Failure of pharmaceutical packaging incurs the risk of negative health outcomes and expensive product recalls. Pre-filled syringes represent a growing portion of the drug packaging market. During its working life, a syringe ex-periences stresses that may result in material damage. Specifically, the syringe barrel may develop microcracks that coalesce and propagate, causing the syringe to frac-ture and its contents to lose sterility. Abaqus/Standard offers the technologies necessary to include fracture and failure in the syringe design process. The extended finite element method (XFEM) allows for the analysis of crack initiation and propagation along an arbitrary, solution dependent path without the need for remeshing.

In the design of hearing instruments it is important to achieve the highest possible gain without introducing feedback between the microphone and loudspeaker. With more gain, a larger hearing loss can be accommodated and a greater number of users benefit.
Maximizing gain while minimizing the possibility of feed-back requires an optimal choice of design parameters. In this Technology Brief, we outline how Abaqus/Standard and Isight can be combined in a process to optimize the vibro-acoustic characteristics of hearing instruments.

Biodegradable polymeric stents must provide mechanical support of the stenotic artery wall for up to several months while being subjected to cyclic loading that af-fects the degradation process. To understand the appli-cability and efficacy of biodegradable polymers, a hypere-lastic constitutive model is developed for materials under-going deformation-induced degradation. The model was implemented in Abaqus/Standard and applied to a com-monly used biodegradable polymer system, poly (L-lactic acid) (PLLA).

In the adaptive bone remodeling process, the density of bone tissue changes over time according to the load it sustains. Elevated loads produce increases in bone den-sity while reduced loads cause reduction of bone density. The long term success of an orthopedic implant can be better predicted by including this process in the design workflow. In this Technology Brief, we demonstrate the Abaqus/Standard implementation of one of the leading bone re-modeling algorithms. User subroutine USDFLD is em-ployed to capture solution dependent material properties, and the approach is used in the analysis of a total hip re-placement design.

Electroencephalography (EEG) is used to obtain informa-tion about the electrical activity in the brain and is rou-tinely used to diagnose neurological abnormalities. The inverse problem in EEG refers to the procedure of locat-ing electrical sources in the brain from the extracranial electrical field measured on the scalp. The solution of the inverse problem requires the forward calculation of the electric field for a given source location. The significance of the inclusion of inhomogeneity and anisotropy in the electrical conductivity of the brain tissue in the forward solution is not well understood.

The ability of a finite element simulation to accurately capture the behavior of a structure strongly depends on the chosen material model. Not only must it be applica-ble to the given class of materials and intended applica-tion, it must be properly calibrated. Sophisticated material models that use many parameters can present a challenging calibration task. Optimization techniques can be employed to determine suitable pa-rameter values. In this Technology Brief, HEEDS, an optimization tool developed by Red Cedar Technology, will be used in conjunction with Abaqus to determine the parameters needed to model the viscoelastic behavior of a rate-dependent vinyl material.

The superelastic, shape memory, biocompatibility, and fatigue properties of Nitinol, a nickel-titanium alloy, have made the material attractive for medical devices such as cardiovascular stents. However, it is a complex material and difficult to process. Finite element modeling of Nitinol devices such as stents reduces testing and time-to-market by allowing the designer to simulate the stent manufacturing and deployment processes. The constitu-tive models for superelastic alloys are available as user subroutine libraries for both Abaqus/Standard and Abaqus/Explicit.

Trabecular bone must withstand the loads that arise during daily activities as well as those due to trauma. Investigation of the mechanical properties of trabecular bone presents a challenge due to its high porosity and complex architecture, both of which vary substantially between anatomic sites and across individuals. While Micro Finite Element (μFE) analysis of trabecular bone is the most commonly used method to analyze trabecular bone mechanical behavior, the large size of these models has forced researchers to use custom codes and linear analysis. The nonlinear capabilities in Abaqus allow efficient analysis of these models and provide  answers to important research questions.

Metal welding processes are employed in various indus-tries. Gas welding techniques use the heat from a flame to melt the parts to be joined and a filler material simulta-neously. Extreme thermal loading is applied to the parts being joined, and complex material responses are initi-ated. The steep, localized thermal gradients result in stress concentrations in the welding zone. Consequently, modeling and simulation of welding processes are often complex and challenging. In this technology brief the use of Abaqus for this class of problems is discussed and an example analysis is presented.

Filament winding has become a popular construction technique in a wide variety of industries for creating com-posite structures with high stiffness-to-weight ratios. The difficulty in accurately analyzing the structural behavior of a filament wound body derives from the continually vary-ing orientation of the filaments. The standard capabilities of commercial finite element codes are inadequate to model the spatial variation of fiber orientation in a practical way.
In this Technology Brief, an Abaqus/CAE plug-in for the analysis of filament wound composite pressure vessels is presented. The application allows the user to create, run, and post process a finite element model and allows for detailed specification of structural geometry and winding layout parameters.

Abaqus/CAE includes modeling and postprocessing capabilities for fracture mechanics analyses. These features provide interactive access to the contour integral fracture mechanics technology in Abaqus/Standard. Several fracture-specific tools are available, such as those for creating seam cracks, defining singularities, selecting the crack front and crack tip, defining q-vectors or normals to the crack front, and creating focused meshes. With these tools models can be created to estimate J-integrals, stress intensity factors, and crack propagation directions.

The solder joints of surface-mount electronic devices may fail because of low-cycle fatigue. Combined with differences in thermal expansion properties for the various components of the assembly, cyclic thermal loading induces stress reversals and the potential accumulation of inelastic strain in the joints. Predicting solder joint fatigue life requires a thorough understanding of the deformation and failure mechanisms of the solder alloy and an accurate
calculation of the stresses and strains in the joint. In this Technology Brief, a thermal fatigue analysis of a surface mount electronic assembly is conducted using the Abaqus/Standard low-cycle fatigue capability. With a cost efficient direct cyclic procedure, material models for

Lead and its compounds have been widely used for many years in the electronics industry. However, the global demand to reduce the use of hazardous materials has compelled electronics manufacturers to consider the use of lead-free materials in future products. This transition has heightened the necessity for new finite element material models that can be used to evaluate the reliability of lead-free solders. Along with extensive nonlinear analysis capabilities, Abaqus/Standard includes a variety of creep models - including those applicable to lead-free solders, making it a reliable design tool for the electronics industry.

The computational analysis of MEMS (Micro Electro Me-chanical systems) devices poses distinctive challenges, requiring software that provides flexible modeling tools, enables the coupling of multiple physical phenomena, and considers the integration of the devices into their macro-scale surroundings. To meet these requirements, Abaqus partners with developers of commercially available MEMS software by providing the necessary finite element analy-sis capabilities to these packages.

Portable, hand-held electronic devices have become commonplace due to their small size and light weight. It is inevitable that such devices will occasionally experience the shock loading associated with being dropped. Ac-counting for this loading scenario in the design process, both analytically and experimentally, allows for the devel-opment of more durable products. The ability to simulate drop-type loading reliably reduces the dependency on experimental testing. Abaqus/Explicit has been used ex-tensively to examine the behavior of electronic devices experiencing mechanical shock loading.

The interaction of a subsea pipeline with the seabed is a complex phenomenon. Operational  loads can cause a subsea pipeline to buckle or “walk” over the seabed, leading to very high pipeline stresses. In some cases however, the buckling phenomena can be beneficially used to
relieve excessive stresses by allowing the pipeline to deform at pre-determined locations. The understanding and prediction of these phenomena is therefore crucial for subsea pipeline design.

Coiled tubing is used in a variety of oil well operations including drilling, completions, and  remedial activities. For each of these applications coiled tubing offers the benefits of reduced costs, speed, and reduced environmental impact. Coiled tubing possesses a limitation  however, in that it may buckle in service. In this situation the tubing may be damaged, and operations may be delayed or disrupted. In this Technology Brief, we provide a methodology for evaluating the buckling behavior of coiled wellbore tube.

Mesh construction is a key consideration in the course of building a finite element model. The quality of the analysis results depends on the quality of the mesh; arriving at an acceptable solution requires judicious meshing choices. Specifically, the analyst must consider the type of ele-ments and the density of the mesh, which is often varied throughout the model, with more refinement in critical re-gions. These considerations need to be balanced against the desire to minimize analysis cost in terms of preproc-essing effort, analysis run time, and computer resources.

In earth penetration events the projectile generally strikes the target at an oblique angle. As a result, the projectile is subjected to a multi-axial force and acceleration history through impact. The effectiveness of an earth penetration system is enhanced by the ability to withstand severe

The Dynamic Design Analysis Method (DDAM) is a U.S. Navy methodology for qualifying shipboard equipment and supporting structures for survival of shock loading due to
underwater explosions (UNDEX). The DDAM is a regimented collection of procedures that utilize estimates of the peak linear dynamic response of ship equipment and structures
obtained from normal mode response spectrum analyses. The response spectra are usually based upon empirically obtained Shock Design Values (SDVs) that are dependent on the type of ship, mounting location, direction of attack, response frequencies, and overall survivability

Accurate numerical modeling of the shock response of marine structures is of considerable importance in their design since the cost associated with physical testing is often prohibitive. Along with the shock response calibra-tion, designers often have to grapple with opposing fac-tors while trying to optimize performance during operating conditions. Abaqus allows for the analysis of both the structural integrity and acoustic radiation in such cases.
In this technology brief two related but distinct analyses are examined. First, the shock response of an example structure due to a shock event is considered. Second, the steady-state acoustic field established due to machinery-induced vibrations within and around the structure is esti-mated.

Residual stresses may be introduced into plastic parts produced by the injection molding process. As a result, the part may warp or experience a reduction in strength. The design of an injection molded product can be improved if the effect of residual stresses on the final shape and performance of the product are predicted accurately. Abaqus and Moldflow can be used for this purpose. The residual stresses generated by the solidifi-cation of the plastic material are computed by Moldflow and transferred to Abaqus using the Abaqus Interface for Moldflow. The component can then be structurally analyzed with Abaqus to determine warpage and/or response to in-service loading. In this Technology Brief, this methodology is demonstrated with two case studies.

A key factor in the design of bottles and packaging con-tainers is performance during conveying. The ability of a bottle to remain standing while traveling through a con-veying plant for production, cleaning, filling, packaging, etc. allows that plant to be automated. If bottles fall or jam during conveying then human intervention is required to correct the situation. Finite element analysis can be used to verify new bottle designs and ensure that changes to current designs will not cause a reduction in conveying performance.

Hot rolling is a basic metal forming technique that is used to transform preformed shapes into final products or forms that are suitable for further processing. The process typically involves passing heated stock pieces through multiple sets of forming rolls until the desired cross-sectional shape is achieved. The important aspects of this manufacturing operation are the elongation and spread of the material during the rolling process. Abaqus contains all the features necessary to model this process and has been used extensively within the metal processing indus-try to optimize roll pass designs.

Composite structures often have a higher capacity for ab-sorbing energy than their metal counterparts. The crush-ing behavior of composite materials is complex, and the inclusion of composite components in vehicles for crash protection can necessitate expensive experimental test-ing. The ability to computationally simulate the crushing response of composite structures can significantly shorten the product development cycle and reduce cost in the aerospace, automotive, and railway industries. In this Technology Brief, we describe a methodology for modeling the crushing behavior of composite structures using Abaqus/Explicit.