I did an experiment to find ot how the strain in a loaded perspex tensile specimen varied with time.
i loaded the specimen with a 40lb load and then measured the strain every 20 seconds for a five min period. i did not add or remove any more loads during this period. here are my results.
Time (s) Strain
as you can see it tends to increase but for some time it stays constant. do you have any idea why it increases and sometimes stays constant? i need to explain what the cause of this behaviour is.
thanks in advance.