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2 2009

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Technique of designing of releasable threaded connections of autotractor technics

Kuzmin A., Shevchuk V.

Journal of KONES

2009

Vol. 16, No. 1

297-306

The analysis of work of joints of tractors of models DT-YT allows to make the conclusion about presence of breakages because of low constructive strength and not correct definition of parameters of details. Probes of breakages of joints shows that today at designing of joints there is no system of the account of a mode of behavior and joint life cycle. Designing of threaded connections of automobile and tractor technics should be carried out taking into account modes and duration of operation of the car on these modes. Designing of threaded connections is carried out taking into account operation and life cycle modes. It is offered to carry out calculation taking into account accumulation of fatigue damages to a current of set time of operation. For definition of parameters of fatigue strength the technique of the accelerated tests is offered. The technique allows to define parameters of fatigue strength which it is necessary to use in calculations threaded connections. In work probes of a tension of joint of a driving wheel of a Caterpillar, are resulted by a method of the is finitely-element analysis. For probes settlement models are offered and tested. Settlement models allow to simplify construction of geometrical model for use in computer programs and calculations. Using the described technique of designing it is developed construction a retainer screw with a special thread.

Fatigue damage cumulation in brass under variable loading

Mroziński S., Dymski S.

Archives of Foundry Engineering

2009

Vol. 9, iss. 3

275-280

In the paper there was presented the course of fatigue damage cumulation in specimens made of CuZn37 brass. During the analysis the course of damage cumulation there were used parameters of hysteresis loop and microstructure changes for different levels of fatigue damage, that were registered during the tests. Basing on the analysis of three hysteresis loop parameters (stress amplitude [...], plastic strain amplitude [...] and plastic strain energy \deltaWpl) it has been found that during variable loading the smallest changes are observed for the energy \deltaWpl. Microscopic analysis of brass specimens after various fatigue levels showed that fatigue damage cumulation is also visible in changes taking place both within grains and at their boundaries. These changes include the presence of failures at boundaries of grains and slide banding systems inside of them, which are typical for plastic strain of the material.