Stress Concentration Analysis of Materials
Tran, Thi Kim, Lien (2016)
Tran, Thi Kim, Lien
Yrkeshögskolan Arcada
2016
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2016060111227
https://urn.fi/URN:NBN:fi:amk-2016060111227
Tiivistelmä
This thesis work is to study the stress concentration around a circular hole with different radius in a finite width, tensile loaded plate by the experimental methods including tensile testing and photoelasticity, and computational method performed by COMSOL Multiphysics. Holes with diameter of 1, 2, 3, 4, and 5 mm were drilled in the middle of ASTM D638 standard specimens which were prepared by injection moulding technique. Photoelastic techniques were used to observe the available stresses in free of load condition in a series of two-dimensional models. Polyethylene terephthalate was chosen to study due to its high birefringent index.
The stress concentration factor obtained from computational method is 6% greater than that derived from theoretical method. As the ratio of hole diameter over specimen’s width increases from 0 to 0.83, the stress concentration factor decrease from 3 to 2.94 in theoretical method and from 2.71 to 2.16 in computational method. The stress concentration factor is independent from materials made up the element but geometry, notch sensitivity, on the contrary, is material factor which is used to predict the fatigue strength of structural element containing holes. The study shown a result that fatigue strength of material reduces roughly 50% as the diameter of the hole increases by 1 mm in a same width specimen. Experimental fatigue strength shows 30% lower in magnitude compared to theoretical predicted value.
The stress concentration factor obtained from computational method is 6% greater than that derived from theoretical method. As the ratio of hole diameter over specimen’s width increases from 0 to 0.83, the stress concentration factor decrease from 3 to 2.94 in theoretical method and from 2.71 to 2.16 in computational method. The stress concentration factor is independent from materials made up the element but geometry, notch sensitivity, on the contrary, is material factor which is used to predict the fatigue strength of structural element containing holes. The study shown a result that fatigue strength of material reduces roughly 50% as the diameter of the hole increases by 1 mm in a same width specimen. Experimental fatigue strength shows 30% lower in magnitude compared to theoretical predicted value.