ESDA2010-24782 EXPERIMENTAL STUDY OF CORRUGATED TUBES UNDER LATERAL LOADING

ABSTRACT The protection of structures under impact loading often necessitates the need for energy absorbers; devices designed to absorb the impact energy in a controlled manner and hence, protect the structure under consideration. Thinwalled tubes are widely used as energy absorbers in various vehicles and moving parts. The objective of the present study is to investigate the energy absorption characteristic of tubes with corrugations in different geometries, in lateral direction. In order to produce corrugations, an innovative solution is introduced. Corrugations can be very easily generated on the surface of cylindrical aluminum tubes by stamping method. Corrugations with different wavelengths and amplitudes can be produced by this method. Experimental tests are conducted to study the effect of changing corrugation geometry (type and amplitude). Quasi-static tests are carried out whose results for lateral compression show that tubes with corrugation have a higher mean crushing force and this force is directly proportional to number of corrugations and their amplitude. Moreover, it is observed that corrugated tubes can absorb approximately four times more energy than tubes without corrugations, in the same size and weight. Finally, considering the experimental tests, corrugated tubes are shown to be more effective in lateral direction as an energy absorber, and they also exhibit desirable force-deflection responses which are important in the design of energy absorbing devices

A novel axially half corrugated thin-walled tube for energy absorption under Axial loading

In this paper, tubes with different axial corrugations were studied under axial loading. Accordingly, a new axially half-corrugated thin-walled tube was developed to improve the energy absorption characteristics. The forming process of the corrugations on the tubes has also been described. Comprehensive experimental and numerical analysis have been conducted in order to investigate the effects of various geometrical parameters on crushing behavior of the structure. It has been shown that by the use of the new axially half corrugated tube, there is much more efficient crushing via a more uniform force-displacement result as well as a considerable improvement in other crashworthiness characteristics. Subsequently, a numerical study has been conducted on the same tubes to both have the numerical results validated and assure the repeatability and reliability of the experimental results. An efficient model in axial loading has been obtained which is offering a perfect concertina form. The obtained model deforms through an inversion mode causing an extra frictional force between the inverted part and the tube itself, resulting in a considerable increase in SEA, mean force, and consequently CFE. - 2019 Elsevier LtdScopu

Magneto-electro-elastic vibration analysis of modified couple stress-based three-layered micro rectangular plates exposed to multi-physical fields considering the flexoelectricity effects

In this paper, based on the CPT, motion equations for a sandwich plate containing a core and two integrated face-sheets have derived. The structure rests on the Visco-Pasternak foundation, which includes normal and shear modules. The piezo-magnetic core is made of CoFe2O4 and also is subjected to 3D magnetic potential. Two face sheets at top and bottom of the core are under electrical fields. Also, in order to obtain more accuracy, the effect of flexoelectricity has took into account at face sheets’ relations in this work. Flexoelectricity is a property of all insulators whereby they polarize when subject to an inhomogeneous deformation. This property plays a crucial role in small-scale rather than macro scale. Employing CPT, Hamilton’s principle, flexoelectricity considerations, the governing equations are derived and then solved analytically. By present work a detailed numerical study is obtained based on Piezoelectricity, Flexoelectricity and modified couple stress theories to indicate the significant effect of length scale parameter, shear correction factor, aspect and thickness ratios and boundary conditions on natural frequency of sandwich plates. Also, the figures show that there is an excellent agreement between present study and previous researches. These finding can be used for automotive industries, aircrafts, marine vessels and building industries

Buckling and crushing behavior of foam-core hybrid composite sandwich columns under quasi-static edgewise compression

Buckling and crushing behavior of foam-core hybrid composite sandwich columns under edgewise compressive load is dealt in this study. Composite laminates with different stacking sequence configurations made of glass and Dyneema-woven fabrics and AL 2024-T3 sheets were used in combination of polyvinyl chloride foam core to manufacture the specimens. Effects of face sheet thickness and stacking sequence configuration, slenderness ratio, boundary conditions, and sandwich reinforcement with through-thickness resin pins on the buckling and crushing behavior of the specimens were investigated. The results revealed that using the resin pins changes the unstable Euler buckling mode to a more stable progressive end-crushing and significantly increases the buckling load, specific buckling load, and energy absorption capability, which are highly favorable. Also, the results showed that in the specimens with fiber metal laminates, the major failure modes are face sheet-core debonding and face sheet delamination. However, based on the results, specimen with hybrid face sheets made from Dyneema fabrics and aluminum plates has the highest buckling load as well as the highest specific buckling load. Also, a specific fixture was designed to laterally clamp the sandwich column which causes a reduction in the probability of specimen end-crushing and significantly increases the buckling load. - The Author(s) 2019.The publication of this article was funded by the Qatar National Library.Scopu

Buckling and crushing behavior of foam-core hybrid composite sandwich columns under quasi-static edgewise compression

Buckling and crushing behavior of foam-core hybrid composite sandwich columns under edgewise compressive load is dealt in this study. Composite laminates with different stacking sequence configurations made of glass and Dyneema-woven fabrics and AL 2024-T3 sheets were used in combination of polyvinyl chloride foam core to manufacture the specimens. Effects of face sheet thickness and stacking sequence configuration, slenderness ratio, boundary conditions, and sandwich reinforcement with through-thickness resin pins on the buckling and crushing behavior of the specimens were investigated. The results revealed that using the resin pins changes the unstable Euler buckling mode to a more stable progressive end-crushing and significantly increases the buckling load, specific buckling load, and energy absorption capability, which are highly favorable. Also, the results showed that in the specimens with fiber metal laminates, the major failure modes are face sheet-core debonding and face sheet delamination. However, based on the results, specimen with hybrid face sheets made from Dyneema fabrics and aluminum plates has the highest buckling load as well as the highest specific buckling load. Also, a specific fixture was designed to laterally clamp the sandwich column which causes a reduction in the probability of specimen end-crushing and significantly increases the buckling load

Experimental investigation of the thin-walled energy absorbers with different sections including surface imperfections under low-speed impact test

Today, investigating the impact phenomenon is of particular importance in different fields. The axial crashing test is considered as one of the most common test with the application in a variety of industries such as the aerospace, shipbuilding, automotive, rail and elevator industries. In this study, the behavior of thin-walled energy absorbers with different circular and square cross-sections has been examined under low-speed impact test. Then, by creating surface defects to reduce the overall weight of the structure as well as reducing the initial peak load, the tests have been continued. It is worth noting that all specimens are made of 1100 series aluminum. The results showed that the highest absorbed energy and highest crashing force efficiency was attributed to the circular beam and simple square beam, respectively

Experimental and numerical study of lattice-core sandwich panels under low-speed impact

In this study, the effect of lattice-core geometry in sandwich panels is studied. The relationship between force and displacement in crushing of the panels has been obtained using the experimental results. Three types of steel lattice cores with different dimensions have been analyzed under axial impact loading. Then, by numerical analysis, the impact parameters such as specific energy absorption are investigated. This type of energy-absorbing system can be used in the aerospace, shipbuilding, automotive, rail and elevator industries to absorb impact energy. According to the obtained results, a good agreement is observed between the experimental results and numerical simulations results. Regarding the axial impact experiments, the specific energy absorption capacity of the sandwich panel can be increased up to 246% by the selection of an appropriate core. In addition, choosing the right core increases the crashing force efficiency up to 214%. Finally, the appropriate geometrical parameters, and the best specimens are presented in terms of the considered criteria with respect to the design objectives