Spring failure

Figure 10-5. Identification marks on body coils could lead to spring failure...

Figure 10-7. End caps welded to spring. Failure occuired at weld.

Actuator spring failure FaiFDanger Partial valve stroke test ... 

Failed valve due to internal spring failure from excessive wear... 

The interlocking element (limit switch) can fail-to-danger as a result of spring failure or stem-bearing seizure. 

Nesvijski, E.G., Nogin, S.I. Acoustic Emission Technics for Nondestructive Evaluation of Stress of Concrete and Reinforced Concrete Structures and Materials. Third Conference on Nondestructive Evaluation of Civil Structures and Materials, Boulder, CO, 1996. Nesvijski, E. G. Failure Forecast and the Acoustic Emission Silence Effect in Concrete. ASNT s Spring Conference, Houston, TX, 1997. 

In order to ensure virtually failure-free operation, a pohcy of changing this spring at 50,000 cycles of operation might be adopted. 

Stress Relaxation. Copper alloys are used extensively in appHcations where they are subjected to moderately elevated temperatures while under load. An important example is the spring member for contacts in electrical and electronic coimectors. Critical to rehable performance is the maintenance of adequate contact force, or stabiUty, while in service. Excessive decrease in this force to below a minimum threshold value because of losses in spring property can lead to premature open-circuit failure (see Electrical connectors). 

One of the principal reasons for failure due to reaction with the service environment is the relatively complex nature of the reactions involved. Y"et, in spite of all the complex corrosion jargon, whether a metal corrodes depends on the simple elec trochemical cell set up by the environment. This might give the erroneous impression that it is possible to calculate such things as the corrosion rate of a car fender in the spring mush of salted city streets. Dr. M. Pourbaix has done some excellent work in the application of thermodynamics to corrosion, but this cannot yet be applied direc tly to the average complex situation. 

It is this that we wish to maximise. The spring will be damaged if the stress o exceeds the yield stress or failure stress 0, the constraint is ct < Uy. So the maximum energy density is... 

Spring to separate units fail. Failure to separate halves High Use multiple springs. 

Most of the forcing functions generated by V-belt drives can be attributed to the elastic or mbber band effect of the belt material. This elasticity is needed to provide the traction required transmitting power from the drive sheave (i.e., pulley) to the driven sheave. Elasticity causes belts to act like springs, increasing vibration in the direction of belt wrap, but damping it in the opposite direction. As a result, belt elasticity tends to accelerate wear and the failure rate of both the driver and driven unit. 

This phenomenon is attributed to the absence on the end surfaces of the shear and compressive stresses that are needed in order to maintain a state of simple shear. As a result, the stresses throughout the block are affected (in contrast to a conventional end effect that would have a negligible effect far from the ends). One consequence is that high internal stresses can develop, sufficient in principle to cause failure. It is clear that the effect of the special conditions obtaining at the ends should be taken into consideration in the rational design of rubber springs. 

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