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Shear strength evaluation in composites is still a problem that has not been fully solved. Dynamic shear strength evaluation is even more complicated. In present work, failure theories are used to determine the range of fiber orientations in which the evaluation of shear strength is feasible. The symmetrical laminate is used to eliminate coupled shear strain to improve measurement accuracy. Three different fiber orientation laminates are chosen for quasi-static tension test. And a combination of experimental and numerical method is carried out for high strain rate tests. The results show that the fiber orientation of ± 15° is suitable for evaluating the dynamic shear strength of CFRP (Carbon Fiber Reinforced Polymer). This study is of great significance to dynamic shear strength evaluation method of continuous fiber reinforced composites considering strain rate effect. [ABSTRACT FROM AUTHOR]

Square-circle hybrid section (SCHS) tubes under axial loading which combine the advantage of square tubes and circular tubes are investigated. Firstly, effective finite element models of SCHS tubes are established to study the crashworthiness characteristics. Through a series of finite element models, the influence of the geometry on the behaviour of crashworthiness is studied, including relative size of square and circular sections in SCHS tubes and the position of connecting plates. The results show that compared with corresponding traditional multi-cell tubes, SCHS tubes improve the performance in energy absorption, with a maximum increase of 40.49%, while reducing peak force and improving crushing load efficiency. Moreover, the deformation of elements constituting the SCHS tube is analysed, and deformation of arc-plate elements could be classified into three typical modes. According to the observed deformation modes, the theoretical model is proposed to predict the mean crushing force of SCHS tubes. The theoretical results show that it is in good agreement with the numerical results. [ABSTRACT FROM AUTHOR]

This article deals with initial material selection and design method of long fibre-reinforced thermoplastic (LFT) based on impact resistance requirements. In this study, effects of material properties and impact condition, including total fibre thickness, fibre aspect ratio and impactor diameter, on the minimum penetration energy of LFT plates are analysed based on experiments and validated numerical models. Mathematical expression is established between them. Applicability of the original model for LFT plate with different fibre aspect ratios subjected to different impactors is discussed. The minimum penetration energy is used as the bridge between energy absorption characteristics and material parameters, impact condition. Finally, an updated theoretical model for energy absorption analysis is proposed. We conclude that the updated semi-empirical model is a valuable tool for a first stage material selection and design. [ABSTRACT FROM AUTHOR]

This article presents a multi-component topology optimization method for thin-walled structures, which can be applied to two-dimensional plate components and three-dimensional tube components. Based on the theory of multi-component topology optimization for stamped sheet metal assemblies, an accurate calculation method for the Young's modulus of joint elements is provided. To avoid the discontinuous derivative and improve the optimization efficiency, a non-zero gradient-based material interpolation scheme with penalization is constructed. The cost of die-set materials can be controlled effectively by the maximum size of components. Several topology designs based on minimized compliance confirm the effectiveness of the proposed method. The topology solutions illustrate that the proposed method can realize the structural design of thin-walled structures which can meet the die-set material cost requirement. [ABSTRACT FROM AUTHOR]

This paper presents a design method for manufacturable casting parts based on topology optimization of structural assemblies, which considers the geometry requirement and the manufacturing constraint of die-set material cost. The problem formulation follows the previous work presented in multi-component topology optimization for stamped sheet metal assemblies (MTO-S). Based on the vector method combined with Heaviside function, the moldability constraints for casting parts is formulated. As the base structure of component is easily misidentified as an undercut structure by the moldability constraints in the structural assemblies, the component baseline is proposed to realize the automatic filtering of the "fake" undercut structures which can be extended to the parting line to obtain the form of two-mold design. Several numerical examples on compliance minimization of single-mold and two-mold casting parts are conducted to verify the validity of the proposed method. The optimized results show that there is no interior void for each component and the component manufacturability has been improved obviously. The setting of minimum-area bounding box (MABB) area constraint limits and the number of components will have a significant effect on the performance of the optimized structure. Users can achieve the desirable solution based on their actual demand by making trade-offs between the structural performance and manufacturing cost. [ABSTRACT FROM AUTHOR]

Based on the theoretical crashworthiness model of variable thickness rectangular section tubes, this article simplified the super-folding element to analyze the energy absorption characteristics of variable thickness 12 right-angles section (VTTRS) tubes during axial crushing. To discuss the deformation mode of VTTRS tubes, a series of finite element models were built based on the verified finite element model of variable thickness rectangle section tubes. Then, the deformation of VTTRS tubes was studied to obtain the structures deforming in stable mode which have a great performance in energy absorption. Meanwhile, a theoretical solution of the mean crushing force for VTTRS tubes was proposed and verified by establishing three groups of finite element models with different thicknesses and thickness gradients. Finally, a prediction for crash box was presented and the results showed the great potential of VTTRS tubes in energy absorption and explained the important role played by the theoretical model for vehicle during concept design stage. [ABSTRACT FROM AUTHOR]

Electric vehicles have become the main trend of the future development of the automotive industry due to their advantages such as energy conservation and environmental protection, strong acceleration capability, and low noise. This paper uses a volume-produced fuel passenger vehicle P5 as a prototype. Based on the given driving mode and traction battery pack layout of a battery electric vehicle (BEV) EP5, considering the static stiffness and crashworthiness simultaneously, the equivalent static load (ESL) method is used to perform multi-load topology optimization on the body-in-white (BIW) of the BEV. Then the load paths of EP5 are proposed. The front-end structures of the vehicle body are redesigned by using topology optimization and size optimization, which improve crashworthiness and fully tap the lightweight potential of EP5. [ABSTRACT FROM AUTHOR]

The newly revised GB 13057-2014 'The strength of the seats and their anchorages of passenger vehicles' replaces the static test with a dynamic test, which puts forward higher requirements on seat safety. Considering safety and lightweight design, the LFT (Long glass Fiber reinforced Thermoplastic) is used to replace the original steel seat back frame. Combined with energy absorption model and topology optimisation, the force transmission path and detail structure design under both the forward loading and rearward loading conditions are carried out. In order to analyse the occupant protection performance, numerical models of composite seat and HybridIII dummy are established, and the safety and lightweight effect of LFT seat back frame are optimised and verified. [ABSTRACT FROM AUTHOR]

The newly revised GB 13057-2014 put forward high requirements for the dynamic occupant protection of passenger car seats. Due to the high density of steel, there is currently not much space for lightweight through structure improvement. In this paper, the quasi-static and dynamic mechanical properties of CFRP and corresponding simulations are used to study the mechanical behaviour of CFRP and verify the accuracy of simulation. It is now applied to the composite seat backplane structure design, and combined with the CFRP moulding process and the energy absorption characteristics of the car seat backplane to initially design the CFRP seat backplane material and structure. At the same time, considering the designability of the material itself, the ply optimisation technology under multi-condition is used to design the material and structure of the CFRP passenger car seat backplane. The new CFRP passenger car seat achieves significant weight reduction while meeting regulatory requirements. [ABSTRACT FROM AUTHOR]

The newly revised national standard GB 13057-2014 'The strength of the seats and their anchorages of passenger vehicles' puts forward higher requirements for occupant protection of passenger car seats in the dynamic test. Simply improving safety performance may increase seat weight. Considering the dual requirements of safety performance and light weight, this article adopted the topology optimisation method and took into account the strength requirements of multiple loading conditions: forward loading and rearward loading, and finally optimised the structure of seat backrest frame. By changing the weight ratio of loading conditions and the topological mass fraction, the optimal material distribution and force transmission paths of seat backrest frame were optimised. At the same time, considering the ergonomics and the strength of the seat fixing points, the structure of seat backrest frame was fully optimised. On the premise of improving the safety performance of the seats (occupant protection), significant weight reduction was also achieved. [ABSTRACT FROM AUTHOR]

The front-end structure crashworthiness design during the conceptual design phase of automobile can shorten production cycle and has a great significance to improve safety. This paper proposes a three-stage target decomposition method to design crash pulse and manage the crash energy absorption of front-end structure of automobile. In this method, the theoretical optimal solution of the Equivalent Dual-trapezia Wave (EDTW) is calculated by the overall layout parameters of automobile and safety requirements of occupant. The optimal EDTW, as the target crash pulse, is decomposed to segments based on the reserved longitudinal crush space and the lateral energy absorption ratio of the front-end substructure. In addition, simple mathematical and mechanical principles are applied to calculate the performance objectives of key energy absorption substructures. Finally, an empirical application of M6 model is conduct to verify the validity of EDTW optimal solution and the realizability of target decomposition. The result shows that this proposed method is effective for the conceptual design of new cars and model change of existing cars. The design process does not rely on large computing software and empirical data and the design result has a guiding role in CAE analysis of automobile safety. [ABSTRACT FROM AUTHOR]