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Properties of thermo-visco-elastic material 42-809 for manufacturing of vibrodamping elements – 3.part
Svoboda, Jaroslav ; Pešek, Luděk ; Frölich, V. ; Klášterka, Petr
In the report the results of rubber elements properties made of thermo-visco-elastic material 42-809 at low temperatures are summariesed. The tests were performed by a loading fatigue machine INSTRON 8502 in a climate chamber. For improving an accuracy of measurement the test machine was equipped with a lesser force transduser Rumburk with a range up to 40kN. The report includes results of static and dynamic characteristics in temperature range 0 ÷ -50°C, measurement of residual deformations, relaxation time and evaluation of a cyclic loading influence to shapes of static characteristics of the rubber. Furthermore the results of rubber element life time and evaluation of friction behaviour at lower temperatures are presented. The limit lines for 10% of residual deformations are drawn here, too.
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Fatigue strength and life of real structures under combined random loading
Svoboda, Jaroslav ; Balda, Miroslav ; Fröhlich, Vladislav
A rather often kind of combined stress is a case, when one of its components acts statically. The contribution deals with some rsults of research works,the goal of which has been to reveal an influence of the static component on a resulting fatigue life, and to find a way of its including into fatigue strength evalutions. A procedure for finding a critical stress for an estimating of a structure save life is presented. Unfortunately, the fatigue life calculation is more complicated and needs some experiments, which will yield additional informstion on a material behaviour under required stress combination and levels.
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