偏心拉杆极值应力的电测法研究

Electrometric method experiment study on extremum stress of eccentric tensile links

基于组合变形理论推导了偏心拉杆危险点的拉、压应力计算公式;利用静态电阻应变仪及材料力学多功能台,采用半桥单臂惠斯通电桥测得了杆件材料的杨氏弹性模量及偏心拉杆的危险点应力;采用半桥双臂及全桥对臂法分别测得了轴向力及弯矩单独作用下的拉应变,并由胡克定律得到了偏心拉伸截面上的最大拉应力及压应力.研究表明,通过电测法所得危险点应力与理论值非常吻合,研究结果证实了方法的可行性.

The formula of calculating tensile and compressive stress of dangerous point on eccentric tensile links is derived based on composite deformation theory.Young's elastic modulus and the stress at the dangerous point are measured by a material mechanics multi-function test-bed and a static resistance strain instrument and by the half bridge-single arm of Wheatstone bridge.The tensile strain under the independent effect of axial force and bending moment is measured respectively by the half bridge-dual arm and full bridge-opposite arm method,then maximum tensile and compressive stress on the section of the tensile eccentric links are obtained by Hooke law.The results show that the stress of the dangerous point by electrometric-method experiment is approximately equal to the theo-retical solution and the research results prove that the experiment method is reliable.