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Fracture Mechanical Trouser Taer Testing of thin polymer films
Blekinge Institute of Technology, School of Engineering.
Blekinge Institute of Technology, School of Engineering.
Blekinge Institute of Technology, School of Engineering.
2012 (English)Independent thesis Advanced level (degree of Master (Two Years))Student thesisAlternative title
Fracture Mechanical Trouser Testing of thin polymer films (Swedish)
Abstract [en]

Tensile and Trouser tear tests of thin packaging polymer films have been done successfully in this research thesis. Two different polymers (PP and LDPE) are used. Mode I and Mode III fracture tests have been used for crack propagation analysis. Several experiments are performed to calculate the material parameters. The research study includes the experimental test along with virtual tests using the FEM software Abaqus 6.12-1. ASTM standard 1938-08 is followed for specimen size and experiments are performed on Instron 5655 with 100 N load cell, Tetra Pak Package Lab at Lund. Repeatable and reproducible results are obtained for the principle directions (MD, CD and 45) for Tensile and Trouser Test for brittle and ductile film. Experimental and Numerical Tensile tests have been performed and validated on different crack shapes using MTS machine, BTH Material lab. Visual analysis is made using the Scanning Electron Microscope and polarized light microscope to analyze material and crack propagation behavior. Tearing force for crack propagation is extremely small compared to the Tensile tests. A detailed Essential Work of Fracture (EWF) study has also been made to further understand the behavior. The work will provide an aid to simulate the working conditions better to have a detailed understanding of the polymer behavior. Key Words: PP, Mode I , Mode III, Tensile test, ABAQUS simulation, Crack shapes, Tearing behavior, EWF, Polarized light, SEM microscope.

Abstract [sv]

Fracture Mechanical(Numerical and experimental) Trouser Tear Testing of thin polymer films has been performed in this research work. This work is done at Tetra Pak,Lund Sweden in cooperation with Blekinge Institute of Technology,Karlskrona,Sweden. This work has been done in order to gain a better knowledge about the material characterization of thin polymer films used in packaging industry.The work include experimental test,test method development,simulations,advanced technical calculation utilizing finite element method,python script programming,result evaluation and scanning electron microscope (SEM) analysis. Two different types of polymer films were investigated in this work. One oriented polypropylene film (PP) and one low density polyethylene (LDPE) film were experimentally tested. The two thin polymer films can be classified as one low-extensible and one highly extensible material.A brittle-like behaviour in the fracture mechanical testing was showed in the polypropylene film while the low density polyethylene is presenting a highly ductile behaviour. Experimental tensile testing in various loading conditions,crack shapes and fracture modes has been performed using ASTM standard methods like ASTM D1938-08, ASTM D624 and ISO 6383-1. Experimental Test procedure was significantly improved and repeatable results were obtained. Accurate and reliable measurements were accomplished. Utilized and developed Python scripting for extraction of the experimental data and simulation results for post processing,analyzing and finally visualization in graphs. Material model parameters were calibrated for continuum and damage material modelling of the thin polymer films used in package material structure.Experimantal Trouser tear test was simulated successfully in FEM modelling and analysis software Abaqus 6.12-1 using the calibrated material data. Very accurate and converging numerical and experimental results for tesnile test cases and trosuer tear testing are obtained and compared. Experimental and numerical results find a very close match with each other. Finally scanning electron microscope (SEM) crack tip analysis is also performed to define and show the anisotropy in the thin polymer films. Ductile and brittle material behaviour of slighly extensible and highly extensible polymer films is also shown using SEM microscopic graphs. Video result links of all these tests are also provided.

Place, publisher, year, edition, pages
2012. , 76 p.
Keyword [en]
Key Words: PP, Mode I , Mode III, Tensile test, ABAQUS simulation, Crack shapes, Tearing behavior, EWF, Polarized light, SEM microscope.
National Category
Mechanical Engineering
URN: urn:nbn:se:bth-4228Local ID: diva2:831557
0760609695(Nasir Mehmood)Available from: 2015-04-22 Created: 2012-11-10 Last updated: 2015-06-30Bibliographically approved

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