Premium
A comparison of constant and complex creep loading programs for several thermoplastics
Author(s) -
Benham P. P.,
Hutchinson S. J.
Publication year - 1971
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760110411
Subject(s) - creep , materials science , stress relaxation , composite material , compression (physics) , tension (geology) , dwell time , softening , stress (linguistics) , polypropylene , medicine , clinical psychology , linguistics , philosophy
Polymethyl methacrylate, polyacetal and polypropylene samples were subjected to constant‐load uniaxial creep in tension and compression up to 3% strain in times up to 10 5 sec. A higher creep resistance was obtained in compression compared with tension due to the influence of free volume on mobility. Square wave cyclic creep tests alternately in tension and equal compression for dwell times of 10, 100, 1000 sec were also conducted on each material up to a total time of 10 5 sec. Under low cyclic creep stresses tension creep cancelled out compression creep in each successive half cycle so that there was no overall increase in creep strain as cycling proceeded. The unidirectional creep data was used successfully to predict this behavior. At higher cyclic stress levels creep strain range increased steadily throughout the test indicating a softening process. A few tests were conducted in unidirectional and cyclic stress relaxation on polymethyl methacrylate.