输电线路耐张线夹压接长度对其抗拉承载力及失效模式的影响分析

Tension Capacity and Failure Mode of Strain Clamp under Different Clamping Lengths between the Steel Anchor and Steel Core

以NY-300/40压缩型耐张线夹为对象,建立了耐张线夹-导线系统的LS-DYNA三维有限元模型,模拟研究了标准压接长度(110 mm)时耐张线夹的拉伸受力性能并与试验结果进行了对比,验证了模型的正确性,在此基础上分析了钢锚与钢芯压接长度变化时耐张线夹的抗拉承载特点。研究表明,耐张线夹的握力主要来自于钢锚与钢芯的压接。标准压接情况下,耐张线夹的抗拉承载力能满足设计要求,而且由于压接长度足够,其失效方式是铝绞线断裂而非钢芯从钢锚中拉脱。当钢锚与钢芯压接长度不足时,随着压接长度的减小,耐张线夹的握力亦逐渐减小,虽然其握力绝对值减小幅度不大,但其破坏模式逐渐由铝绞线断裂转变为钢芯被从钢锚中拉脱,就本文的分析对象而言,破坏模式发生转变时钢芯与钢锚间的临界压接长度在50~60 mm。

Taking the NY-300/40 compression strain clamp as an example,the three-dimensional finite element model of the strain clamp-conductor system was established by LS-DYNA software.The tensile behavior of the strain clamp with standard clamping length(110 mm)was simulated and compared with the experimental results.On this basis,the tension capacities and failure modes of the strain clamp under different clamping lengths between the steel anchor and the steel core were also analyzed.The results show that the grip strength of the strain clamp mainly comes from the compression between steel anchor and steel core.Under the condition of stan-dard clamping length,the tension bearing capacity of the strain clamp can meet the design requirements.Because the clamping length is enough,the failure mode of tension clamp is the breakage of the aluminum strands rather than the steel core pulled out.When the clamping length between the steel anchor and steel core is insufficient,the grip strength of the strain clamp decreases gradually with the reduction of the clamping length.Although the absolute value of the grip strength decreases slightly,the failure mode of the tension clamp gradually changes from the mode of the aluminum strands breaking to the mode of the steel core being pulled off from the steel anchor.The corresponding clamping length between the steel core and the steel anchor of the mentioned strain clamp is between 50 mm and 60 mm,when the failure mode shifts from one to another.