The impact of the internal welding defects on the joint strength

The paper looks at the impact of the internal welding defects on the strength of joints. The tension tests provided the values of the welded joint strength limits depending on the area of sporadic voids, slag intrusions and the field of discontinuities. Considering the results of the conducted experiments, the mathematical relationships between the strength of the welded joint and defected area were concluded. In presence of all three defects, the distance of the defects from the weld surface was measured. It is deduced that the defects nearer to the surface reduce the strength of the welded joint more than those noticed in deeper layers

Ultragarsu suvirintų varinių jungčių stiprumo tyrimas

The results of tensile test of ultrasonically welded connections of copper wires are presented in this article. The connections differ by the number o wires in the connection and also by the combination of wires number at the different sides of connection. The dependence of tensile test results on surface preparation of the wires is settled. When the wires are cleaned from the insulation only mechanically small fibers of insulation remain on the surface of the wires. Those fibers reduce connection strength. Additional cleaning of the wires by compressed air before welding increases the strength of connection up to 35 %. The influence of additional cleaning is especially obvious for connections with large number of wires. The analysis of experimental results is done and the dependence of fracture force on the ratio of perimeter / welded connection area is derived. With reference to the results of tensile tests the suggestion for quality development of ultrasonic welding of copper wires is proposed

Metalų mechaninių savybių kitimo priklausomai nuo eksploatacijos trukmės tyrimas

A long-term operating influence on mechanical properties variation of constructional materials is analysed in this article. During the exploitation of structures and pipelines the consistent surrounding influence causes corrosion of the structures materials. Beside the surrounding influence of the constant stress state affects structures too. For constant stresses mechanical properties of structural elements are variable and the metal is ageing. The article presents experimental researches of hot-water pipelines material. From 20 - 40 years exploited pipelines specimens were cut and tension test was fulfilled. The test results disclosed that material strength stress increased minutely. The value of materials yield stress in exploited specimens showed up later if compared with new material. In the best way the changed materials plasticity properties were exposed by specimens relative elongation, which characterizes materials fragility. Linear materials mechanical properties dependenty on lifetime is presented in the article. According to this linear law it is possible to calculate materials mechanical properties of a structure, which is exploited, and assess safety of this structure

Metalų mechaninių savybių kitimo priklausomai nuo eksploatacijos trukmės tyrimas

A long-term operating influence on mechanical properties variation of constructional materials is analysed in this article. During the exploitation of structures and pipelines the consistent surrounding influence causes corrosion of the structures materials. Beside the surrounding influence of the constant stress state affects structures too. For constant stresses mechanical properties of structural elements are variable and the metal is ageing. The article presents experimental researches of hot-water pipelines material. From 20 - 40 years exploited pipelines specimens were cut and tension test was fulfilled. The test results disclosed that material strength stress increased minutely. The value of materials yield stress in exploited specimens showed up later if compared with new material. In the best way the changed materials plasticity properties were exposed by specimens relative elongation, which characterizes materials fragility. Linear materials mechanical properties dependenty on lifetime is presented in the article. According to this linear law it is possible to calculate materials mechanical properties of a structure, which is exploited, and assess safety of this structure