Quasi-Static Biaxial Plastic Buckling of Tubular Structures Used as an Energy Absorber

2006 ◽  
Vol 74 (4) ◽  
pp. 628-635 ◽  
Author(s):  
R. Baleh ◽  
A. Abdul-Latif
Keyword(s):  
Mild Steel ◽  
Energy Absorption ◽  
Strength Properties ◽  
Absorption Capacity ◽  
Loading Path ◽  
Geometrical Parameters ◽  
Tubular Structures ◽  
Plastic Buckling ◽  
Applied Loading ◽  
Plastic Strength

The aim of this experimental study is to improve the energy absorption capacity of tubular metallic structures during their plastic buckling by increasing the strength properties of materials. Based on a novel idea, a change in the plastic strength of materials could be predictable through the loading path complexity concept. An original experimental device, which represents a patent issue, is developed. From a uniaxial loading, a biaxial (combined compression–torsion) loading path is generated by means of this device. Tests are carried out to investigate the biaxial plastic buckling behavior of several tubular structures made from copper, aluminum, and mild steel. The effects of the loading path complexity, the geometrical parameters of the structures, and loading rates (notably the tangential one) on the plastic flow mechanism, the mean collapse load, and the energy absorbed are carefully analyzed. The results related to the copper and aluminum metals show that the plastic strength properties of the tubes crushed biaxially change with the torsional component rate. This emphasizes that the energy absorption improves with increasing the applied loading complexity. However, the energy absorbed data for the mild steel tubular structures do not demonstrate the same sensitivity to the quasi-static loading path complexity.

Dynamic Biaxial Plastic Buckling of Circular Shells

2008 ◽  
Vol 75 (3) ◽  
Author(s):  
A. Abdul-Latif ◽  
R. Baleh
Keyword(s):  
Mild Steel ◽  
Energy Absorption ◽  
Biaxial Loading ◽  
Steel Structures ◽  
Strength Properties ◽  
Local Deformation ◽  
Loading Path ◽  
Geometrical Parameters ◽  
Plastic Buckling ◽  
Copper Aluminum

Of particular interest is the experimental study of the complex dynamic plastic buckling of circular metallic shells and their energy absorption capacity. Initially proposed by Baleh and Abdul-Latif (2006), “Quasi-Stalic Biaxial Plastic Buckling of Tubular Structures used as an Energy Absorber,” ASME J. Appl. Mech., 74, pp. 638–635, the novel idea, which aims to enhance the strength properties of materials, is extended for studying the biaxial plastic dynamic buckling behavior of circular shells. It can be assumed that changes in local deformation mechanisms, which reflect this enhancement in the strength properties, are mainly governed by the loading path complexity. The question of whether the performance of dynamic axially crushed tubes could be further improved by using the developed device (the absorption par compression-torsion plastique (ACTP)) generating a biaxial loading path (combined compression and torsion) from a uniaxial loading. A key point emerging from this study is that the structure impact response (i.e., the plastic flow mechanism and the absorbed energy) is influenced by the loading rate coupled with the biaxial loading complexity. In this study, three different metallic circular shells made from copper, aluminum, and mild steel, having distinct geometrical parameters, are extensively investigated. The obtained results show that the higher the biaxial loading complexity provided by the ACTP applied, the greater the energy absorbed by the copper, aluminum, and mild-steel structures. Thus, it is easy to demonstrate that the enhancement in the energy absorption, notably in the case of aluminum, is higher than 150%, in favor of the most complicated loading path (i.e., biaxial 45deg case) compared to the classical uniaxial case. Moreover, the deformation mode for the tested materials is slightly sensitive to the torsion amplitude in dynamic loading, contrary to the quasistatic one.

Dynamic crashing behavior of thin-walled conical tubular structures with nonlinearly-graded diameters

2018 ◽  
Vol 233 (7) ◽  
pp. 2456-2466 ◽  
Author(s):  
Fengxiang Xu ◽  
Suo Zhang ◽  
Kunying Wu
Keyword(s):  
Energy Absorption ◽  
Absorption Capacity ◽  
Geometrical Parameters ◽  
Tubular Structures ◽  
Power Law Distribution ◽  
Thin Walled Structures ◽  
Conical Structure ◽  
Thin Walled ◽  
Energy Absorbing ◽  
Effective Design

Thin-walled structures with graded property have been paid more attention in recent years due to their significant balance between lightweight and crashworthiness. However, few studies have been focused on energy absorption capacity of thin-walled conical tubes with graded diameters. In this paper, the thin-walled conical aluminum tubes with nonlinearly-graded diameters are introduced and their corresponding crashing characteristics are performed. The diameters are assumed to nonlinearly vary according to a power-law distribution function primarily determined by a graded exponent n. It is found that the total weight of thin-walled conical tubes decreases with the increasing of the gradient exponent. The energy-absorbed performances such as specific energy absorption, initial peak crashing force, and mean crashing force of those graded tubular structures are numerically analyzed. And then the effects of various geometric parameters such as the gradient exponent, deformation distance, and diameter range on crashing behaviors are further evaluated. It is observed that those parameters especially the gradient exponent has significantly obvious effects on crashworthiness of the proposed nonlinearly graded tubes. It is also noted that the straight conical structure with gradient n = 1.0 may not show the best energy absorption characteristics compared with other gradients. The work could provide valuable information for effective design of thin-walled energy-absorbing structures with variable geometrical parameters.

scholarly journals Fracture toughness of concrete with basalt fiber

2019 ◽  
Vol 265 ◽  
pp. 01008 ◽  
Author(s):  
Marta Kosior-Kazberuk ◽  
Julita Krassowska
Keyword(s):  
Energy Absorption ◽  
Basalt Fiber ◽  
Strength Properties ◽  
Critical Stress Intensity Factor ◽  
Absorption Capacity ◽  
Basalt Fibers ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
New Methods ◽  
Crack Tip Opening

The analysis of fracture mechanics parameters of concrete with new types of fibers is essential for the dissemination of their application and development of new methods of structural design.Fracture mechanics parameters are widely used to analyze the material behaviour and also in the design process of selected structures. The paper reports the results of an experimental programme focused on the effect of non-metallic (basalt) fibers on the fracture properties of concrete investigated in Mode I conditions. The changes in concrete properties were analysed on the basis of the critical stress intensity factor KIc, the critical value of crack tip opening displacement (CTODc) and the fracture energy GF. The addition of the basalt fibers had a slight effect on the strength properties of concrete but, at the same time, it had a significant influence on the fracture parameters by the modification of pre-cracking and particularly post-cracking behaviour of the concrete. Results of measuring the toughness and energy-absorption characteristics showed that the specimens reinforced with basalt fibers acquired a great ductile behaviour and energy absorption capacity, compared to ordinary concrete specimens.

The Energy Absorption Characteristics of Square Mild Steel Tubes With Multiple Induced Circular Hole Discontinuities—Part I: Experiments

2009 ◽  
Vol 76 (4) ◽  
Author(s):  
S. B. Bodlani ◽  
S. Chung Kim Yuen ◽  
G. N. Nurick
Keyword(s):  
Mild Steel ◽  
Energy Absorption ◽  
Circular Hole ◽  
Progressive Collapse ◽  
Experimental Tests ◽  
Absorption Capacity ◽  
Peak Force ◽  
Steel Tubes ◽  
Initial Peak ◽  
Absorption Characteristics

This two-part article reports the results of experimental and numerical works conducted on the energy absorption characteristics of thin-walled square tubes with multiple circular hole discontinuities. Part I presents the experimental tests in which dynamic and quasistatic axial crushings are performed. The mild steel tubes are 350 mm in length, 50 mm wide, and 1.5 mm thick. Circular hole discontinuities, 17 mm in diameter, are laterally drilled on two or all four opposing walls of the tube to form opposing hole pairs. The total number of holes varies from 2 to 10. The results indicate that the introduction of holes decreases the initial peak force but an increase in the number of holes beyond 2 holes per side does not further significantly decrease the initial peak force. The findings show that strategic positioning of holes triggers progressive collapse hence improving energy absorption. The results also indicate that the presence of holes may at times disrupt the formation of lobes thus compromising the energy absorption capacity of the tube. In Part II, the finite element package ABAQUS/EXPLICIT version 6.4–6 is used to model the dynamic axial crushing of the tubes and to investigate the action of the holes during dynamic loading at an impact velocity of 8 m/s.

Functionally Graded Cellular Core Cross Tube: Finite Element Study

2019 ◽  
Author(s):  
Sean Jenson ◽  
Eboreime Ohioma ◽  
Muhammad Ali ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Fuel Efficiency ◽  
Compressive Loading ◽  
Absorption Capacity ◽  
Functionally Graded ◽  
Thin Wall ◽  
Tubular Structures ◽  
Energy Absorption Capacity ◽  
Wall Structures

Abstract Thin wall structures are primarily deployed in automotive chassis to increase the energy absorption capacity of the automobiles in the event of an accident. Researchers have delved into developing lighter structures for improving automobiles’ fuel efficiency with a challenge of maintaining or preferably exceeding the energy absorption properties of the structure. In this study, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. The crushing response of cellular core cross tube was numerically studied using ABAQUS/Explicit module. The characteristics such as deformation or collapsing modes, crushing/ reactive force, locking strain, energy curves, and specific energy absorbed were studied. The cellular core cross tube shows significant potential for reducing the weight of automobile structure while giving positive indication towards enhancing the specific energy absorption capacity.

scholarly journals Cork Core Sandwich Plates for Blast Protection

2020 ◽  
Vol 10 (15) ◽  
pp. 5180
Author(s):  
Jesús Pernas-Sánchez ◽  
Jose A. Artero-Guerrero ◽  
David Varas ◽  
Filipe Teixeira-Dias
Keyword(s):  
Energy Absorption ◽  
Mechanical Response ◽  
Numerical Models ◽  
Areal Density ◽  
Absorption Capacity ◽  
Geometrical Parameters ◽  
Sandwich Plates ◽  
Arbitrary Lagrangian Eulerian ◽  
Reference Case ◽  
Blast Protection

A numerical model is developed and validated to analyse the performance of aluminium skin and agglomerated cork core sandwich plates subjected to blast loads. Two numerical approaches are used and thoroughly compared to generate the blast loading: an Arbitrary-Lagrangian–Eulerian approach and the Load Blast Enhanced method. Both of the models are validated by comparing the numerical results with experimental observations. A detailed analysis of the sandwich behaviour is done for both approaches showing small differences regarding the mechanical response of the sandwich structure. The results obtained from the numerical models uncover the specific energy absorption mechanisms happening within the sandwich plate components. A new core topology is proposed, based on these results, which maximises the energy absorption capacity of the plate, keeping the areal density unchanged. A wavy agglomerated cork core is proposed and the effects of different geometrical parameters on the energy absorption are thoroughly analysed and discussed. The proposed optimised plate configuration shows an increase in the total absorbed energy of close to 40% relative to a reference case with the same areal density. The adopted optimisation methodology can be applied to alternative configurations to increase the performance of sandwich structures under blast events.

Study of Energy Absorption Characteristics of Square Tube With Composite Cellular Core

2018 ◽  
Author(s):  
Muhammad Ali ◽  
Eboreime Ohioma ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Compressive Loading ◽  
Absorption Capacity ◽  
Structural Members ◽  
Tubular Structures ◽  
Tube Material ◽  
Energy Absorption Capacity ◽  
Core Tube ◽  
Energy Absorbing ◽  
Deformation Modes

Square tubes are primarily used in automotive structures to absorb energy in the event of an accident. The energy absorption capacity of these structural members depends on several parameters such as tube material, wall thickness, axial length, deformation modes, locking strain, crushing stress, etc. In this paper, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. Here, the crushing response of composite cellular core tube was numerically studied using ABAQUS/Explicit module. The energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, crushing stroke, and energy curves were discussed. The composite cellular core tube shows promise for improving the crashworthiness of automobiles.

scholarly journals Mechanisms of energy absorption in special devices for use in earthquake resistant structures

1972 ◽  
Vol 5 (3) ◽  
pp. 63-88 ◽  
Author(s):  
J. M. Kelly ◽  
R. I. Skinner ◽  
A. J. Heine
Keyword(s):  
Reinforced Concrete ◽  
Kinetic Energy ◽  
Mild Steel ◽  
Energy Absorption ◽  
Earthquake Engineering ◽  
Absorption Capacity ◽  
Concrete Frames ◽  
Energy Absorption Capacity ◽  
Structural Applications ◽  
Energy Absorbing

A structure designed to resist earthquake attack must have a capacity to dissipate kinetic energy induced by the ground motion. In most structures this energy absorption is developed in the vicinity of beam to column connections. Recent research has shown that connections are not reliable when subject to cyclic loading, such as results from earthquake attack. Connections in steel frames deteriorate due to local instabilities in adjacent flanges, and in reinforced concrete frames alternating shear
loads produce diagonal tension and bond failures which progressively reduce the strength of the connection. Much work in building research and earthquake engineering in laboratories throughout the world is directed toward increasing the reliability and energy absorption capacity of structural connections. In this paper an alternative approach to this problem is described. This approach is to separate the load carrying function of the structure from the energy absorbing function and to ask if special devices could be incorporated into the structure with the sole purpose of absorbing the kinetic energy generated in the structure by earthquake attack. To determine whether such devices are feasible a study has been undertaken of three essentially different mechanisms of energy absorption. These mechanisms all utilized the plastic deformation of mild steel. They included the rolling of strips, torsion of square and rectangular bars,
 and the flexure of short thick beams. These mechanisms were selected for intensive study since they were basic to three different types of device each of which was designed for a separate mode of operation in a structural system. The characteristics of these mechanisms which were of primary importance in this study were the load displacement relations, the energy absorption capacity and the fatigue resistance. This information was obtained with a view to the development of devices for specific structural applications. This report describes the tests used to explore the basic mechanisms and the data obtained. It also include s a brief description of tests on scale models of a device which was designed to be located in the piers of a reinforced concrete railway bridge. It has been shown by the tests that the plastic torsion of mild steel is an extremely efficient mechanism for the absorption of energy. It was found that at plastic strains in the range 3% to 12% it was possible to develop energy dissipation of the order of 2000-7500 lb in/in3 per cycle (14-50 x 106 N/M2 per cycle) with lifetimes within the range of 1000 to 100 cycles. It was also shown that the mode of failure in torsion is an extremely favourable one for use in an energy absorbing device in that it took the form of a gradual decay. The other two mechanisms studied were both less efficient and less reliable than torsion and had capacities of 500-2000 lb in/in3 per cycle (3.5 - 14 x 106 N/M2 per cycle) and life times of around 200 to 20 cycles. Nevertheless they lend themselves to more compact devices than does the torsional mechanism and furthermore the devices may be located in regions in a structure where they are readily accessible for replacement after attack.

Uniaxial crushing of constrained tubes

2001 ◽  
Vol 215 (3) ◽  
pp. 353-364 ◽  
Author(s):  
A A Singace ◽  
H El-Sobky
Keyword(s):  
Mild Steel ◽  
Aluminium Alloy ◽  
Energy Absorption ◽  
Radial Direction ◽  
Absorption Capacity ◽  
Displacement Curve ◽  
Energy Absorption Capacity ◽  
Axial Crushing ◽  
The Mean ◽  
Load Displacement

By changing the end constraints, the behaviour of mild steel and aluminium alloy tubes of relatively low D/ t ratio, subjected to an axial crushing load, is studied. Many combinations of end constraints were produced by radially constraining one or both ends of the loaded tube outwards, inwards or in both directions. Partially constrained mild steel and aluminium tubes are found to collapse into either a pure concertina mode or a pure diamond mode, depending on the ratio D/ t and the material characteristics. Mixed concertina-diamond modes would generally result by radially constraining the tube at both ends. Constraining the tube radially outwards at one end does not significantly affect the load-displacement characteristics and the mode of collapse. However, constraining the tube radially inwards produces a different mode than that observed under outward, inward or combined outward/inward constraint. New modes of collapse have been observed under different combinations of outward and inward constraints at both ends. Fully constraining the tubes in the radial direction results in the removal of the initial overshoot in the load-displacement curve, which is responsible for the overestimation of the mean crushing load and the energy absorption capacity of tubular elements. The mode of collapse and the energy absorbed could be controlled with the proper choice of the end constraints.

Response of Filled Thin-Walled Square Tubes to Axial Impact Load

2014 ◽  
Vol 566 ◽  
pp. 586-592
Author(s):  
Steeve Chung Kim Yuen ◽  
Gerald Nurick ◽  
Sylvester Piu ◽  
Gadija Ebrahim
Keyword(s):  
Energy Absorption ◽  
High Speed ◽  
Impact Load ◽  
Absorption Capacity ◽  
Tubular Structures ◽  
Energy Absorption Capacity ◽  
Axial Impact ◽  
Foam Filled ◽  
Thin Walled ◽  
Initial Peak

This paper presents the results of an investigation into the response of thin-walled square (60x60 mm and 76x76 mm) tubes made from mild steel filled with four different fillers; aluminium foam (Cymat 7%), two types of aluminium honeycomb and polyurethane foam to quasi-static and dynamic axial impact load. The energy absorption characteristics of the foam-filled tubes are compared to that of a hollow tube, through efficiency calculations. The tubular structures are subjected to axial impact load generated by drop masses of 320 kg and 390 kg released from a height ranging between 2.1 m to 4.1 m. Footage from a high speed camera is used to determine the average crush forces exerted by each specimen. The results show that the fillers have insignificant effects on the initial peak forces based on the quasi-static results but increase the overall mean crushed force. The findings also indicate that the fillers affect at times the size of the lobe formed thus compromising the energy absorption capacity of the tube.

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