Hardness measurement using load-penetration curve for Brinell indenter

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Hardness measurement using load-penetration curve for Brinell indenter

ارائه دهنده: Provider: Asma Samavati

اساتید راهنما: Supervisors: AH. Mahmoudi (Ph.D.)

اساتید مشاور: Advisory Professors: MH. Mirsadeqi

اساتید ممتحن یا داور: Examining professors or referees: GH.Majzoobi (Ph.D.) F.Freshteh-Saniee (Ph.D.)

زمان و تاریخ ارائه: Time and date of presentation: March 9th 2021-16:00

مکان ارائه: Place of presentation:

چکیده: Abstract: Hardness as an important parameter which correlates well with mechanical properties, is defined as material resistance while another object penetrates. Hardness tests are implemented widely and comprise a large group of forms and scales. By further development in testing equipment and other technologies, recording a history of load-displacement during penetration has become possible. This test which is known as instrumented indentation test attracted lots of attentions all over the world. Lots of researches concentrated in this test for extracting material properties or stress-strain curve. This non-destructive, easy to implement test has ability to be used for in-service applications. Improvement of portable devices for instrumented indentation made it more popular. One important parameter which has studied widely is area of imprint. As there is relationship between this parameter and stress-strain curve, measuring imprint area with acceptable accuracy kindles enthusiasm in researchers to develop this field more and more. One error source which should be considered is deformation around the imprint area. Pile-up and sink-in are two deformation mode. In the first one the material moves upward vertically and in the second one the direction of movement is downward. Due to experimental and numerical studies pile-up and sink-in neglecting may lead to up to %60 error in measuring material properties. Due to importance of these deformation, in this study a new procedure for measuring hardness is suggested. In this procedure there will be no need to observe imprint area and another shortcut is considered to measure hardness. Load-penetration depth is an output of instrumented indentation test and here it is used to extract hardness without optical instruments. Parameters of this curve are extracted and conducted toward prediction of pile-up using artificial neural network tool. In this study the amount of hardness is modified significantly and the need to investigate the imprint area is omitted which is a remarkable achievement toward better measures of mechanical properties. Key word:Hardness-Instrimented indentation-Finite element analysis-Residual stress

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