Crush Initiator Research Articles

Application of neural networks specific forms for estimation of crushing signal parameters of multilevel structural absorbers implemented in passive safety research

In case of classic thin-walled energy absorber the energy dissipation is not sufficiently controlled during a collision. A significant part of the columns does not participate in plastic deformation sufficiently. This is due to a lack of proper crush initiators for the formation of subsequent joints. The research problem of the article is to presents a method of applying artificial intelligence methods for determining the optimal parameters of crush initiators, in order to make proper use of plastic deformation zones and improve the efficiency of energy absorption. The methodology is based on the artificial neural network models made possible to select the best and optimal design parameters of multilevel crush initiators. The results of numerical tests were verified on the test bench. The values of all crashworthiness indicators improved, the PCF has been reduced up to 30% from for certain geometric parameters of the multilevel crush initiator.

Analytical Prediction of Crushing Thin-Walled Square Tube with Static Axial Loads Using Elliptical Holes as Crush Initiators

In the structure of passenger vehicles there are components that absorb the impact load, which components are commonly thin-walled square tube. The design of the impact energy absorber model can be carry-out by experiment, simulation, and analysis. In the design of this impact energy absorbing component, an elliptical hole was used as a crush initiator to reduce peak loads and set the start of the bending pattern. Analytical predictions were made to reduce costs and speed up time to obtain mean load and peak loads values from the same shape model. In this study, a thin-walled square tubes model is used with an elliptical hole that have ratio of horizontal axis and vertical axis is from 3:7 until 7:3. The result of this study showed that the prediction of the peak load and average load by analytical means has a good conformity with the simulation. Keywords: Impact energy absorber, analytical, square tube, elliptical hole.

An investigation into the crashworthiness criteria of a top-hat structure with a dent-type crush initiator through numerical analysis

Ensuring the safety of passengers and the battery compartment in electric vehicles during frontal collisions is of utmost importance. This research aims to enhance the design of the top-hat structure used in car front rails by incorporating a crush initiator as the weakest section. The addition of a crush initiator optimizes the crashworthiness criteria by reducing peak force and increasing energy absorption. Numerical simulations were conducted using ABAQUS to validate the findings and compared against experimental results from references. The results demonstrate that the development of a top-hat structure with a dent-type crush initiator led to 27.5% decrease in peak force and 18.75% increase in energy absorption. The improvements in peak force and energy absorption could reduce the impact force and allow the crumple zone to completely absorb the kinetic energy during a collision, positively affecting the safety of passengers and battery compartments in electric vehicles

Multiobjective optimization of dimension and position of elliptical crush initiator on crashworthiness performance of square tube using response surface methodology

In this study, the crashworthiness performance of a thin-walled square steel-tube structure with an elliptical crush initiator under impact loading was investigated. The effect of the height, width, and distance of the crush initiator from the top of the tube on the crashworthiness performance was analyzed using several numerical simulations using ABAQUS Explicit. The response surface methodology was used to predict the crashworthiness performance indices, and optimization was performed to determine the optimal dimensions and position of the crush initiator. The optimization was aimed at minimizing the peak force (PF) while maximizing the mean crushing force (MCF), crush force efficiency (CFE), and specific energy absorption (SEA). The result was an elliptical crush initiator with a height of 15 mm, width of 24.784 mm, and distance of 15.08 mm. Validation was performed to verify these results. The optimal crush initiator effect resulted in a 10.12% decrease in the peak force, 13.67% increase in the crush force efficiency, and 2.23% increase in the mean crushing force. However, a slight decrease of 0.82% in specific energy absorption was observed.

Crush Behavior of Aluminum/Composite Hybrid Tubes under Quasi-Static Loading

This paper presents a review of the crush behavior of aluminum/composite hybrid tubes which are produced by wrapping one or more composite layers on aluminum tubes. It also provides new experimental data on the effect of crush initiators on the crush behavior of aluminum/composite hybrid tubes. It is shown that the crush initiator can influence both the failure mode as well as the energy absorption of all three types of tubes.

Modeling of Crashworthiness Criteria based on Variation of Hole as Crush Initiator in Thin-Walled Square

Crashworthiness is the ability to protect its occupant by absorbing the energy of impact during a collision. A crush initiator is one way to increase crashworthiness criteria at collision. The most widely applied crush initiator applications are holes, wall thickness reduction, grooves, notch, bead and corrugated. This study discussed making a functional model from the crashworthiness criteria which is known by CFE and SEA. Variable used variations of the crush initiator in the form of circular holes with different rotation angles and diameters. The rotation angle referred to in this study was 2 holes which are rotated based on the midpoint of the hole distance to the radial axis of the hole. The crush initiator was placed in a square column at each side with steel material. Besides, the wall thickness variable was added which can increase the energy absorption during a collision. The method used numerical simulation and experimental dynamic loading. The numerical simulation used the explicit finite element method by using ESI PAM-Crash. Both methods used the drop test model by using impact transferability. Impact transferability was rigid which was used to transfer impact loading during impact conditions. Experimental was used to validate the function model which was obtained through the least square method with sampling from numerical simulations. The results showed the same patterns produced by the functional and experimental models using the Taguchi method (L9) with 3 runs. The maximum of this pattern is 23% for CFE and 17% for SEA. Meanwhile, the average error of the S/N ratio shows 8.77% for CFE and 2.16% for SEA. This model function could be used by a crashworthy designer to estimate the value of CFE and SEA.

Study on the Effect of Geometrical Parameters of a Hexagonal Trigger on Energy Absorber Performance Using ANN.

Thin-walled structures are commonly used as energy absorbers in motor vehicles. Their function is to protect the structural components of vehicles and to absorb energy completely during collisions up to 20 km/h. This paper focuses on maintaining crush axiality during research. To verify the numerical analyses, physical specimens were made and then subjected to dynamic crushing. Force and shortening values as well as high-speed camera images were used for data analysis. Through time-lapse shots, plastic deformation within the crush initiator was observed. Such detailed analysis allowed the determination of the influence of hexagonal triggers in the form of notches on the post-buckling progressive analysis. In this paper, neural networks were used to examine the importance of each variable. Data from numerical analyses were used for this purpose. Based on the analyses performed, the effects of both the width and height of the triggers on the crush load efficiency (CLE) and total efficiency (TE) ratios can be seen. The width of the crush initiator has the greatest influence on Crash-box performance. Nevertheless, increasing both the height and the width of the initiator can result in crush non-axiality and underperformance of the energy absorber.

The Influence of Different Length Aluminum Foam Filling on Mechanical Behavior of a Square Thin-Walled Column

The demand for lightweight, strong structural profiles is currently high in the transport industry, mechanical engineering, and construction. Therefore, it is important to evaluate their properties, especially mechanical properties. The main objective of this paper is to determine energy absorption coefficients and evaluate the crush resistance of thin-walled aluminum profiles using numerical simulation and empirical verification. This paper presents the compression results of testing of thin-walled aluminum profiles filled with a porous material (cast aluminum foam). The numerical analysis was conducted using the software Abaqus/CAE. Aluminum material data were obtained from a static tensile test performed on a Shimadzu machine. The experiment was performed on an Instron CEAST 9450HES dynamic hammer. Profiles with three shapes of crush initiators filled with aluminum foam measuring 40 mm–200 mm in 20 mm increments were numerically tested. A sample with a concave initiator filled with foams of 40 mm, 60 mm, 80 mm, and 120 mm in length was used to verify the numerical analyses. Energy absorption coefficients were determined from the analyses. The results of both analyses were tabulated to show the percentage differences. The study showed an increase in the Crush Load Efficiency (CLE) index by up to 33% for samples with the same crush initiator. In addition, it was noted that the use of porous fill does not increase the value of initiating Peak Crushing Force (PCF), which indicates the generation of much smaller overloads dangerous for vehicle passengers.

An increase in crashworthiness capability using pyramid arrangement of the crush initiator

Collisions on vehicles could cause injury to passengers such as being thrown from a passenger room. To prevent this, a vehicle structure was not too strong which called by crashworthiness criteria through maximum impact force. This study was conducted to determine the smallest structural strength through maximum impact force in a square column with 0.8 mm in thickness. The column was given holes with 3 mm in diameter as crush initiators. The hole was arranged in pyramid pattern with different level and begun with 1 hole in the square column. The research used the quasi-static concept experimentally with 30 mm/min in movement speed of actuator. The machine used Universal Testing Machine (UTM) with 200 kN in capacities. The result showed that the pyramid arrangement with the highest level had the greatest maximum impact force 22.124 kN. Comparison of differences between the highest levels with the lowest levels reached 4.86%. While the difference between the highest level with a square column with 1 hole was 14.24%. So that the more holes arranged in a pyramid would reduce the maximum impact force during a collision.

Crashworthiness topology optimization of thin-walled square tubes, using modified Bidirectional Evolutionary Structural Optimization approach

Abstract In this study, topology optimization of a thin-walled square tube subjected to an axial crushing load was carried out to enhance its crashworthiness performance, utilizing the modified Bidirectional Evolutionary Structural Optimization (BESO) procedure. In this way, by systematic searching, topology optimization finds the best material layout for the structure to satisfy the objective function. In each iteration, a new pattern of material-void through the tube walls can trigger various folding mechanisms. Thus, the energy absorption history trend might not be smooth and the ultimate pattern proposed by the algorithm is less likely to be the optimal one. With an emphasis on the BESO hypothesis regarding direct removal and addition of elements, the modified BESO algorithm excavated the optimal design in two steps. First, material-void patterns were produced, considering specific energy absorption as the element efficiency criterion. Then, the pattern with the least material usage which satisfies an energy absorption constraint was selected as the optimal design. Such an optimum layout also boosts the tube performance respecting peak crushing force, since the embedded voids through the structure serve as a crush initiator. The optimization code was developed in MATLAB, which was automatically integrated with ABAQUS software performing the nonlinear crushing analysis. To validate the finite element model, an experimental investigation was carried out on a simple square tube. Having performed the topology optimization and some fine-tuning process, the topologically optimized tube was constructed and experimentally tested. Results showed 16.21% weight reduction enriched with 36.57% enhancement in the peak crushing force by sacrificing less than 3.5% energy absorption, which represents substantial improvements from a crashworthiness viewpoint. The obtained interesting results showed the high potential of the BESO algorithm for the design of thin-walled structures under large deformation and out-of-plane buckling.

Theoretical Prediction of Dynamic Axial Crushing on a Square Tube with Eight Holes Used as a Crush Initiator

Theoretical Prediction of Dynamic Axial Crushing on a Square Tube with Eight Holes Used as a Crush Initiator

ANALISIS DAMPAK GAYA TUMBUKAN MELALUI PERUBAHAN BENTUK SEGI CRUSH INITIATOR PADA STRUKTUR TAILOR-WELDED BLANK

Tailor-welded blank (TWB) structure is one of the vehicle component models used in vehicle parts. In addition, these structures can be used in crashworthiess technology which can reduce injuries during a collision.. The structure of a vehicle that has greater strength can cause passengers to be thrown from the passenger compartment. This paper discusses the effect of faceted holes such as square, hexagonal and octagonal as crush initiator mounted on TWB which results in a maximum impact force (Fmax). The smallest maximum impact force is the criteria achieved from this study. The method used experimental quasi-static loading of the actuator speed of 0.5 mm/s to achieve 9.5 mm of deformation. TWB was made from plate formation with a process of stamping to spot weld. The result showed that the maximum impact force has an increase directly proportional to the addition of the shape of the crush initiator in the amount of 14.633 kN to 18.705 kN. From these results, it can be seen a square hole as best design in obtaining the smallest maximum impact force.

Design Optimization of Crashworthiness in Square Tube as Thin Walled Structure With Variations of Crush Initiator: Stripe-Parallelogram-Trigon

Crashworthiness is an ability of a vehicle structure in order to reduce injury when occurred in collision. Crashworthiness criteria are peak force (Fmax), specific energy absorption (SEA), and crush force efficiency (CFE). The part of structure of vehicle in crashworthiness is front rail which is generally tube as thin walled structure. The aim was to know the best design in thin walled square tube as specimen by variance of crush initiator which arranged holes 3 mm of diameter in shaping stripe with 4 holes, then added graded holes in parallelogram to trigon. This research used compression experiment method under quasi static loading with 30 mm/minute of actuator velocity. Optimum design was done by using Multi Criteria Decision Making (MCDM) with Simple Additive Weighting (SAW) modelling. This research presents that specimen with trigon of crush initiator is the best design with 0.98 of decision score in which crashworthiness criteria for peak force, specific energy absorption and crush force efficiency are 19193.81 N; 5100.93 J/kg; and 46.44%.

Experimental and Numerical Study - Effects of Crush Initiators under Quasi-Static Axial Load of Thin Wall Square Tube

Crush initiators are used to improve the energy absorption and reduce the peak crush load at the time of the initial accident. This study aims to determine the effect of crush initiators on thin-walled square tube of local product which is applied on the front rail Electric Cars University of Indonesia under the quasi static axial loads. Crush initiator was designed in the form of two parallel holes with a diameter of 6.5 mm at a distance of 20 mm from the surface of the tube on each side. Analysis was done by comparing the experimental result with the result of numerical analysis by using finite element method of ANSYS. The result showed the significant effect from the crush initiators on decreasing the peak crush load and increasing the energy absorption and showed a similar pattern between the experimental and numerical computation result.

Crush Characteristics and Energy Absorption of Thin-Walled Tubes with Through-Hole Crush Initiators

An experimental investigation was conducted to compare the crush characteristics and energy absorption capacity of circular and square tubes with located through-hole crush initiator. Circular through-holes were fabricated at three different configurations based on location into steel tubes which had a length of 200 mm. Furthermore, two different side configurations along the tube were considered for introducing the crush initiators. The results found that adding crush initiator onto the tubes were effectively reduced the initial peak force of a thin-walled circular and square tubes under axial quasi-static loading. The peak crush force was reduced within a range 3-10% and 5-16% for circular and square tubes respectively when compared with corresponding tubes without crush initiator. Moreover, the energy absorption capacity of the tubes was independent with the incorporation of through-hole crush initiators. However, the energy absorption of circular and square tubes were slightly decreases when compared with the tubes fabricated four sided crush initiation and tubes without crush initiator. Overall, the effect of location and number of crush initiation proved significantly influences the initial peak forces while maintain the energy absorbed.

Axial crush simulation of braided carbon tubes using MAT58 in LS-DYNA

This paper examines a composite damage constitutive model, MAT58, in LS-DYNA and its application for use in braided composite tube axial crush simulations. The constitutive response of MAT58 was investigated using single element simulations. It was found that MAT58 reproduced the softening behavior of the braided composite under monotonic compressive loading, but failed in subsequent unloading and tensile loading cycles. A deficiency in the damage law in MAT58 was identified. Unloading and reloading a volume of material that had suffered some degree of damage was a part of the process with the progressing of crush zone during the axial crush of composite tubes. Consequently, this deficiency hinders the success of MAT58 in such applications. In tri-axial braided composite tube axial crush simulations, although the predicted initial peak forces were within 20% of the experimental values, the predictions for the specific energy absorption (SEA) values were consistently low, particularly for tubes without a plug as crush initiator. These discrepancies are attributable to the deficiency in the damage law in MAT58.

Crush Initiators for Increased Energy Absorption in Composite Sandwich Structures

Sandwich composites loaded in edgewise compression often display low energy absorbing failures due to facesheet debonding and/or buckling-type failure modes. Although crush initiators have been used to trigger progressive crushing in monolithic composites, little research has been performed to investigate the use of crush initiators with sandwich composites. In this investigation, fixture-based crush initiators were evaluated for producing progressive crushing failures and high levels of energy absorption under dynamic edgewise compression loading. Four different sandwich configurations were investigated, fabricated using woven or random mat carbon/epoxy facesheets with foam or balsa wood cores. Results show that the effectiveness of crush initiators is highly dependant upon both the facesheet and core materials used in the sandwich construction. Additionally, the initiation of progressive crushing of a sandwich composite appears to be dependent on the stiffness and strength properties of both the facesheets and core as well as the strength of the facesheet/core interfaces. These findings suggest that a sandwich composite may be designed for enhanced energy absorption through the proper selection of facesheet and core materials and geometries such that high-energy absorbing failure progressions are produced, especially with the application of a crush initiator.

A vehicle front frame crash design optimization using hole-type and dent-type crush initiator

The hole-type crush initiators according to various ratios of thickness to width ( t / b ) were studied. And the approximate equation to quickly predict the optimum size of the crush initiator by impact velocity for each ratio of thickness to width was introduced. Also, the simple rectangular and circular dent-type crush initiators of a front frame with non-uniform closed-hat section in a vehicle were studied for frontal crashworthiness according to various ratios of thickness to width ( t / b ) . The optimum size and dent depth of a crush initiator, whose location is decided by the homogenization method, were studied by using design of experiment and response surface method. Design analysis results of the dent-type crush initiators were compared with those of the hole-type crush initiator of the same size as the dent-type crush initiators. The rectangular dent-type crush initiator absorbed more crash energy than the circular dent-type crush initiator. Dynamic mean crushing loads of a rectangular dent-type crush initiator of size equal to that of the hole-type crush initiator designed by the homogenization method were similar to those of the hole-type crush initiator. The trend curve of the optimum size rectangular dent-type crush initiator design is similar with the trend curve of hole-type crush initiator design. Therefore, the approximate equation used to predict the optimum size of the hole-type crush initiator can be applied to find the optimum size of the rectangular dent-type crush initiator.

The crush behavior of glass fiber reinforced plastic sections

The crush response of glass fiber reinforced plastic tubes, of cylindrical, square and rectangular section, made from unidirectional tape with various alternating 0° and 90° lay-ups, and also of small samples cut from these tubes, was studied with particular reference to the effects of the geometry of the crush trigger initiator. It was found that the propagation of delamination cracks contributed little to the energy absorption capacity, most of the crush resistance being derived from the development of kink bands in the fiber structure. The crush resistance of square tubes with thinner walls was largely provided by the corners. As the wall thickness increased, the planar portions contributed more to the crush resistance. Approximate estimates of the specific energy may be made from crush tests of simple flat sections. The trigger geometry alters the energy absorption capacity by the extent to which it generates deformation flaws which can then propagate within the wall structure. Softer crush anvils reduce the effectiveness of the trigger crush initiator and can lead to global failure of the section, rather than to stable, progressive crush.