensile load requirement range. The lower limit of the tensile load design range is obtained by adding the negative influence value to the lower limit of the tensile load requirement range. Based on the upper and lower limits of the tensile load design range, the workpiece is designed to break using the same material as the test piece.

2. The design method for precise control of tensile-breaking load under wide temperature range and high loading rate as described in claim 1, characterized in that, Subtract the safety margin from the upper limit of the design range, and add the safety margin to the upper limit of the design range.

3. The design method for precise control of tensile-breaking load under wide temperature range and high loading rate as described in claim 1, characterized in that, The safety margin is determined by the machining accuracy.

4. The design method for precise control of tensile-breaking load under wide temperature range and high loading rate as described in claim 2, characterized in that, When a workpiece requires surface treatment, the impact of the surface treatment on the tensile load is determined through experiments. If the surface treatment has a positive impact on the tensile load, the upper limit of the design range is reduced by the impact of the surface treatment on the tensile load. If the surface treatment has a negative impact on the tensile load, the lower limit of the design range is added to the impact of the surface treatment on the tensile load.

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