CREEP AND FATIGUE ENDURANCE GUIDELINES
HERE ARE SOME GUIDELINES TO FOLLOW:
RULES ABOUT CREEP -
- Increasing the load on a molded part increases the creep rate.
- Increasing the level of reinforcement in a composite increases
its resistance to creep.
- Particulate fillers provide better creep resistance than unfilled
resins but are less effective than fiber reinforcements.
- Glass fiber reinforced amorphous resins generally have greater
creep resistance than glass fiber crystalline resins containing
the same amount of glass.
- Carbon fiber reinforcement is more effective in resisting creep
than glass fiber reinforcement.
- Flame retardant additives affect different resins in different
ways; each case should be evaluated separately.
- The effect of a flame retardant additive on flexural modulus provides
an indication of its effect on long term creep.
RULES ABOUT FATIGUE ENDURANCE -
- Fiber reinforcements provide significant improvement in fatigue
life of a resin; carbon fibers improve this property more than
glass fibers do.
- Effects of moisture in a service environment on fatigue endurance
should be considered when hygroscopic materials such as nylon
- For service involving a large number of fatigue cycles, crystalline
resins offer more predictable results than amorphous resins because
crystalline materials usually have a definite fatigue endurance
- For optimum fatigue life in service involving both high stress
and fatigue loading, reinforced high temperature resins are recommended.
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INC. M. LODICO -editor