Određivanje parametara konstitutivnog i lomnog ponašanja PBT materijala ojačanog staklenim vlaknima

master's thesis

• Title (english): Determination of constitutive and fracture parameters of PBT material reinforced by glass fibres
• Author: Stipe Grdović
• Mentor: Tomislav Lesičar (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-12-09, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

U današnjem svijetu ispunjenom tehnološki naprednim i modernim vozilima, električni konektori imaju iznimno veliku ulogu pri povezivanju različitih električnih sustava. Među najpoznatijim materijalima za izradu modernih električnih konektora je polibutilen tereftalat (PBT). Jedna od glavnih prednosti mu je relativno jednostavna mogućnost ojačavanja mehaničkih svojstava ovisno o zahtjevima kupca. Varijacija PBT materijala koja će se koristiti u ovom radu je PBT ojačan s 30% staklenih vlakana (PBT-GF30). Tema ovog rada je određivanje i validiranje parametara konstitutivnog i lomnog ponašanja materijala PBT-GF30. Rad je podijeljen u šest poglavlja. U prvom poglavlju dan je kratki uvod i osvrt na temu PBT materijala te javno/internetski dostupnih mehaničkih svojstva vezana za njega. Unutar drugog poglavlja definiran je konstitutivni model ponašanja materijala. Počevši od jednostavnog linearnog elastičnog modela, zatim uzimajući u obzir elasto-plastično ponašanje i na kraju mehaniku oštećenja i loma, razvijen je konstitutivni model ponašanja konstrukcije. Tema ovog rada je ispitivanje krhkog tipa loma, koji se odvija pri malim deformacijama zbog iznimnog nagomilavanja pogrešaka u materijalu u kratkom vremenu. U trećem poglavlju opisano je eksperimentalno ispitivanje testnog uzorka, epruvete, jednoosnim statičkim vlačnim testom. Također, norma prema kojoj su izrađeni testni uzorci i DIC metoda obrade rezultata je obuhvaćena ovim poglavljem. Unutar četvrtog poglavlja materijalni model je validiran numeričkim simulacijama statičkog vlačnog testa korištenjem programskog paketa Abaqus®. Nadalje, peto poglavlje je iskorišteno za primjenu razvijenog materijalnog modela na stvarni problem/konstrukciju. Za primjer je iskorišten TPA osigurač (Terminal position assurance) razvijen unutar tvrtke Yazaki Europe Limited Zagreb (YELZ). Šesto poglavlje je ujedno i zaključno poglavlje. U njemu je dan zaključak i popratni komentari vezani uz kalibraciju ovisno o geometriji problema. Također, dan je prijedlog dodatnog poboljšanja materijalnog modela koji bi uključio lomno ponašanje konstrukcije pri tlačnom i smičnom opterećenju.

Abstract (english)

In today’s world of technologically advanced and modern vehicles, electrical connectors play a critical role in linking various electrical systems. Among the most prominent materials used in the manufacture of modern electrical connectors is polybutylene terephthalate (PBT), valued particularly for its relatively simple adaptability in reinforcing mechanical properties based on customer specifications. The variant of PBT used in this study is reinforced with 30% glass fibers (PBT-GF30). This work focuses on determining and validating the constitutive and fracture behavior parameters of the PBT-GF30 material. The study is organized into six chapters. The first chapter provides a brief introduction to PBT materials and a review of publicly available data regarding their mechanical properties. In the second chapter, the constitutive model of material behavior is defined. Beginning with a basic linear elastic model, it progresses to include elasto-plastic behavior and ultimately damage and fracture mechanics, resulting in a comprehensive constitutive model for structural behavior. This study specifically examines brittle fracture, which occurs at small deformations due to the rapid accumulation of defects within the material over a short period.The third chapter describes the experimental testing of the specimen through a uniaxial static tensile test. Standards for specimen fabrication and the Digital Image Correlation (DIC) method used for data analysis are also discussed here. In the fourth chapter, the material model is validated using numerical simulations of the static tensile test conducted with the Abaqus® software package. The fifth chapter then applies the developed material model to a real-world scenario, with a Terminal Position Assurance (TPA) component developed by Yazaki Europe Limited Zagreb (YELZ) serving as the practical example. The sixth and final chapter presents the conclusion, along with observations related to calibration based on problem geometry. Additionally, a proposal for further improvement of the material model is provided, which would incorporate fracture behavior under compressive and shear loading conditions.

• Keywords: električni konektor; polibutilen tereftalat (PBT); elastoplastičnost; krhki lom; DIC; Abaqus®; metoda konačnih elemenata; TPA
• Keywords (english): electrical connector; polybutylene terephthalate (PBT); elastoplasticity; brittle cracking; DIC; Abaqus®; finite element method; TPA
• Language: croatian
• URN:NBN: urn:nbn:hr:235:394876
• Study programme: Title: Mechanical Engineering; specializations in: Design, Process and Energy Engineering, Production Engineering, Engineering Modelling and Computer Simulation, Marine Engineering, Industrial Engineering and Management, Materials Engineering, Mechanics and Robotics, Autonomous Systems, Mechatronics and Robotics; Course: Engineering Modelling and Computer Simulation; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva (sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2026-11-28
• Created on: 2024-12-05 15:26:22