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Impact fatigue loading - импульсивное нагружение усталостного типа

N 22

SHOCK AND IMPACT PROPERTIES (III)

Characteristics of the structure. The damage produced by shock loading is naturally dependent upon the characteristics of the structure. If the time of application of the load is short compared to the lowest natural frequency of vibration of the structure or machine, an impact load is produced, whereas if the time of load application is long, the load is considered to be static. In most cases, if the time of load application is less than one-half the lowest natural frequency of vibration, the load is definitely considered to be a shock or impact load. If this time interval is greater than three time the natural frequency, the load is generally considered to be a static load. The time of loading referred to above is the time required to increase the load from zero to a maximum value. For dynamic shock loads the shape of the load-time curve, particularly the steepness of its rise or fall is important. The impulse (equal to the area under the load-time curve) is a basic con­sideration in design. On the other hand, for slow loading, the shape of the load-time curve is unimportant since the maximum load is the major design factor.

Notes :

shock loading - ударная нагрузка

Impact loading - импульсивная нагрузка

load-time curve - нагрузочно-временная кривая