I have done the tensile strength test on two kinds of tensile specimens with the same material, but the mechanical behaviors differ from each other.
My considerations are focused on the size effect factor of test specimens, but I don't know how this parameter manipulates the mechanical behavior.
I would be grateful for any suggestions.
There is no single factor for all materials that reflects the influence of sample size on the result of strength measurement. It is quite natural that small specimens often show higher specific strength than large specimens, since statistically they have fewer structural defects. However, this difference in specific strength depends on many properties of the material, primarily on its deformability: the more plastic the material, the smaller the difference.
Dear Vadim Verlotski
Thank you for the contribution, the experiment material is a polymer-metal composite, and the role of added metal in both macro and micro are the same. on the other hand, changing the specimens' size gave us different results. is there any reference for the discussed topic?
With all due respect
Dear Milad Zeynivandnejad,
can you show your test results (stress-strain curves) for micro and macro metal-polymer samples as well as material and sizes of these samples? This give us the opportunity to evaluate the role of leading factor.
Dear Serge V. Shil’ko
I appreciate the contribution. This is the stress-strain result for my reference material, which is PLA. By adding the reinforcement metal to the PLA matrix, their stress-strain curve would give lower strength than the reference material.
P.S: the curve and picture of the sample on the left side are for micro tensile and on the right side is for macro tensile.
Best regards.
Dear Milad Zeynivandnejad,
the preliminary analysis of your results shows that stress - strain curve of "PLA (macro)" is smooth with extensive yield plateau although the ultimate elongation of "PLA (macro)" is the same as for "PLA (micro)". Probably, more localized deformation of "PLA (micro)" sample promotes realization of hardening process but decreasing of load-carrying ability due to micro failures on the flowing part of curve. In turn, this effect may be stipulated by specific geometry of sample "PLA (micro)" and sensitivity of sample quality to 3D printing of small products.
Dear Milad,
Could you say briefly, how the micro-test was performed?
Regards,
Eugeniusz Sajewicz
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