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.
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.
Pullout resistance of driven foundation piles often in-creases with time in a process known as pile “setup.” The consolidation of the surrounding soil after the pile is driven plays a dominant role in the setup process. Finite element modeling of pile setup can help in obtaining reli-able estimates of the increase in pile resistance, which would allow for reductions in pile lengths, pile sections, or sizes of the pile driving equipment.
Finite element modeling of prestressed concrete contain-ment vessels (PCCVs, Ref. 1) for nuclear power plants poses special challenges. PCCVs, which are heavily rein-forced structures, are designed to deform beyond the cracking limits of the concrete. Abaqus has been used extensively for analyzing such structures in the nuclear utility industry (Ref. 2) and can be used to assess and improve the performance of these and other similar rein-forced concrete structures.
Construction of earthen dams entails sequential place-ment and compaction of soil layers and the subsequent fill-up of the embanked reservoir. In the design of earthen dams, two potentially critical events must be considered: the rapid emptying (or drawdown) of the reservoir and the dynamic loading of an earthquake. The possibility of dam failure in these situations depends on the respective build-up and dissipation of the fluid pore pressure in the soil.
Space flight re-entry vehicles impart highly dynamic loads on the crew and/or payload during a water landing. To understand the behavior of the vehicle/payload system as it makes impact, a predictive framework that can simultaneously model the structure, the highly deformable landing medium (water or soil), and their interaction is required. The coupled Eulerian-Lagrangian (CEL) method in Abaqus/Explicit provides the means for capturing these complex physical phenomena.
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.
Bird strikes cost the United States aviation industry tens of millions of dollars annually in aircraft damage and schedule delays. Increasing the ability of the aircraft to resist bird strike induced damage is one part of an overall approach to mitigating this expense . Experimental bird strike testing is part of the certification process for certain aircraft component designs. If a subset of the tests can be replaced with computational simula-tion, the cost of the prototype testing can be reduced.
A mechanical system, such as aircraft landing gear, can have a large number of parts that interact in a complex nonlinear fashion. The challenge of simulating such a sys-tem lies not only in capturing the correct physical behavior but in using efficient analysis techniques. Different levels of modeling abstraction may be appropriate for different stages of the design process. Initial sizing and kinematics can be studied with a partially rigid representation, while final designs are more often analyzed with fully meshed flexible geometry.
Composite materials offer significant design advantages in the aerospace industry. High strength and light weight are the two most attractive features for aircraft and space vehicle designs. However, their complex material behav-ior makes analysis of these structures a significant chal-lenge, particularly in a high speed impact event. The ad-vanced composite modeling and industry leading simula-tion capabilities of Abaqus/Explicit make analysis of these challenging materials straightforward and allow accurate prediction of ballistic limit, damage and failure.
The use of composite materials in the aerospace industry is increasing. Composite materials offer a relatively high strength-to-weight ratio as well as the ability to create large, integrated structures. One composite component can replace 10 or more traditional metal parts, which can dramatically reduce manufacturing time and cost.