An Experimental and Numerical Study of Deformation and Decohesion Mechanisms During Peel Testing of a Laminate Packaging Material

• The material used in packages for the food and dairy industries comprise multiple laminate layers, each serving different purposes in preserving and protecting the package content and by providing the appropriate packagerigidity during handling. Already during package manufacturing and filling, the package material is subject to large deformations and a range of thermal and chemical processes that sometimes cause delamination between thelaminate layers. This, in turn, can lead to a reduced product shelf lifetime and unsatisfactory package performance.In addition, controlled delamination can also be a required material property, for example in the case of package folding or opening mechanisms. Aspects like these emphasize a great need for increased understanding ofadhesion and for the ability to predict adhesion properties of different packaging materials and under different handling conditions. In order to quantify the delamination strength, more or less standardized peel tests are oftenemployed. In such tests, a laminate layer is partly separated to provide the peel arm which is pulled off from the substrate layer(s) at a constant angle. The required peel force is measured along with the peel arm deformationand provides a measure of the delamination strength of the laminate package material. However, the measured force is not only the force component required to separate the layers, but it is also due to deformation of the peelarm and possibly also additional deformation mechanisms in the substrate layer(s). Therefore, not only the cohesive bond between individual laminate layers, but also the properties of the individual laminate layers themselves must be properly characterized. In the present work, peel test experiments have been conducted and the peel force and displacement as well as the peel arm geometry have been monitored. The same peel test has also been studied by numerical simulations using a cohesive zone modeling framework. The influence of thecohesive model formulation and the choice of constitutive model for the peel arm material are investigated in relation to the experimental observations and different delamination mechanisms are observed.

• The material used in packages for the food and dairy industries comprise multiple laminate layers, each servingdifferent purposes in preserving and protecting the package content and by providing the appropriate packagerigidity during handling. Already during package manufacturing and filling, the package material is subject to largedeformations and a range of thermal and chemical processes that sometimes cause delamination between thelaminate layers. This, in turn, can lead to a reduced product shelf lifetime and unsatisfactory package performance.In addition, controlled delamination can also be a required material property, for example in the case of packagefolding or opening mechanisms. Aspects like these emphasize a great need for increased understanding ofadhesion and for the ability to predict adhesion properties of different packaging materials and under differenthandling conditions. In order to quantify the delamination strength, more or less standardized peel tests are oftenemployed. In such tests, a laminate layer is partly separated to provide the peel arm which is pulled off from thesubstrate layer(s) at a constant angle. The required peel force is measured along with the peel arm deformationand provides a measure of the delamination strength of the laminate package material. However, the measuredforce is not only the force component required to separate the layers, but it is also due to deformation of the peelarm and possibly also additional deformation mechanisms in the substrate layer(s). Therefore, not only thecohesive bond between individual laminate layers, but also the properties of the individual laminate layersthemselves must be properly characterized. In the present work, peel test experiments have been conducted andthe peel force and displacement as well as the peel arm geometry have been monitored. The same peel test hasalso been studied by numerical simulations using a cohesive zone modeling framework. The influence of thecohesive model formulation and the choice of constitutive model for the peel arm material are investigated inrelation to the experimental observations and different delamination mechanisms are observed.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Teknisk mekanik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Applied Mechanics (hsv//eng)

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