software

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

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.

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.

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.

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.

The uniform pressure method (UPM) approach to simulat-ing airbag deployment has been widely used in the auto-mobile safety industry. The defining assumption of UPM, specifically that pressure in the airbag is spatially uniform during inflation, makes the approach most applicable for „in-position‟ (IP) analyses with fully inflated airbags. In contrast, an analysis may be characterized as „out-of-position‟ (OoP) if the occupant interacts with the airbag before it is fully deployed.

In a traditional automobile noise, vibration and harshness (NVH) analysis, stationary tires are defined and subjected to vertical dynamic loading. The actual operating condi-tions of a tire involve rolling however, and the vibration characteristics of rolling tires are considerably different from those of stationary tires. Abaqus offers a methodology to include the pre-loading and gyroscopic effects of rolling tires in a forced response dynamic analysis of the moving vehicle.

In the automobile industry, kinematics and compliance (K&C) testing is used to evaluate the ride and handling performance of an automobile. The traditional approach to numerical simulation of K&C testing involves the use of multi-body dynamics software, which simplifies the phys-ics by introducing rigid body assumptions. In this Technology Brief, a new methodology for K&C simulation is demonstrated using Abaqus/Standard.

Accurate simulation of an anti-lock brake system (ABS) requires detailed modeling of separate subsystems in dif-ferent physical domains. Creating refined models of the brake, wheel, and control components with a single analy-sis tool is difficult, if not impossible. The strategy of co-simulation can be adopted to meet this challenge; differ-ent simulation tools can be used simultaneously to create multi-disciplinary and multi-domain coupling. In this Technology Brief, a co-simulation approach using Abaqus and Dymola is used to achieve a realistic system-level simulation of an ABS.

The Biofidelic Rear Impact Dummy (BioRID-II) hardware model has been developed to measure automotive seat and head restraint system performance in low-speed rear end crashes. It has also been used to further the under-standing of whiplash injuries. This technology brief fo-cuses on the Abaqus BioRID-II finite element model, which has been developed in cooperation with the Ger-man Association for Research in Automobile Technology FAT. The capabilities of the model will be described, and a comparison with experimental data is shown.

Tires are the only load transfer mechanism between a vehicle’s suspension and the road. Consequently, tire vibration has a significant impact on ride quality and vehicle interior noise.

The B-pillar is an important load carrying component of any automobile body. It is a primary support structure for the roof, and is typically a thin-walled, spot-welded, closed-section structure made from high strength steels. As part of the validation process, the B-pillar can be ex-perimentally loaded at quasi-static rates until failure†. The force and displacement of the impactor are measured to get valuable insight into the stiffness characteristics of the structure.

During product development, design engineers often have the freedom to modify a number of parameters. However, any design modification requires validation to ensure the satisfaction of requirements for all load cases. With Abaqus for CATIA V5 (AFC), nonlinear finite element technology is made available within the CATIA environment, allowing design engineers to efficiently incorporate accurate stress analysis into the design process. In this Technology Brief two approaches are described to illustrate the productivity gains possible with AFC.

This technology brief illustrates typical mode-based noise, vibration, and harshness (NVH) analyses of a full automobile model using the Abaqus product suite. Abaqus/AMS, the automatic multi-level substructuring eigensolver, is used to compute the eigensolution. A steady-state dynamic analysis is then performed in Abaqus/Standard. The significant performance benefit of using Abaqus/AMS and the SIM-based linear dynamics architecture will be demonstrated for uncoupled structural and coupled structural-acoustic analyses.

A methodology to study the sound radiation of engine valve covers is presented. The analysis process uses a nonlinear static simulation followed by a steady state dy-namics simulation to determine the sound pressure field due to the vibration of the engine cover. The effects of assembly loads are included. The methodology is dem-onstrated with two representative engine valve covers using acoustic finite and/or infinite element methods. Good correlation between the analysis results and avail-able experimental data is achieved.

The National Highway Traffic Safety Administration (NHTSA) mandates the use of certain test procedures to determine automobile roof crush resistance. In the test the force-deflection behavior of the roof structure is meas-ured by quasi-statically pressing a precisely positioned rigid plate against the automobile. As part of the design process, the test is often simulated analytically. As with many quasi-static processes, the roof crush resis-tance test can be simulated in Abaqus/Standard or Abaqus/Explicit.

A methodology to study friction-induced squeal in a com-plete automotive disc brake assembly is presented. The analysis process uses a nonlinear static simulation se-quence followed by a complex eigenvalue extraction to determine the dynamic instabilities that are manifested as unwanted noise. The effects of assembly loads; nonuni-form contact pressure between the brake linings and disc; velocity-, temperature-, and pressure-dependent friction coefficients; friction-induced damping; and lining wear can be included. The methodology is demonstrated with a representative disc brake assembly.

Spot-welded, thin-walled curved beams, which constitute the main structural members in many automobile and other ground vehicle body structures, play a significant role in absorbing energy during a collision. Due to their extensive use, it is important to study the collapse charac-teristics of these curved members (Ref. 1). Abaqus/Explicit can be used effectively to simulate the quasi-static collapse of spot-welded structural members accu-rately.

A wide range of loading conditions must be considered in the design of a tire. Computational simulations of a quasi-static, steady-state dynamic and nonlinear transient dy-namic nature must be completed. In addition, the com-plexity and size of typical tire models highlight the need for efficient solution techniques.

Spudcans are conical footings used as foundations for offshore platforms. Installation in soft marine soil forces them deeply into the seabed, inducing gross motion and severe plastic deformation in the soil. A pure Lagrangian-based finite element approach for modeling spudcan installation and extraction can be very difficult. Because the mesh moves with the material, ele-ment distortion typically accompanies severe deformation and convergence difficulties follow.

On August 1, 2007, the I-35W highway bridge over the Mississippi river in Minneapolis, MN collapsed. The sub-sequent National Transportation Safety Board (NTSB) investigation identified the U10W truss node as a likely initiation site for the failure. (Bridge main truss nodes were numbered from the south starting at 0. U indicates a node along the upper chord, and L indicates a node along the lower chord. E and W indicate a node on the east or west truss) [1, 2, 3].

Assessing the strength of soil slopes and investigating the means for increasing their safety against failure are cru-cial in construction projects involving large soil masses. Slope stability analyses have traditionally been performed using a limit state approach. However, any presence of reinforcement or local heterogeneity necessitates the use of numerical techniques such as finite element analysis. Abaqus/Standard can be used for modeling reinforced soils and can thus help geotechnical engineers in deter-mining optimal reinforcement sizes and placement con-figurations.