Modeling of Ultra High Strength Steel Sandwiches with Lightweight Cores

Proceedings

Document identifier: oai:DiVA.org:ltu-75752
Keyword: Engineering and Technology, Mechanical Engineering, Applied Mechanics, Teknik och teknologier, Maskinteknik, Teknisk mekanik, Hållfasthetslära, Solid Mechanics
Publication year: 2019
Relevant Sustainable Development Goals (SDGs):
SDG 9 Industry, innovation and infrastructureSDG 11 Sustainable cities and communities
The SDG label(s) above have been assigned by OSDG.ai

Abstract:

Legislation, du to greenhouse gas emissions, is forcing the automotive industry to reduce emissions and energy consumption. High-performance lightweight materials and structures are essential for meeting these demands. In this work, two types of lightweight sandwich materials are investigated and developed; one intended for crash applications (Type I) and another for stiffness applications (Type II). In order to predict the final properties of the sandwich materials, numerical modeling strategies are established. To achieve reasonable computational time, homogenization is adopted to overcome the complex core geometries of the sandwich materials. Type I, based on press-hardened boron steel, consists of a perforated core between two face plates. Evaluation of energy absorption during crash is conducted by utilizing numerical deformation models of a hat-profile geometry. The intention is to compare the energy absorption of the hat-profile based on the Type I sandwich to a hat-profile based on solid steel with equivalent weight. Type II, based on press-hardened boron steel, consists of a bidirectionally corrugated core between two face plates. The geometry of the bidirectional core requires a large amount of finite elements for precise discretization, causing impractical simulation times. This is adressed by suggesting an equivalent material formulation, to reduce the computational time. The results from Type I indicate an increased specific energy absorption capacity of 20 % as compared to solid steel. From the equivalent material procedure of Type II, it is found that the computational cost is reduced by 95 % with a maintained accuracy for structural stiffness. Validation is carried out by subjecting the sandwich to three-point bending. Good agreement is found between numerical and experimental data. Thus, this work shows that sandwich materials are an interesting and promising approach for reducing weight of vehicle components while maintaining performance, in terms of stiffness and crashworthiness.   

Authors

Samuel Hammarberg

Luleå tekniska universitet; Material- och solidmekanik
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Jörgen Kajberg

Luleå tekniska universitet; Material- och solidmekanik
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Pär Jonsén

Luleå tekniska universitet; Material- och solidmekanik
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