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Session 8

A modified approach for simulating complex compound structures within early design steps
Owing to increasing relevance of lightweight design the deployment of compound structures with their beneficial material characteristics becomes more and more important. These growing demands for lightweight design cannot be met by improving constructive details at the end of the development cycle. On the contrary already the early design steps have to be exploited adequately, since these steps offer the highest freedom of design. The present paper shows a modified approach for simulating complex compound structures adapted to the requirements of early design steps. The basic idea is overlapping several basic material models (characterized by a low amount of input parameters) within one finite shell formulation to describe any combination of material effects. The benefit of the approach is a more accurate simulation of complex compound structures with reduced modeling effort. A validation of this phenomenological material superposition approach is performed by opposing the results of virtual material tests to experimental results published in the literature.
Investigation and Application of Multi-Disciplinary Optimization for Automotive Body-in-White Development
A process has been created for applying multi-disciplinary optimization (MDO) during the development of an automotive body-in-white (BIW) structure. The initial phase evaluated the performance of several different optimization algorithms when applied to structural MDO problems. From this testing, two algorithms were chosen for further study, one of these being sequential metamodeling with domain reduction (SRSM) found within LS-OPT. To use the LS-OPT optimization software effectively within a production environment, adaptations were made to integrate it into an established CAE infrastructure. This involved developing a LS-OPT server and architecture for the parallel job submission and queuing required in the MDO process. This enabled LS- OPT to act as an integral part of the enterprise CAE architecture as opposed to a standalone tool. Within this integrated environment, the SRSM method has been applied to an MDO process that combines 7 load cases and takes into account crash and NVH requirements. The objective of the MDO was to minimize mass while constraints enforced the performance requirements of each load case. The thicknesses of 35 parts were considered in this MDO. The application of the SRSM MDO strategy resulted in an optimized design with a 6% weight reduction for the portion of the BIW considered. The optimized design was determined with reasonable computational resources and time considering the computational intensity of the analysis.
Parametric Modelling of Simplified Car Models for Assessment of Frontal Impact Compatibility
The aim of the FIMCAR project (co-funded by the European Commission within the 7th Framework Programme) is to develop and validate a frontal impact assessment approach that considers self and partner protection. In order to assess the influence of different test procedures and metrics on car- to-car compatibility a huge simulation programme is envisaged. However, car-to-car simulations with models of different car manufacturers are almost impossible because of confidentiality. In addition the detailed models of the car manufacturers are complicated to optimise for different assessment procedures and are consuming considerable computational efforts. In order to overcome these problems, parametric car models were built allowing fast modifications. By simplifying the models, computational efforts are reduced. Due to the rapid increase of the calculation power the level of detail in car models has reached a very high level. At the same time the number of discretised parts drops and smaller structures are considered in the meshing process. However, only a few structures are mainly responsible for the frontal crash behaviour of the vehicle. A high variability of mounting positions, connections and stiffness of parts of a car’s front–end offers a big potential in investigations of frontal impact vehicle structures. However, the modification of these criteria is time consuming, especially the modification of a given FE-mesh or geometry model. The software SFE CONCEPTTM offers the possibility to establish an implicit parametric car model in an easy and fast way. A variable geometric model is created by the specification of base lines and cross sections for the different parts. The modification of a structure with respect to connected parts is one of the advantages of SFE CONCEPTTM. Through manipulation of the implicit parameters, new structure concepts and /or small variations of a part’s dimensions can be established. After all the software is able to mesh the geometry and export the data for different solvers like LS-Dyna. In that way it is possible to generate a manifold number of structures, in a fast and certain way which is necessary for the investigations of the influence of these structures in frontal impact compatibility. The set up of the FE model is adapted to the export data structure of SFE CONCEPTTM. This way the models can be simulated directly after modification without further post-editing.
The ACP Process Applied to the FutureSteelVehicle Project: The Future of Product Design and Development
WorldAutoSteel launched Phase 2 of its FutureSteelVehicle programme (FSV) with the aim to help automakers optimise steel body structures for electrified vehicles. The Phase 2 objective is to develop detailed design concepts and fully optimise a radically different body structure for a compact Battery Electric Vehicle (BEV) in production in the 2015-2020 timeframe. This paper will provide an overview of the product design methodology and how it was applied to WorldAutoSteel FutureSteelVehicle (FSV) program and result in 35% BIW mass reduction and how it has continued to evolve with each application. The Accelerated Concept to Product (ACP) ProcessTM was applied in this project. The ACP ProcessTM is a proprietary, performance-driven, holistic product design development method, which is based on design optimization. ACP incorporates the use of multiple CAE tools in a systematic process to generate the optimal design solution. The ACP ProcessTM is a methodology that provides solutions, which address the challenges facing the modern product development environment. It achieves this by synchronizing the individual facets of the product development process, resulting in an overall reduction in development costs and time to market. Material selection and utilization, product performance requirements and manufacturing and assembly processes are all considered as early as possible in the design cycle. The resulting design offers a robust and highly efficient solution; which when combined with the strength and design flexibility of Advanced High Strength Steel (AHSS) or other materials; facilitates significant mass reduction for the final design. For the development of a vehicle structure, the methodology offers four key benefits, including a demonstrated capability to reduce product development costs by 40%, reduce product mass by 25% and more, improve product performance (stiffness, durability, NVH, crash/safety, durability) as well as improve fuel efficiency based on the mass reduction results. The paper will further disclose the results of the FSV programme, detailing steel body structure concepts for the aforementioned vehicles that meet aggressive mass targets of 190 kg, while meeting 2015-2020 crash performance objectives as well as total life cycle Greenhouse Gas emissions targets. FSV’s steel portfolio, including over 20 different AHSS grades representing materials expected to be commercially available in the 2015 – 2020 technology horizon, is utilised during the material selection process with the aid of full vehicle analysis to determine material grade and thickness optimisation. Achievement of such aggressive weight reduction with steel will set a new standard for vehicle design approaches for the future. Radically different powertrains, such as the BEV and the PHEV proposed for FutureSteelVehicle, and their related systems make new demands for increasingly efficient body components to handle the new loads. This will require innovative use of AHSS grades and steel technologies to develop structures that are stronger, leaner, greener and affordable. The presentation will explain the “state of the future” design optimisation process used and feature the aggressive steel concepts for structural subsystems incorporated into the FSV structure.