This thesis investigates the fracture of nearly incompressible hyperelastic media. It covers the different characteristics of bulk material failure under dilatational or distortional loads and develops a unified description of the corresponding failure surface. It proposes a coupled strain and energy failure criterion for the assessment of notch-induced crack nucleation and presents a weak-interface-model that allows for efficient stress, strain and failure analyses of hyperelastic adhesive lap joints. Theoretical concepts for the measurement of fracture properties of nonlinear elastic materials are provided. The methodology is developed using two exemplary hyperelastic silicones, DOWSIL 993 Structural Glazing Sealant and DOWSIL Transparent Structural Silicone Adhesive, and is validated using large sets of experiments of different loading conditions.
Author(s): Philipp Laurens Rosendahl
Series: Mechanik, Werkstoffe und Konstruktion im Bauwesen, 57
Publisher: Springer Vieweg
Year: 2021
Language: English
Pages: 204
City: Wiesbaden
Preface
Abstract
Kurzfassung
Table of contents
Nomenclature
1 Introduction
1.1 Motivation
1.2 State of the art
1.3 Objectives and structure
2 Theoretical background
2.1 Fundamentals of continuum mechanics
2.1.1 Kinematics
2.1.2 Stress
2.1.3 Balance principles
2.1.4 Hyperelasticity
2.2 Bulk material failure
2.3 Fracture mechanics
2.4 Finite fracture mechanics
3 Samples and finite element models
3.1 Unnotched specimens
3.1.1 Dumbbell specimens
3.1.2 Bulge specimens
3.1.3 Uniaxial compression specimens
3.1.4 Tubular lap shear specimens
3.2 Notched specimens
3.2.1 H-shaped specimens
3.2.2 Notched tubular lap joints
3.2.3 Pancake specimens
3.2.4 Cleavage double cantilever beam specimens
3.2.5 Out-of-plane shear double cantilever beam specimens
4 Experimental material characterization
4.1 State of the art
4.2 Characterization of the constitutive behavior
4.3 Bulk material extensibility
4.4 Fracture toughness
4.4.1 Cleavage tests
4.4.2 Out-of-plane shear tests
5 Bulk material failure
5.1 State of the art
5.2 Generalized deviatoric function
5.3 Equivalent strain failure criterion for hyperelastic media
5.4 Combined distortional–dilatational failure mode concept
6 Nucleation of finite cracks in hyperelastic materials
6.1 State of the art
6.2 Mixed-mode crack nucleation criterion
6.3 Failure prediction
6.3.1 Simple shear test
6.3.2 Pull-off and tubular shear tests
6.3.3 Pancake test
6.3.4 Discussion
6.4 Crack nucleation, crack growth and crack arrest
6.5 Derivation of a simple design tool
7 Hyperelastic weak interface model
7.1 State of the art
7.2 Sandwich-type model for nonlinear elastic adhesives
7.3 Stress and strain analysis
7.4 Failure prediction
8 Conclusions and perspectives
References
