薄壁与厚壁管材力学性能的统一评价方法——广义缺口环法

Unified Determination Method for Mechanical Properties of Thin-walled and Thick-walled Tubes——General Split Ring Method

管材作为一类重要的材料制品结构形式,其力学性能的准确测试对于保障管材构件服役安全性与可靠性至关重要。目前所提出的缺口环法为测试管材力学性能提供了可行方案,但缺口环法测试管材弹性模量与弯曲强度的计算公式仅适用于薄壁管材。为实现厚壁管材力学性能的准确测试,本研究将径向力与切向力对管材试样的变形能考虑在内,基于曲杆分析理论,提出了适用范围更广的广义缺口环法。以三点弯曲法测得的石英玻璃梁试样弹性模量(72.08±1.87GPa)与弯曲强度(73.84±6.67 MPa)作为参比,分别利用缺口环法与广义缺口环法测得了同一批次石英玻璃管材试样的弹性模量与弯曲强度,测试结果表明:随着管材壁厚的增加,缺口环法测试结果与广义缺口环法测试结果的相对偏差逐渐增大;且广义缺口环法测得的石英玻璃弹性模量和弯曲强度值与三点弯曲法的测试结果更接近,即广义缺口环法的测试结果更准确;同时表明了广义缺口环法既适用于薄壁管材的力学性能测试,也适用于厚壁管材的力学性能测试。

Tube is a kind of significant fbrm of material product structure,and the accurate evaluation of the tube mechanical properties is crucially important for insuring the service safety and reliability of the tube components.The presented split ring method provides feasible solution to the determination of tube mechanical properties,but the formulas for calculating the elastic modulus and bending strength apply only to the thin-walled tubes.To determine the mechanical properties of thick-walled tubes accurately,the general split ring method with wider application range was proposed in this study based on the analytical theory for curved bar,by taking into account the effect of the radial and tangential forces on the strain energy of the tube sample.The three-point bending method was used to test the elastic modulus (72.08±1.87 GPa) and bending strength (73.84±6.67 MPa) of the quartz glass beams,and the test result can be used as the reference data.Both the split ring method and general split ring method were used to determine the elastic modulus and bending strength of the same quartz glass tubes.The test results indicate that the relative deviation between the measured data by split ring method and general split ring method gradually increased with the ris ing wall thickness of the tube samples.The elastic modulus and bending strength tested by the general split ring method were closer to the test results by three-point bending method,i.e.,the results measured by the general split ring method were more ac curate.And the general split ring method can be used to determine the mechanical properties for both the thin-walled and thick-walled tubes.