Methodology for multiscale design and optimization of lattice core sandwich structures for lightweight hopper railcars

Abstract

This research is focused on developing new lightweight structures for railcars based on a pre-selected material, i.e. Al 2099. The goal is to design a new sandwich structure with an octet truss lattice core for a floor panel of a hopper freight railcar designed to meet North American standards. For that, mesoscale to macroscale design of the sandwich panel was performed. In mesoscale design, relative density, elastic properties, strength properties, and failure criterion of the lattice unit cell were investigated. In the next step, these properties were used as inputs for macroscale design, i.e. design of the whole sandwich structure. Multiple failure modes associated with the lateral loading of a sandwich panel were analyzed. These equations in conjunction with the minimum weight target led to an optimization problem, and the minimum required thicknesses were obtained. Finally, the new optimized design was validated by comparing different finite element simulations with the exact analytical equations. By using this type of structure, a 53% weight reduction was achieved on the floor panel which ultimately led to an estimated 12.5% reduction in the weight of the whole freight railcar body.

Detecting the influence of uneven loading of the brake shoe in a freight car bogie on its strength

“…The finite element model was built using isoparametric tetrahedra [26][27][28][29]. Their number was determined by the graphoanalytical method [30][31][32][33][34]. In this case, the number of nodes of the model was 7017, and elements -28970, with the maximum size of 15 mm and the minimum size of 3 mm.…”

Damage-induced failure analysis of additively manufactured lattice materials under uniaxial and multiaxial tension

“…see (Mirzaali et al, 2020;Wang, 2018). In the last decade, the advancements in additive manufacturing enabled the fabrication of complex micro-architectures and facilitated the adoption of lattice materials in wide range of industries (Molavitabrizi and Laliberte, 2020). The elastic and/or elastoplastic behavior of these materials has long been investigated, e.g.…”

Design optimization of hopper cars employing functionally graded honeycomb sandwich panels

“…9,10 Molavitabrizi and Laliberte investigated the multiscale design optimization of hopper cars using octet core lattices optimized at the microstructural level and then extrapolated to the mesoscale. 11 Lee et al employed a multiscale approach whereby topology optimization was used to determine where corrugation is to be concentrated in a rail car and then subsequently those panels were sized. 12 Harte et al employed a multiscale approach to determine ideal CFRP shape and layer sizing of a passenger LRV.…”