OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 3 2023 a b Fig. 10. Relation between rigidity and relative strength of welded joints: a – steel 45 + steel 45; b – steel 45 + steel R6M5 above. These methods are based on the premise considering lack of welding penetration as a mechanical contact between two solid bodies, which possesses enhanced damping properties. It is proposed to control connections by the static hysteresis loop method. The characteristics for evaluating the strength of welded joints are absorption coefficient, energy dissipation and rigidity of joints with a static method of control. The amplitude dependences of the characteristics under consideration are built for a batch of joints welded in different modes according to this method. Then, the destruction of joints is carried out. Further, the correspondence of each curve to the amplitude dependence of certain strength is established. Based on these data, the dependence graphs of the absorption coefficient, energy dissipation or rigidity of the joint strength for certain torque amplitudes are built (Fig. 6, 7, 8). These dependencies are the main calibration charts for determining the joint strength. Knowing the energy dissipation or the absorption coefficient or rigidity of joints at certain loading amplitude, one can determine its strength. The choice of controlled joint characteristics depends on the specific conditions. If it is impossible to maintain exactly the distance between the sensor blades, then it is better to evaluate the strength by the absorption coefficient, which does not depend on the gauge length. If the loading amplitude is not clearly fixed, it is better to determine the strength of joints by its rigidity. Besides, the rigidity of the joints changes if there are pores, which reduce the cross section, while the absorption coefficient practically does not change. The control of joints in terms of energy dissipation, absorption coefficient and its rigidity is associated with large labor intensity in processing experimental data. Labor intensity can be reduced if the energy dissipation is estimated according to the width of the hysteresis loop (fig. 11). Fig. 11. Mechanical hysteresis loops for specimens with different strengths
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