In this review paper, we show that the current battery electric vehicle (BEV) scale-up relies on several key technologies which all have detailed roadmaps with good track records for being met. These ...roadmaps include lightweighting of vehicle bodies using lightweight materials and architecture/structure design, and improvements in BEV powertrain with regard to the powertrain architecture/system design, battery and motor technology development. However, as technology take-up accelerates, our novel analysis suggests supply of zero carbon electricity may become a serious constraint. We find that the technical potential for abating the demand for electricity through powertrain and lightweighting improvements is just over a quarter of the projected total. Four promising avenues to mitigating this constraint – battery reusing and interoperable charging technology, shared mobility, advanced sensing technology, and novel compact space frame construction - are explored in brief, potentially enabling the large-scale deployment of BEVs without exhausting the supply of non-emitting electricity.
•Technological roadmaps for shifting to BEVs are reviewed.•How far technology improvements can overcome cost and range barriers of BEVs are analysed.•Detailed energy analysis for various scenarios of BEV technology take-up is conducted.•Supply of zero carbon electricity is likely to be a serious challenge for the full transition to BEVs.•Potential technological breakthroughs for mitigating the electricity constraint are outlooked.
Lightweight design is gaining in importance for design for sustainability due to its capability to reduce weight, conserve materials, and enhance energy efficiency. However, environmental ...sustainability encompasses a broader spectrum, including, for instance, a responsible resource management as well as material recyclability. Despite their shared objective of optimizing resource consumption, can lightweight design indeed be substantiated as sustainable, and if so, how?
Therefore, this contribution emphasizes a systematic approach for the analysis of environmental effects caused by property changes resulting from the implementation of lightweight design strategies (system, form, material and manufacturing lightweight design) in products. Thereby, life cycle issues of the lightweight design strategies are evaluated on the basis of a holistic life cycle perspective. Finally, the interrelationships between lightweight design strategies and sustainability strategies (eco-efficiency, eco-effectiveness, and sufficiency) are discussed. In future, the presented approach supports both positive synergies as well as negative conflicts of lightweight design and design for sustainability to be efficiently and strategically evaluated throughout the design process, so that holistically optimized lightweight and sustainable products can thus be created.
•Novel interpenetrating lattice structures with minimal surfaces are designed.•Interpenetrating parameter controls mechanical properties and deformation behaviors.•Interpenetrating lattice structures ...avoid large drop in stress after failure.•Multiscale optimization is proposed to improve the structure's stiffness.
Compared to single-phase structures, interpenetrating lattice structures display the potential to achieve a wide range of tailorable physical and mechanical properties. Herein, we present a novel class of interpenetrating lattice structures based on triply periodic minimal surfaces. Using representative volume elements applied with the periodic boundary conditions, the contributions of the volume fraction and the interpenetrating parameter, a measure of the ratio of the two phases, on the mechanical properties and deformation behavior of the interpenetrating lattice structures are investigated. Results show that the mechanical properties are highly dependent on the interpenetrating parameter, and isotropic elasticity can be achieved at a particular value. Moreover, the uniaxial and shear deformation mechanisms (bending or stretching behavior) can be easily changed by adjusting the interpenetrating parameter. Our new interpenetrating lattice designs are experimentally validated using 3D-printed samples. Finally, a new multiscale optimization framework, based on simultaneously optimizing the distribution of the volume fraction and the interpenetrating parameter, is developed. Compared to the traditional optimized designs that only consider the volume fraction, the proposed optimized design reduces the structural compliance by more than 10.85%, confirming the effectiveness of the proposed optimization framework for lightweight applications.
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The performance of advanced and lightweight 316L stainless steel lattice structures fabricated by selective laser melting (SLM) was investigated using a range of laser energy densities (LED). A ...unique tetrakaidecahedron cell type was designed to construct a periodic lattice structure, which was compared with two common lattice structures of different unit cell topologies and deformation behaviors using mechanical property and quasi-static energy absorption. It was found that tetrakaidecahedron structure deserved good compressive properties and energy absorption capabilities. The fabricated strut morphology and internal porosity were investigated using confocal and scanning electron microscopy to correlate with the compressive properties of the structure. The porosity was found to increase firstly and then fluctuate smoothly with increasing LED, similar to yield strength. The yield strength and compression modulus were not independent of porosity, indicating that further improvements can be achieved by SLM process optimization. Meanwhile, nonlinear finite element analysis was used to analyze their compressive response and fracture behavior. Our results highlighted that a high performing unit cell geometry can be used for energy absorption and lightweight manufacturing applications of lattice structures.
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•Constructing a periodic lattice structure using a unique tetrakaidecahedron cell design.•Characterization of four lattices’ mechanical properties using experimental and finite element analysis validations.•A lattice based on a tetrakaidecahedron unit cell provides optimum mechanical properties.•Linear energy density influences the strut morphology, internal porosity and mechanical properties of the lattice structure.
Infrared based visual perception is important for night vision of autonomous vehicles, unmanned aerial vehicles (UAVs), etc. Semantic segmentation based on deep learning is one of the key techniques ...for infrared vision-based perception systems. Currently, most of the advanced methods are based on Transformers, which can achieve favorable segmentation accuracy. However, the high complexity of Transformers prevents them from meeting the real-time requirement of inference speed in resource constrained applications. In view of this, we suggest several lightweight designs that significantly reduce existing computational complexity. In order to maintain the segmentation accuracy, we further introduce the recent vision big model — Segment Anything Model (SAM) to supply auxiliary supervisory signals while training models. Based on these designs, we propose a lightweight segmentation network termed SMALNet (Segment Anything Model Aided Lightweight Network). Compared to existing state-of-the-art method, SegFormer, it reduces 64% FLOPs while maintaining the accuracy to a large extent on two commonly-used benchmarks. The proposed SMALNet can be used in various infrared based vision perception systems with limited hardware resources.
•The inner hollow size is introduced to control deformation and mechanical properties.•The large inner hollow size significantly improves the elastic modulus.•The elastically isotropic hollow-strut ...lattice structures are obtained.•The optimization framework considers the volume fraction and inner hollow size.•The framework improves structure's stiffness compared with traditional approaches.
Lattice structures with hollow struts exhibit superior mechanical properties as compared to solid ones. In this study, we introduce a new type of body-centered cubic (BCC) lattice, consisting of hollow prismatic struts with mechanical properties defined by an inner hollow parameter. The mechanical properties and deformation behavior of the BCC lattice structures with different inner hollow parameters are investigated under periodic boundary conditions. It is shown that the elastic modulus of the hollow-strut BCC lattice structure improves significantly by 598%-1460% and their deformation mechanism gradually changes from bending-dominated to stretching-dominated, when the inner hollow size increases. In contrast, there are little influences on shear deformation. Interestingly, tunable Poisson's ratio and isotropic elasticity can be achieved by adjusting the inner hollow size. In addition, the BCC lattice structures with different inner hollow parameters are fabricated by digital light processing for compression tests, and the experimental results are in good agreement with the simulation with relative errors of less than 14.6%. Finally, a high-fidelity interpolation model is employed to describe the effective elastic matrix of lattice structures, and a new optimization framework is proposed to simultaneously optimize the distribution of the volume fraction and inner hollow size of hollow-strut lattice structures. This proposed approach significantly improves the stiffness (compliance decreased by 15.8% to 53.1%) of the cantilever beam as compared to traditional optimal designs, demonstrating the potential application of the proposed approach in lightweight designs.
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•Novel TPMS-based strut-shell interpenetrating lattice metamaterials are designed.•Strut-shell interpenetrating lattices have superior specific surface area.•Fusion proportion achieves tunable ...mechanical properties and deformation behavior.•Strut-shell interpenetrating lattices can effectively avoid sharp stress drop.•Interpenetrating lattices have superior densification and energy absorption.
Mechanical metamaterials (MMs) are artificially designed structures with superior properties that originate from unit cells. Compared with the widely studied single-morphology MMs, multi-morphology interpenetrating MMs offer, by the virtue of their fused lattice characteristics, the potential for customizable mechanical properties and new application fields. Inspired by the fact that the isosurface of triply periodic minimal surfaces (TPMS) can divide a lattice into two independent regions, this paper proposes a novel TPMS-based strut-shell interpenetrating (TSSI) lattice metamaterial. This study demonstrates that the TSSI lattice has a larger specific surface area than traditional TPMS lattices. Compared with the volume fraction, the fusion proportion parameter is not only more conducive to effectively adjusting the mechanical properties in a wide range and controlling the anisotropy of the lattice metamaterials to achieve elastic isotropy but significantly changes the dominant mechanism of deformation under uniaxial and shear loads. Moreover, the TSSI lattice metamaterial can avoid sharp stress drops due to the mutual support and wrapping of the internal interpenetrating lattices after failure, resulting in a more stable energy absorption efficiency and a maximum increase in energy absorption of 74%. This work provides new opportunities to design lightweight components with a wide range of customizable mechanical properties and superior energy absorption.
In this paper, we propose a new multiscale topology optimization method to design the solid–lattice–void hybrid structures. A novel ordered solid–lattice–void interpolation model has been developed ...that realizes smooth transition across the solid, lattice, and void phases, and very importantly, this interpolation model coordinates well between the multiple variables describing the lattice configuration and the relative density variable indicating the solid, lattice, or void status. Specifically, a multi-variable lattice resulted from topology optimization is accepted as the candidate lattice and its effective elastic properties are established through regressive fitting. Then, the ordered solid–lattice–void interpolation formula is developed, which unifies the multi-phase interpolation that allows exceeding the lattice upper/lower limit to reach the solid/void status for the elements. Finally, the multiscale topology optimization algorithm is formulated and implemented for solid–lattice–void hybrid structure design. Numerical examples are studied which demonstrate significant structural performance improvement compared with pure lattice-infilled structures. Finally, additive manufacturing and mechanical tests are conducted to validate the effectiveness of the proposed method.
•Propose a new multiscale topology optimization method to design the solid–lattice–void hybrid structures.•Develop a novel ordered solid–lattice–void interpolation model that realizes smooth transition across the multiphase.•Develop a multi-variable lattice resulted from topology optimization as the candidate lattice.•Demonstrate significant performance improvement by involving the solid and void phases in lattice structure optimization.
Due to the increasing number of internal combustion engine vehicles, fossil fuel sources have decreased drastically in the last century. In addition, the concerns about global warming caused by ...vehicle emissions have led automotive manufacturers to search for new alternatives to transport. Quadricycles have started to be seen as future transport vehicles due to their smaller design and lower energy consumption when compared to conventional vehicles. Furthermore, they are also considered to prevent increasing traffic jams in metropolitan areas. The lightweight design of a quadricycle is crucial since its weight would affect energy consumption. On the other hand, because of their minimalistic design, crashworthiness is another factor that must be considered in the structural design of quadricycles for the safety of occupants in case of a collision. Composites are one of the most promising materials for manufacturing lightweight structures due to having a high strength-to-weight ratio compared to conventional metals. In this study, different body designs and optimizations of quadricycles are introduced. Comparisons are made between conventional metals and composite materials used in quadricycles in terms of weight and stiffness.
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