Studies show that the formation of stable electrical contact between a graphite cylinder and a copper electrode is essential for generating a stable heat source in penetration brazing of heating cables. In this regard, a novel numerical approach is developed to investigate the contact mechanics. In this regard, the fractal theory is applied to analyze the effect of different materials and geometrical properties on the contact parameters and obtain an appropriate contact model for the electrical contact resistance. Then the proposed mathematical model is validated through the experiment. Moreover, the heat diffusion process is analyzed. The pre-scale film is used in the experiment to record the contact area between the graphite cylinder and the copper electrode. Obtained results show that the common graphite cylinder is the best candidate to ensure a stable heat source for heating the cable welding. It is found that obtained results from the proposed model have excellent agreement with the experiment. Accordingly, it is concluded that the proposed model is capable of accurately predicting the dynamic characteristics of the contact between the graphite cylinder and the copper electrode in the welding cores of heating cables.

研究表明，石墨圆柱体和铜电极之间形成稳定的电接触对于在加热电缆的穿透钎焊中产生稳定的热源至关重要。在这方面，开发了一种新颖的数值方法来研究接触力学。对此，应用分形理论来分析不同材料和几何特性对接触参数的影响，并获得合适的接触电阻模型。然后通过实验验证所提出的数学模型。此外，分析了热扩散过程。实验中使用预刻度膜记录石墨圆柱体与铜电极的接触面积。结果表明，普通石墨圆柱体是保证电缆焊接加热稳定热源的最佳选择。发现从所提出的模型中获得的结果与实验非常吻合。据此得出结论，该模型能够准确预测发热电缆焊芯中石墨圆柱体与铜电极接触的动态特性。