Fifth International Conference on Engineering Failure Analysis, 1-4 July 2012, Hilton Hotel, The Hague, The Netherlands

To register, go to http://www.icefaconference.com

Embossing of polymeric films destined for usage in the personal care marketplace is an industrial process that produces a very fine pattern, barely discernible to the naked eye, yet has a significant influence on some market-driven properties; more bulk, a soft and smooth touch, reduced crinkling noise and lower gloss. However this comes at a cost to the mechanical properties such as stiffness and ultimate strength capability. Since the feature size of the embossing pattern is so small, it is difficult to obtain all the information from an experiment alone, making the Finite Element Method an ideal analytical tool to help gain additional insight into the effects of some of the design and process parameters. The paper discusses the computational approach, presents results of simulations performed in Abaqus/Explicit for an example 16 micron film and compares to experimentally measured values.

When computer generated imagery (CGI) first started to appear on movie and video
game screens, the emphasis was to make something look close enough to its real counterpart to satisfy audiences. As graphics and computing capability progressed, audiences became less satisfied with “cartoon-like” animation; they demanded more realistic visuals. The entertainment industry reached across the aisle to the scientific community in attempt to incorporate more physical realism into animations. As a result, today’s physics- based CGI can fool even a scrutinizing scientist into believing what he’s seeing is real. While the entertainment industry profited by collaborating with the scientific community, the benefit is mutual. For example, in order to study the fit performance of a dust mask with facial movement, we borrow a CGI technique to make simulation feasible. Specifically, the complex and intricate movements of the face are represented using a high resolution motion capture technique. Similarity between motion capture and finite element data forms allows their interchangeability. In this study, detailed motion capture data of real facial movement was interpreted to produce a finite element model (node and element definitions) along with a time history of nodal displacements. The finite element data was stored as an Abaqus output database and subsequently used as a global model to drive a similar facial submodel to evaluate the fit and sealing performance of a pouch style face mask design under realistic use conditions. This paper outlines the analysis approach and shows results from the simulation.

ABAQUS is used to simulate interactions of an absorbent personal care product (a diaper), with its user and their environment. This problem, being almost completely driven by complex contact between highly deformable and moving bodies, is a challenging proposition. Advanced contact algorithms, non-linear material models and multi-body dynamic analysis capabilities in ABAQUS are used to successfully study the structural interactions of a diaper, a baby and their environment. Aspects of product fit and comfort are often difficult to quantify either by direct measurement or from user feedback. However, by utilizing features of ABAQUS, it is possible to predict physical interactions that occur between the diaper and baby. ABAQUS provides predictions of contact interactions, stress profiles, and strain distributions that are otherwise not measurable. Based on these predictions, one can infer aspects of fit quality and comfort. Detailed predictions of stress, strain and contact within a product also provide a means to evaluate how well that product will be able to perform its intended function. Intimate absorbent personal care products, such as diapers, rely on a combination of containment, redistribution and capture of body waste to provide utility. The function of a diaper is dramatically affected and often driven by structural interactions between itself, its user and the surrounding environment. ABAQUS provides a means to study the response of a complex, multi-component diaper worn by a moving baby.

Origami is the art of paper folding. Our entire range of packages is formed from a flat web of packaging material using the origami technique. Virtual and reverse engineering are fundamental for the development of our technology. Complex simulations like extremely nonlinear dynamic events as well as design optimization are part of our daily activity. This paper describes how Simulia’s software with the help of automated tools has been successfully used to simulate the fundamental phases of our forming process driving in some cases its design.

A finite element (FE) model of the human foot and ankle was developed from 3D
reconstruction of 2 mm coronal MR images from the right foot of a normal male subject using the segmentation software, Mimics. Solid models of 28 foot bones and encapsulated soft tissue structures models established in Solidworks software were imported into ABAQUS for creating the tetrahedral FE meshes. The plantar fascia and 72 ligaments were defined by connecting the corresponding attachment points on the bones using tension-only truss elements. Contact interactions among the major joints were prescribed to allow relative bone movements. A foot support was used to establish the frictional contact interaction between the foot-support interfaces. The contour of the arch-supporting foot orthoses was obtained from digitization of the subject’s foot via a 3D laser scanner. Algorithms were established in Matlab software to create surface models from the digitized foot surface. Solid model of the foot orthoses established in the Solidworks software was properly partitioned in ABAQUS for creating the hexahedral FE meshes. The encapsulated soft tissue and orthotic material were defined as hyperelastic while other tissues were idealized as homogeneous, isotropic and linearly elastic. The ground reaction and extrinsic muscles forces for simulating the stance phase of gait were applied at the inferior ground support and at their corresponding points of insertion by defining contraction forces via axial connector elements, respectively. The FE predictions are being validated by experimental measurements conducted on cadavers and on the same subject who volunteered for the MR scanning.

People are less likely to wear hearing protection that is uncomfortable. The overall comfort of the hearing protection is therefore a primary design feature. Methods for evaluating comfort typically include production and use testing of physical prototypes which are expensive and time consuming which reduces the number of design options to test. This work demonstrates the use of computer modeling to predict wearer discomfort by modeling the interaction between ear protection devices and the human ear.
Obtaining an optimal comfort design is challenging because of large variations in human ear shape and complicated material behavior in both ear canal and ear plug. Generating a set of human ear models required the use of large and small scale 3D scanning technologies to create geometries representing both external and internal structures. Multiple material layers were used to approximate the actual layers in the region.
The model simulated the insertion and stress relaxation of the hearing protection devices. Results from these models were compared against discomfort measured in use. The model results show that discomfort is a function of contact pressure and area. Average contact pressure and total contact force were identified as the key metrics that correlate to comfort ratings from the use studies

The emergence of simulation data management software packages provides an opportunity to both streamline simulation processes and further leverage the impact of simulation results. The nimble mechanism for process automation offered by SIMULIA SLM (Simulation Lifecycle Management) product reduces simulation turnaround by establishing connections between and managing simulation stages while allowing interactive components, such as Abaqus/CAE, to provide rich functionality. A strategy of combining a server based management system with local interactive components allows new and existing simulation processes to be quickly encapsulated into a streamlined tool. The management system (SLM) tracks data pedigree and provides sophisticated search/retrieval tools for simulation related data. The results are faster simulation cycles (build/run/analyze) and improved quality control of simulation activities (formalized process and associated control mechanism). Achieving the correct balance between adaptability and rigidity within a simulation process is a key aspect to consider as SLM is configured to a specific target user group. For example, expert users can take advantage of process streamlining and data management with full access to interactive application capability providing maximum flexibility. At the other extreme, a directed process with intentionally limited choices may be appropriate for a non-expert user. Combining a configurable process and data management tool (SLM) and customized interactive components (i.e., Abaqus/CAE) provides a common environment for teams to realize full value from simulation efforts. This paper uses two applications using SLM in conjunction with interactive tools to provide formalized simulation processes to illustrate the advantages of such a strategy.

The work presented in this paper details the development of a finite element (FE) model
of a soccer ball, allowing for a greater understanding of the performance of soccer balls under
dynamic conditions that are representative of play. The model consists of composite shell elements that include a hyperelastic strain energy potential equation to define the latex bladder layer and a plane stress orthotropic elastic material model to define the anisotropic woven fabric outer panels. The model was validated through a series of experimental tests whereby the ball was impacted normal to a rigid plate at an inbound velocity of approximately 34 ms-1 (76 mph), with each impact recorded using high speed video (HSV) techniques. It was found that the combined effects of ball design and panel material anisotropy caused impact properties such as impact contact time, deformation, and the 2D shape taken up by the ball at maximum deformation, to vary with pre-impact ball orientation. The model showed good agreement with the experimental measurements and was able to represent the effects of anisotropy in ball design.

A preliminary model of shaving has been consuucted using the ABAQUS/Explicit solver. It consists of a single hair mounted in a block of hi-layered skin. across which a razor traverses. Modelling features include ( l) deformable and non-deformable contact boundary conditions between the razor. skin and hair. (2) material moduli ranging over seven orders of magnitude and (3) infrnite clements to simulate far-field boundarv conditions. T11e skin material properties are described using a large strain. viscoelastic material modeL based on experimental test data. Current work is focussing on the modelling of hair cutting. The purpose of this paper is to highlight the problems associated with developing a physiological model and the hurdles faced in simulating hair cutting with the ABAQUS/Explicit solver.