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Friction stir welding (FSW), a solid-state joining process, is commonly used to join Aluminum alloys in aerospace, marine, car industry, and numerous industrial applications. Lightweight materials are commonly used in the transport industry to minimize component weight, and thin-walled structures are increasingly being used as energy-absorbing components in the industry. Even though FSW of plates is well established, FSW of pipe is still at the laboratory level. In this work, FSW for 6063 aluminum alloy pipe has been experimented through a novel procedure and it’s flexural and crashworthiness studies are carried out. The attempt of FSW is performed with a unique welding fixture mounted on a traditional milling machine. The crashworthiness test is conducted to analyze the ability of the structure to nullify the life loss during impact and the crash force efficiency of the pipe is identified. It is further analyzed for the flexural test to identify the bending load of welded aluminum alloy pipes. This study also exposes the basic understanding of the FSW procedure and its metallurgical implications of a friction stir welded pipe.

Generally, developing crashworthy components necessitates the use of a specific structural design that facilitates efficient crushing deformation to absorb accident impact energy. The modern techniques for reducing the intensity of the impact are formed from techniques of recent advancement. The metallic foam and honeycomb structures are both capable of absorbing a significant amount of specific energy. Both structural arrangements, however, have inherent limitations: honeycomb structures are unidirectional, while metallic foam structures have extremely random 3D cell configurations. While additive manufacturing has given rise to the creation of complex geometry that aids in the production of crash-worthy components, such as lattice structures, it has also pioneered the way for the development of parts with even more complex geometries. Lattice systems are intended to absorb crash energy while allowing for both three-dimensional and normal structural configurations. Since lattice systems have a high potential for use in crash effect structures, they can be extremely useful in energy management of crash effect structures. Based on the literature, an attempt has been made to develop a new form of unit cells since they are the most significant feature of the lattice structure in terms of energy absorption. Nine distinct types of unit cells are developed and analyzed. The planned unit cells are loaded in a single direction. The study determined the energy-absorbing characteristics of nine different types of unit cells, including deformation, peak force, energy absorption, and crash force strength. The maximum specific energy absorption (SEA) was calculated for nine different unit cell configurations using the software “ANSYS/EXPLICIT.” The “Type-6” unit cell is discovered to be well suited for crashworthy components.

To better evaluate the crash performance of the guardrail and reduce the number of actual vehicle crash tests, this paper uses mechanical analysis and finite element simulation technology to evaluate the typical movable guardrail and optimize the structure. It’s of great significance for improving the crashworthiness of this type of guardrail and enhancing its safety performance. Firstly, the vehicle-barrier mechanical model was established to calculate the vehicle collision force on the barrier. Secondly, the collision force model was used to calculate the collision of a 10-ton truck, and a finite element model of a typical movable barrier was established for a collision simulation. Finally, the wall thickness and column spacing were optimized according to the results. The simulation results show that the maximum lateral dynamic deformation of the barrier was 1,818 mm, which agrees with the actual vehicle test results (1,600 mm). When the wall thickness of the barrier increases by 2 mm, the maximum lateral dynamic deformation was 1,419 mm; When the spacing of strengthened columns was reduced to 15 m, the deformation was 1,364 mm; After optimization, the deformation was reduced by more than 20%, and the crashworthiness of barrier was improved obviously.

Uniform lattices composed of one type of lattice structure repeated periodically have been extensively investigated in literature for their mechanical and physical properties. Their promising properties, which include a desirable combination of high strength, stiffness and toughness, suggest that hybrid structures made of two or more lattice types can exhibit even more advantageous and desired properties. In this work, the mechanical properties of hybrid cellular structures designed using implicit functions are investigated both experimentally and numerically. Two proposed samples are investigated comprised of a Gyroid and a Diamond unit cells hybridised linearly and radially. First, a finite element computational model was utilised in LS-DYNA to capture the mechanical properties of the additively manufactured constituent lattices (i.e., Gyroid and Diamond) made of stainless steel 316L and tested under dynamic and quasi-static loading conditions. The model was validated for three different relative densities. Then, the validated computational model was then tested to predict the mechanical behaviour of the proposed hybrid lattices. Finally, the proposed hybrid lattices were fabricated and mechanically tested to obtain their mechanical properties. A good agreement between experimental and computational results was achieved. The validated computational models will be used to evaluate other designs of TPMS lattices and their crashworthiness performance for protective equipment applications.

For structural bending crashworthiness, previous studies mostly focused on thin-walled tubes with multi-cell cross-sections, while the double-tube configuration was seldom studied. In this paper, the bending crashworthiness of thin-walled tubes with multi-cell and double-tube configurations was compared based on three-point bending tests conducted using the ABAQUS/Explicit code. The numerical results reveal that the reinforcements significantly improve the bending crashworthiness beyond the conventional empty tube according to the two indicators: specific energy absorption (SEA) and crash load efficiency (CLE). For the ratio of cross-sectional width to wall thickness b/t = 100, the double-tube configuration has a similar bending crashworthiness performance to the multi-cell configuration. The asymmetric multi-cell configurations are found to demonstrate more excellent SEA performance than their symmetric counterparts in most cases. For the case b/t = 50, the double-tube configuration significantly prevails over the multi-cell configuration.

Tubular thin-walled structure has attracted more and more attention because of its light weight and energy absorption characteristic, and has been widely applied to the fields of aerospace and auto...

Many hierarchical structures have good mechanical properties, which can better improve the energy absorption characteristics and achieve lightweight. This article proposed a novel circumferential s...

This paper presents an experimental investigation about the effect of the hole on the crushing force of thin tubes with the square cross-section under axial impact with a high strain rate. To this ...

This work overviews the axial crushing behaviour of tube in absorbing kinetic energy produced due to impact collision. Key insights on crash mechanics of crumple zone are provided to understand the...

The continuing efforts of automotive technology aim to deliver even greater safety benefits and reduce the weight of a vehicle. Thin-walled beams (TWB) are widely used as strengtheners or energy absorbers in vehicle bodies due to their lightweight and excellent energy absorption capacity. Thus, researchers are interested in the collapse behaviour and mechanical properties of thin-walled beams under static and dynamic loadings. Circular TWB is commonly used in vehicle side doors. In the event of a side collision, this beam deforms and absorbs the greatest amount of impact energy. In this study, the energy absorption capability and crashworthiness of polygonal cross-section TWBs subjected to lateral impact was investigated using numerical simulations. Polygonal TWB ranging from square to dodecagon, as well as circular cross section, were selected for this study. Energy absorption (EA), specific energy absorption (SEA) and crash force efficiency (CFE) crashworthiness indicators are employed to evaluate the bending collapse performance. Because TWB thickness and weight have a greater impact on bending performance, they were kept constant across all polygons. In ABAQUS explicit dynamic software, finite element simulations are performed, and plastic hinges and flattening patterns of all polygons are examined. The results show that heptagon, octagon, and nonagon cross-section TWB perform better in crashworthiness than square and circular TWB.

A novel structure with enhanced energy absorption is proposed by introducing thin-walled tube as the inner liner tube of the cylindrical structures with negative Poisson’s ratio (C-NPR). The energy absorption performances of C-NPR structure with inner tube (C-NPR-IT) are compared to other configurations like the single NPR structure, single thin-walled tube, and C-NPR structure with outer tube (C-NPR-OT) to show its superiority. It is found that the interaction between the NPR structure and inner tube in C-NPR-IT can be enhanced. Then, the parametric analysis of the geometric parameters on the crashworthiness performance of C-NPR-IT structures are performed with finite element method. To achieve the best configuration, the surrogate modeling technique and the multi-objective particle swarm optimization (MOPSO) algorithm are employed to optimize the C-NPR-IT structures. The results show that the optimized structure improves the specific energy absorption (SEA) from 3.97 to 10.26 kJ/kg by almost 2.5× by controlling peak crushing force (PCF) less than 80 kN. Therefore, the C-NPR-IT structure has an application prospective in the energy absorber.

Porous aluminum (Al) composites are lightweight and high-strength materials composing of Al as a matrix material with some strengthening reinforcements and pore-forming agents that result in the formation of new material with superior physical properties and energy absorption capacities. This work gives an overview of the porous Al-foams developed thus far, including the foaming agents and space holders, their properties, production techniques, and applications. First, it deliberates the foaming agents and space holders responsible for the foaming and formation of pores in the composites followed by the mechanical properties of the foams. Al has huge potential for applications that require lightweight, high-strength, and high-energy absorption capacity materials, especially in structural construction and automobile manufacturing. Although Al-foams have been successfully used in automobiles for crashworthiness, lightweight structure, and other functional applications, the development of Al foams with enhanced characteristics and properties has limitations. This review discusses various reinforcements used for improving the characteristics of Al-foams. This review also provides an overview of various commercial foams and their contribution to several applications. Finally, it attempts to reveal impediments in foam production with suggested solutions for overcoming the problems in this area.

Thin-walled tubes are widely used as energy absorbers due to their high crashworthiness performance. This study aims to evaluate the effect of plastic forming history carried out for thickness optimization on crashworthiness performance of thin-walled square tube (TWST). Within the scope of the study, a series of numerical analyses were conducted for the TWST using a commercial finite element (FE) software. In order to determine individual effect of optimization, FG thickness of TWST was first obtained using LS-OPT software. Later, thickness gradient was achieved by performing rolling process to consider individual plastic forming effect Afterwards, deep drawing process was carried out to shape TWST by considering springback and trimming effects. Finally, crash responses were obtained under axial high velocity impact loading to determine the coupled effect of optimization and plastic forming on the crashworthiness performance of the TWST. It was determined that the coupled effect, which takes plastic forming and optimization effects into account, reduced the peak crush force of the TWST by 24% and increased the absorbed energy value by 39%. The results obtained from this study showed that coupled effect of optimization and plastic forming processes has significant effect on the crashworthiness performance of the TWST and otherwise either overestimated or underestimated results are obtained.

The fascia of a car is a part that is responsible for absorbing the impact during a frontal or rear collision involving vehicles. Energy absorption is a critical parameter in determining the fascia’s efficiency. Twill weave Kenaf and Plain weave Kevlar polymer composites were used to study low-velocity impact behavior. CATIA V5 R20 software was used to create a 3-D solid model of fascia, which was then imported into the Hypermesh environment and simulated using LS-DYNA. In Economic Commission for Europe (ECE) United Nations Agreement, regulations were used to simulate the process for the study. Under the maximum deflection, the intensity was investigated in elastic mode using energy absorption and impact behaviour. The collision test was conducted at a constant low velocity of 4 km/hr., for five different laminate sequences L1 to L5, with fabric stacking as the predominant parameter. Further, L3, L4 and L5 hybrid laminates were compared with pure Kevlar (L1) and Kenaf (L2) laminates. The results were interpreted by using LS-PREPOST to analyze the energy absorption characteristics during crash for different materials. It was observed that the maximum internal energy uptake was recorded by L5 based on the stress distribution model. When compared to L3 and L4, L5 accounted for a 48 percent and a 24 percent increase in energy absorption, respectively, which clearly indicates that hybridization, stacking pattern adopted and the orientation of fabric have greatly influenced the strength of the laminate. In addition to these, the automobile industry can benefit from the use of renewable and environment-friendly materials considered for this study.

TPMS (triply periodic minimal surface) sheet structure consists of a spatially continuous surface, which forms a periodic porous structure, and has outstanding mechanical performance and ultralight...

A new excellent energy absorption structure named as leaf vein branched circular tubes (LVBCT) is proposed based on lotus leaf vein branched structure. The crashworthiness of LVBCT under lateral lo...

The lotus root multi-cellular structure is a novel filling structure with good energy-absorbing properties. In this paper, the relationship between cell geometry and mechanical properties of lotus ...

The composite material in energy absorption tube application have gained a tremendous function as sacrificial structure device in automotive, marine, and aerospace engineering. Due to capabilities of composite material in reinforcement structure, many researchers have explored to tailor the composite material properties to withstand into impact load condition. This present study of filament wound kenaf/glass hybrid composite tube was fabricated with three different configurations of hybrid kenaf/glass fibre placement to obtained high capabilities of crashworthiness properties under intermediate-velocity impact load condition. Therefore, this present study has identified the hybridization technique of kenaf/glass fibre which tailored with various intraply stacking sequences parameter of filament winding technique to achieve better impact crashworthiness characteristic when compared with single synthetic glass composite fibre material. The arrangement of hybrid fibres in stacking sequence parameter has found that the hybrid specimen with high kenaf fibre fraction mass have enhanced 68 % of energy absorbing value and the failure mode behaviour was more stable compare to synthetic glass composite tube specimen.

An energy absorbing tube combining multi-corner and multi-cell configurations was designed in this study. Machine learning was adopted to predict and optimize the crashworthiness of the proposed tu...

The changes in energy-absorption and deformation characteristics of thin-walled E-glass fiber reinforced composite conical frusta upon introduction cutouts were studied through quasi-static axial c...

The bending crashworthiness performance of thin-walled structures is affected by several factors such as the end-clamping constraints. The end-clamping configuration should be carefully investigated since it is an important part of the real working condition of a structure under bending loading. End-clamping fixtures (pads) can be used intentionally as complementary energy dissipating mechanisms to trigger new plastic deformation. The present article explores the use of pads to improve the crashworthiness of square tubes under lateral loads. For this purpose, internal, external, and combined pads were located at the profile ends which were subjected to a modified three-point bending test using finite element simulations. The effect of assembly force (fN) and pad length (lp) on the energy absorption was investigated. The structures were made of aluminum 6063-T5 and modeled with elasto-plastic properties considering ductile and shear damage criteria with evolution. Additionally, the numerical results were validated by an experimental three-point bending test on a square profile with constrained and free ends. Our results for a structure with end-clamping fixtures show an improvement of crashworthiness performance in a range from 42.38 – 57.89% relative to a structure with free-ends. The best crush force efficiency (CFE) of 0.78 was obtained when external pads were implemented. Moreover, the importance of fN on the end-clamping pads was noticed since CFE is increased by 9.30% when a normalized force of 0.109 is applied. The importance of pad length was also demonstrated. An improvement of 69.38% in CFE was achieved when a normalized length $$ {\overline{L}}_p $$ = 0.138 was implemented. Finally, with the findings of our work, a design of end-clamping fixtures for an automobile’s side-door impact beam is presented and analyzed.

Bioinspired structure/material has attracted attentions in engineering fields. In this article, a novel sandwich cylinder inspired by shore horsetail is proposed by introducing the double-arrowed a...

Offshore structures are exposed to risks of vessel collisions and impacts from dropped objects. Tubular members are extensively used in offshore construction, and thus, there is scope to investigate their crashworthiness behaviour. Aluminium, glass fibre reinforced polymer (GFRP) and hybrid aluminium/GFRP circular tube specimens were fabricated and then tested under quasi-static and dynamic axial loading conditions. Two hybrid configurations were examined: external and internal layers from respectively aluminium and GFRP, and vice versa. The material impregnated with epoxy resin woven glass fabric was allowed to cure attached to the aluminium layer to ensure interlayer bonding. The quasi-static and dynamic tests were conducted using respectively a universal testing machine at a prescribed crosshead speed of 10 mm/min, and a 78 kg drop hammer released from 2.5 m. The non-hybrid configurations (aluminium and GFRP specimens) outperformed their hybrid counterparts in terms of crashworthiness characteristics.

Thin-walled tubes are widely used as energy absorption devices because of their excellent crashworthiness. In this paper, a novel tubular configuration with a double-layer sinusoidal corrugated sec...

New products based on a structure that represents a combination of known elements in a higher quality set, as well as products that refer to new shapes, new curves, new surfaces can be obtained logically - analytically - deductively or by methods specific to the optimal calculation. The present paper focuses on the method of analyzing tridimensional morphology, some possible solutions being evaluated on value criteria. Of course, these methods can be applied in the field of engineering with very good results. The focus of this study is to obtain new thin walled tubular structures - such as car crash members - which in the case of axial shock loads have a higher predictable behavior compared to those already used in various technical fields. Following the study, it can be said that depending on the amount of absorbed energy in the case of axial collisions and the absorption of kinetic energy developed at the time of impact, the optimal crashworthiness solution could be tubular structures with a circular support base and rectangular deformable area for impact.

Induced structure has been widely used in thin-walled structures to reduce the initial peak crash force (PCF) and improve the crashworthiness. In this paper, the perforated aluminum-carbon fiber re...

Multi-wall profile as one of the most widely approaches can enhance the crashworthiness properties in thin-walled tubular structures. In actual application process as energy absorbers, there may be...

During a side impact accident of an automobile, the automobile threshold plays an important role in maintaining the living space of passengers, and thus the crashworthiness design of thresholds may...

This work investigates the crashworthiness of jute fiber mat reinforced epoxy composite circular tubes by introducing holes around the tube circumference. The composite tubes were tested under quas...

The present work deals with the crashworthiness behaviour of high-density polyethylene (HDPE) composite against aluminium alloy (Al5022). For the composite reinforcement purpose, 20 wt. % of kenaf ...

A new type of axially varying thickness lateral corrugated tube (AVTLCT) is proposed and optimized, and the energy absorption and multi-objective optimization of the two AVTLCTs with the number of ...

This paper proposes a new type of energy absorber with combined shrinking circular tubes for a high-speed train. An impact experiment is conducted to investigate the dynamic crushing performance of this energy absorber with combined shrinking circular tubes. The results show that the combined tubes experience steady dynamic shrinking deformation. Finite element (FE) models of the energy absorber are then developed, and the dynamic crushing forces are in good agreement with the impact test. A theoretical solution for the dynamic shrinking crushing load is derived. Based on the validated FE models, the effects of the friction coefficient, wall thickness and die radius on the dynamic crushing force and energy absorption are investigated. An increase in the wall thickness leads to a substantial growth in the maximum crushing force (Fmax) and specific energy absorption (SEA), but the growth rate of Fmax is much larger than that of the SEA as the wall thickness increases. In addition, comparing theoretical and FE results demonstrates that predictions of the dynamic steady-state forces for the combined shrinking circular tubes with different friction coefficients, wall thicknesses (t) and die radius (Rdie) are satisfactory. Finally, to improve the crashworthiness of the expanding circular tubes, Sobol’ sensitivity analysis is employed to analyze the effects of the design parameters (t and Rdie) on the objective responses (SEA and Fmax) using the Kriging model. A Pareto front of double optimization objective SEA and Fmax was obtained after being optimized by multiobjective particle swarm optimization (MOPSO). The results show that SEA and Fmax are positively correlated, and a balance between the SEA and Fmax was obtained at optimal point C (SEA = 13.09 kJ/kg, Fmax = 581.11 kN).

A novel two-dimensional (2D) mechanical metamaterial with highly programmable mechanical response under compressive load is presented in this paper by introducing hierarchical rotating structures, in which flexible structures are used to replace the rigid part in conventional rotating rigid structures. Multi-step deformation pathways and negative Poisson’s ratio were observed in in situ compression experiments and finite element simulations, suggesting that the mechanical behavior of the hierarchical metastructure is highly ordered and can be programmed by constraining angles of the proposed metamaterial. This work offers new insights to create mechanical metamaterial using hierarchical rotating structures for flexible devices and crashworthiness applications.

Tape-based discontinuous composite is a relatively new type of composite material that offers improved mechanical properties for similar process-ability compared to Sheet Moulding Compound or Bulk ...

This article aims to propose a kind of internally reinforced square tube based on triply periodic minimal surfaces (TPMSs), which can be obtained by computer-assisted techniques and additive manufacturing. To achieve this goal, a finite element simulation model is exploited to simulate the collision situation of reinforced thin-walled tubes. The design of reinforced tubes can be formulated into a multiparameter and multiobjective optimization problem, which can be solved using the well-known non-linear programming by quadratic Lagrangian (NLPQL) optimization method. Three types of TPMS-based tubes and two multicell tubes are compared under the same conditions to show the effectiveness of our method. Through the methods mentioned above, TPMS-reinforced tubes are found to be superior in crashworthiness. This means that the safety performance of the automobiles with lighter weight can be effectively improved. The optimal parameters of three types of TPMS-reinforced tubes under different conditions were obtained, providing the foundations and references for subsequent related studies. In addition, TPMS is first explored in the design of crashworthiness for automobiles in this article. Due to the controllability and implicit functional expression of TPMSs, TPMS-reinforced tubes can be easily controlled and optimized. Meanwhile, it is easy to manufacture them by three-dimensional printing technologies.

Aiming at reducing the energy absorption of the hydrogen cylinder for fuel cell vehicles in collision, which may lead to fierce explosion, this paper introduces an energy-absorbing protective shell combining with negative Poisson’s ratio (NPR) structure to the hydrogen cylinder. It adopts three honeycomb structures of the same mass and three kinds of aluminum alloy to determine the optimal structure and material scheme of the protective shell. Besides, sensitivity analysis is selected to screen the design parameters of the optimal structure scheme. Based on this, the overall mass of the designed protective shell, the specific energy absorption of NPR structure, the maximum impact force of rigid wall, and the maximum stress of the liner are taken to establish the optimization mathematical model. Furthermore, adaptive mutation genetic algorithm (AMGA), non-dominated sorting genetic algorithm-ii (NSGA-II), and adaptive simulated annealing algorithm (ASA) are exerted as the optimization algorithms separately to conduct optimization design and a comparison is made between the optimization results. The results show that the optimized energy-absorbing protective shell has better crashworthiness and energy absorption effect, which can effectively improve the collision safety of the hydrogen cylinder. It provides a new idea for the protection design of hydrogen storage system in fuel cells in the future.

In this paper, the crashworthiness characteristics of tapered structures with the uniform cells in cross-section subjected to oblique impacts are theoretically and numerically investigated. Benefit...

This study focuses on the axial and oblique low-velocity impact response of thin-walled aluminium conical frusta with circular cutouts at two different locations through experimental and finite ele...

In the present research, the crushing response and crashworthiness characteristics of aluminum circular tubes with and without vertical corrugations were studied. In this regard, crashworthiness ch...

Strong, lightweight structures are increasingly in demand for various engineering applications. Here we present a method to produce a lightweight lattice composite tube with hexagonal unit cells using a high production rate, textile-based method. A weft knitting process was employed for the first time to produce lattice preforms made of a common high-performance E-glass yarn. The lattice preforms were impregnated with epoxy resin to create lattice composite tubes of various sizes. The crashworthiness performance of the as-fabricated lattice composite tubes was evaluated experimentally and numerically in quasi-static axial compression tests. Based on the findings and the results of comparisons made with expanded metal tubes, the proposed lattice composite system exhibited comparable energy absorption properties. Finite element simulations provided insight into the failure mechanism of the proposed structure for predicting the energy absorption behavior of the composite lattice. The simulations revealed that further improvement was possible if global buckling could be controlled, which was carried out in the current study via polyurethane foam injection into the tube and using a concentric placement of multiple tubes of various sizes. Overall, the proposed lightweight, knitted lattice composite tube showed enhanced performance in its strength.

Thin-walled tubular structures are widely employed in applications. The current study proposes an innovative cost-saving and eco-friendly thin-walled cylinder concept using recycled beverage cans. ...

Filling structures with aluminium honeycomb is a typical method for increasing the energy absorption (EA) characteristics of thin-walled beams. This paper puts forward the new outstanding energy ab...

In recent years, light-weight nano composite materials have been progressively employed in the aviation, defense, naval and automotive manufacturing applications owing to their outstanding mechanical and crashworthiness characteristics. In this regard, nano composite cylindrical tubes could be significantly utilized as energy absorbing elements for dissipating the impact energy during vehicle collisions. The present research study aimed to examine the lateral crashworthiness response of Multi-Walled Carbon Nano Tubes (MWCNT) filled epoxy composite (basalt fabric and glass fabric) tubes of three different inner diameters using quasi-static crushing experiments. Crushing profiles and crush force–deformation curves of all the recommended typical tube samples are computed and discussed elaborately. The results obtained revealed that better crashworthiness characteristics of MWCNT reinforced epoxy composite tubes with a larger diameter, were owing to more promising crushing modes occurring during lateral compression. It is also found that the lateral crashworthiness response of the MWCNT filled glass fabric epoxy composite tubes was marginally superior to that of the MWCNT filled basalt fabric epoxy composite tubes. However, both the recommended composite cylindrical tubes with nano-fillers might be employed as energy dissipating elements in modern vehicles.