How to predict creep failure/rupture of ABS plastic hook?
In a plastic ABS cantilever hook, I calculated that the bending stress to be 28MPA.
The Proportional Limit for this specific ABS plastic is 45MPA. Flexural/tensile strength= 45MPA
I have creep data test at 18MPA-3,000MPA , 23C, for 10000 hrs.
However, using the creep data, I do not know how to predict if this part will creep rupture.
I know it will because I have proven it in actually testing, but I need to show that analytically we can predict what design will failed without creating parts.
It is half way to the P/L so I cannot use the P/L as the cutoff point.
Is there an equation to calculate if the part will failed due to Creep Rupture?
The modeling approach is a significant improvement over currently available analytical design equations. The model captures the effect of a snap-fit’s catch in causing contact forces to be offset from the beam’s neutral axis. Beam rotation, influence of axial force, and moment components on beam deformation are also incorporated by formulating a set of equations that model the system in its deformed configuration. The equation system is iteratively solved for several such configurations to model insertion and retention processes for snap-fits. The axial force component, which has been hitherto ignored in analytical design equations, is found to have significant effect on predicted snap-fit performance. The design space of cantilever hook features is explored by varying input design parameters. The model shows excellent agreement with experimental results, especially for low and medium retention angle snap-fit features. However, for high retention angle snap-fits, more accurate governing equations are required.
