magistrsko delo magistrskega študijskega programa II. stopnje Strojništvo
David Gliha (Author), Tomaž Kek (Mentor), Roman Šturm (Co-mentor)

Abstract

Merjenje trdote z vtiskanjem tršega telesa v površino materiala omogoča določitev ene izmed najbolj pomembnih mehanskih lastnosti materiala. Pri tem lokalno v vzorcu na mestu vtiska nastanejo elastične in plastične deformacije s posledičnim utrjevanjem materiala. Vtiskovanje sferokonične diamantne konice v preizkušani material med merjenjem trdote prav tako omogoča nastanek signalov akustične emisije (AE), ki jih lahko zaznamo s PZT senzorji, pritrjenimi na površino vzorca. Zajem signalov AE med merjenjem trdote omogoča spremljanje odziva materiala na deformacijo. Signali AE so predvsem posledica nastanka in širjenja razpok, drsenja dislokacij in trenja vdiralnega telesa ob površino vzorca. Predstavljena je merilna veriga za zaznavanje signalov AE med merjenjem trdote različno toplotno obdelanih jekel, stekla in keramike. Signali AE so bili zajeti pri različnih obremenitvah vdiralnega telesa. Ugotovljene so odvisnosti med obremenitvenimi pogoji vdiralnega telesa in zaznanimi signali AE. Prikazana je značilna oblika signala pri rasti razpoke v trdih in krhkih materialih.

Keywords

magistrske naloge;akustična emisija;merjenje trdote;signal akustične emisije;razpoka in njena rast;dislokacije;plastična deformacija;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FS - Faculty of Mechanical Engineering
Publisher: [D. Gliha]
UDC: 620.179.17:539.3(043.2)
COBISS: 21418243 Link will open in a new window
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Downloads: 199
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Other data

Secondary language: English
Secondary title: Measuring acoustic emission signals during the indentation test
Secondary abstract: Hardness testing by indenting a loaded object into the material surface allows us to determine one of the most important mechanical properties of the material. Elastic and plastic deformations occur locally in the specimen of the indentation with the consequent of material hardening. The indentation process of a spheroconical diamond indenter into the tested material during the hardness testing also allows the arising of acoustic emission (AE), which could be detected by PZT sensors attached to the sample surface. Capturing the AE signals during the hardness testing allows monitoring of how the material responds to the deformation. The AE signals are mainly the result of the formation and expansion of cracks, sliding of the dislocations, and friction of the indenter against the specimen surface. A measurement chain is presented for the AE signals detection while testing the hardness of different heat-treated steel, glass, and ceramics. AE signals were detected at different loads of the indenter. Dependencies between the loading conditions of the indenter and the detected AE signals were found. A typical signal shape of crack growth in hard and brittle materials is shown.
Secondary keywords: master thesis;acoustic emission;hardness measurement;acoustic emission signal;crack and its growth;dislocations;plastic deformation;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. Ljubljana, Fak. za strojništvo
Pages: XXIV, 58 str.
ID: 11849852
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