Utjecaj dugotrajne mjerne stabilnosti tvrdomjera na mjernu nesigurnost mjerenja tvrdoće

master's thesis

• Title (english): Influence of the long-term hardness measurement stability on the measurement uncertainty in hardness measurement
• Author: Adriana Jovanović
• Mentor: Željko Alar (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2023-07-20, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Mjerenje tvrdoće je važno u industriji i laboratorijima za pružanje informacija o svojstvima
materijala. Dugotrajna stabilnost tvrdomjera ključna je za osiguravanje točnosti rezultata.
Pogreške u mjerenju mogu nastati zbog trošenja ispitnih tijela, promjena svojstava materijala i
kalibracijskih nesigurnosti. Osim dugotrajne stabilnosti, važno je uzeti u obzir i druge faktore
poput pravilne tehnike mjerenja, kvalitete ispitnih tijela i uvjeta okoline kako bi se osigurala
točnost i pouzdanost mjerenja tvrdoće. U eksperimentalnom dijelu provedeno je umjeravanje
tvrdomjera u kontroliranim uvjetima na Fakultetu strojarstva i brodogradnje. Umjeravanje se
provodilo prema normi ISO 6507-2:2018 koristeći direktnu i indirektnu metodu umjeravanja.
Direktna metoda provjerava sile opterećivanja, sustav za očitanje i veličine otisaka a indirektna
metoda uključuje mjerenje tvrdoće na pet mjernih mjesta preko cijele ispitne površine uz pomoć
etalonskih pločica tvrdoće. Dobiveni rezultati uspoređivani su s onima dobivenih umjeravanjem
istog uređaja u 2014. i 2018. godini te su se analizirale pojave odstupanja u rezultatima
indirektne i direktne metode.

Abstract (english)

Hardness measurement is important in industry and laboratories as it provides information
about material properties. Long-term stability of hardness testers is crucial for ensuring result
accuracy. Variations in results can occur due to wear of test specimens, changes in material
properties, and calibration uncertainties. In addition to long-term stability, other factors such as
proper measurement technique, quality of test specimens, and environmental conditions need
to be considered to ensure accuracy and reliability of hardness measurements. In the
experimental part, calibration of the hardness tester was performed under controlled conditions
at the Faculty of Mechanical Engineering and Naval Architecture. Calibration was conducted
according to the ISO 6507-2:2018 standard, using direct and indirect calibration methods. The
direct method verifies the loading forces, measuring system system, and diagonal of reference
indentation, while the indirect method involves hardness measurements at five measurement
points evenly distributed across the entire test surface using hardness reference blocks. The
obtained results were compared with the calibration results of the same device in 2014 and
2018, and certain deviations in the results of the indirect and direct methods were analyzed.

• Keywords: tvrdoća; sljedivost; Vickers; umjeravanje
• Keywords (english): hardness; measurement stability; Vickers; calibration
• Language: croatian
• URN:NBN: urn:nbn:hr:235:028831
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-07-18 21:16:36