Finite element analysis has dominated the world of computational structural mechanics for the past half century, however, since seminal work by Demirdžic et al. [1] finite volume stress (FV) analysis has become a viable alternative. The apparently simple problem of a body undergoing large rotation is far from trivial when considered numerically. This research develops a large strain FV structural solver that accurately calculates the large rotation of solid bodies with particular attention paid to non-orthogonal meshes and mesh movement.

The exposure of the human thorax to high external loads can cause severe injuries to internal organs, particularly to lungs, and can be fatal in many instances. The most critical are rapidly changing loads caused by impacts and blasts, resulting from car crashes, collisions and explosions. This work is focused on the development of a surrogate lung material that not only reproduces the dynamic response of a human lung under various loading conditions but also allows the analysis of the extent and distribution of damage, thus potentially eliminating the practice of live animal testing. The surrogate material consists of polyurethane foam and fluid‐filled gelatin microcapsules. In order to characterize surrogate material, various tests were conducted on microcapsules and surrogate material itself. Initially, the bursting pressure of the microcapsules was investigated using low and high rate compression tests. A bursting pressure of around 5 bar was obtained which is comparable to the reported lung overpressure at injury level. Furthermore, low and high rate compression tests were conducted on the surrogate lung specimens to obtain the stress wave speed in the material. The wave speed was found to be well in the range of the reported values for both animal and human lungs (16‐70 m/s). A CT scan analysis was carried out before and after the impact tests to study the damage. The damage analysis was then compared to the Bowen curves. Excellent agreement was obtained.

35th Annual Meeting of the Adhesion Society, New Orleans, Louisiana, 26 to 29 February, 2012

This work is conducted as a part of a wider international activity on mixed mode fractures in beam-like geometries under the coordination of European Structural Integrity Society, Technical Committee 4. In its initial phase, it considers asymmetric double cantilever beam geometry made of a linear elastic material with varying lower arm thickness and constant bending moment applied to the upper arm of the beam. A number of relevant analytical solutions are reviewed including classical Hutchinson and Suo local and Williams global partitioning solutions. Some more recent attempts by Williams, and Wang and Harvey to reproduce local partitioning results by averaging global solutions are also presented. Numerical simulations are conducted using Abaqus package. Mode-mixity is calculated by employing virtual crack closure technique and interaction domain integral. Both approaches gave similar results and close to the Hutchinson and Suo. This is expected as in this initial phase numerical results are based on local partitioning in an elastic material which does not allow for any damage development in front of the crack tip.

In this study the adhesive joint fracture behaviour of a nano-toughened epoxy adhesive was investigated. Two experimental test methods were used; (i) the standard tapered double cantilever beam (TDCB) test to measure the mode I adhesive joint fracture energy, GIC, as a function of bond gap thickness and (ii) a circumferentially deep notched tensile test to determine the cohesive strength of the adhesive for a range of constraint levels. It was found that the fracture energy of the adhesive followed the well-known bond gap thickness dependency [1]. SEM analysis of the TDCB fracture surfaces revealed significant plastic void growth. Finally, numerical modelling of the experimental tests suggested that most of the fracture energy was dissipated via highly localised plasticity in the fracture process zone ahead of the crack tip.

In the present study, the mixed-mode fracture toughness of an adhesively bonded composite joint system was examined using a variety of linear elastic fracture mechanics (LEFM) based tests. These tests include the mode I double cantilever beam (DCB), mixed-mode asymmetrical DCB (ADCB) and mode II end load split (ELS) test. The joint system was also evaluated using the wide area lap shear (WALS) test that is often employed by the aerospace industry. While lap shear type tests are relatively simple to perform and post-process compared to their LEFM counterparts, the results can often be misleading and are greatly dependent on the overlap length, thickness of substrate and type of fillet. The experimental tests were also simulated using OpenFOAM, a finite volume based software package. Through this combined experimental-numerical approach, a greater understanding of the influence of the peel ply surface treatment and scrim cloth on the behaviour of the WALS test was achieved.

Plastic containers are extensively used for transportation and storage of a vast variety of fluids due to their low production cost and easy manufacturing. Nevertheless, they are prone to sudden failure when subjected to impact loading, such as drop impact. There is a basic lack of understanding of the fundamental mechanisms leading to such failure as well as the effects of parameters, such as pressure, strain rate, container design, material properties, etc.. The main aim of this study is to investigate the behaviour of water-filled blow-moulded polyethylene containers sunbjected to drop impact, and the mechanisms leading to their failure in order to be able to predict when such failure will occur. To this end, a combined experimental-numerical investigation is applied. Standard and instrumented drop impact tests are carried out, in parallel with extensive numerical simulations performed using finite-volume based fluid-structure-fracture interaction procedures. This study can be very useful in design of plastic containers as well as to all researchers dealing with various fluid-structure-fracture interaction problems.

Signi cant toughening of structural adhesives is attainable with addition of nano particles.Experimental Tapered Double Cantilever Beam (TDCB) tests conducted at University Col-lege Dublin (UCD) have observed a signi cant dependance of the fracture toughness of theseadhesives with bond gap thickness[2]. Classical analysis suggests the change in toughness maybe attributed to a physical constraint of the size of which a plastic zone around a crack tipmay develop. However, simulation of these TDCB tests using OpenFOAM have found thatlittle plasticity develops in the bulk adhesive layer and is instead concentrated in the fractureprocess zone. Signi cant changes in void evolution with bond gap is observed on the fracturesurface of these tests using SEM. This research aims to develop a realistic numerical model ofthe studied adhesive to investigate the parameters a ecting damage evolution and fracture inthe fracture process zone, which ultimately a ect the toughness of these adhesives.

6th International Conference on Fracture of Polymers, Composites and Adhesives, September 11-15, 2011, Les Diablerets, Switzerland

Title Transferability of Adhesive Fracture Toughness Measurements between Peel and TDCB Test Methods for a Nano-Toughened Epoxy Authors(s) McAuliffe, David; Karac, Aleksandar; Murphy, Neal; et al. Publication date 2011 Conference details 34th Annual Meeting of The Adhesion Society, Inc. Savannah, GA, USA, February 13-16, 2011 Publisher Adhesion Society Item record/more information http://hdl.handle.net/10197/4765