On the strength enhancement under impact loading of square tubes made from rate insensitive metals

Zhao, Han; Abdennadher, Salim

doi:10.1016/j.ijsolstr.2004.05.039

Cited by 71 publications

(39 citation statements)

References 41 publications

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“…Recently, some results were reported in the literature for materials without strain-rate sensitivity, like those shown in Fig. 22 [36].…”

Section: Thermo-visco-plastic Behavior With Johnson-cook Model and LImentioning

confidence: 91%

“…22(a), or showing negative strain-rate sensitivity like some kinds of aluminum alloys [35,36], the collapse will appear on the opposite side of impact and may induce bending of the structure especially for long structure [15,33,37]. In this case the desired high capacity of energy absorption of a structure to protect the passengers will be lost.…”

Section: Thermo-visco-plastic Behavior With Johnson-cook Model and LImentioning

confidence: 99%

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Effect of plastic deformation and boundary conditions combined with elastic wave propagation on the collapse site of a crash box

Rusinek

Zaera

Forquin

et al. 2008

Thin-Walled Structures

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Several papers have been published recently on the crashworthiness studies. The main task was to predict the energy absorption W p and average collapse forceF in time of sheet steel structures. The main objective of this contribution is to design a component that allows absorbing and dissipating a high energy W p allowing improvements of the survivability of passengers in vehicles. However, the range of applications is larger since it includes all civil and military applications related to safety of components, or more generally of construction elements being loaded by impacts or explosions. In the present 3D case, the aim of this numerical study on dynamic loading in adiabatic conditions of deformation is to analyze the effect of elastic wave propagation combined with plastic behavior on the collapse site of a rectangular tubular structure made of steel sheet. To demonstrate the strong coupling between the effects of strain rate sensitivity, accounted for in the constitutive relation that is used in numerical simulations, with the process of elastic wave reflection on the boundary conditions, a series of numerical simulation was performed. It is shown in this numerical study that the strain rate sensitivity influences the position of the first collapse site. Moreover, the first collapse initiation of a structure defines the level of power absorption. Since the process of folding may be combined with bending of the structure (in particular when a local buckling appears close to the opposite side of impact), in this non axial case the energy absorption W p decreases and the effectiveness of the structure to the energy absorption is insufficient.

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“…Recently, some results were reported in the literature for materials without strain-rate sensitivity, like those shown in Fig. 22 [36].…”

Section: Thermo-visco-plastic Behavior With Johnson-cook Model and LImentioning

confidence: 91%

Section: Thermo-visco-plastic Behavior With Johnson-cook Model and LImentioning

confidence: 99%

Effect of plastic deformation and boundary conditions combined with elastic wave propagation on the collapse site of a crash box

Rusinek

Zaera

Forquin

et al. 2008

Thin-Walled Structures

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“…The spheres are quite brittle and the failure mode of the agglomerate is a successive breaking of sphere layers. There is then no supplementary rate sensitivity due to the structural effect such as the inertia effect because spheres are typically considered as Type I structure [21][22]. D2431 exhibits a gradient profile of an unbalanced inverse V-shape with less dense ends whereas E4123 has an unbalanced V-shape density profile with more dense ends.…”

Section: Epoxy Hollow Spheresmentioning

confidence: 99%

Impact behaviour of hollow sphere agglomerates with density gradient

Zeng¹,

Pattofatto²,

Zhao³

et al. 2010

International Journal of Mechanical Sciences

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Abstract. This paper presents a study on the influence of the density gradient profile on the mechanical response of graded polymeric hollow sphere agglomerates under impact loading.Quasi-static, standard split Hopkinson pressure bar (SHPB) tests as well as higher speed direct impact Hopkinson bar tests and Taylor tests are performed on such hollow sphere agglomerates with various density gradient profiles. It is found that the density gradient profile has a rather limited effect on the energy absorption capacity from those tests. It is because the testing velocity performed (<50 m/s) is rather small with respect to its average sound wave speed (around 500 m/s) and the equilibrium stress state can be reached rather quickly. The high impact tests allow to generate a non-equilibrium state condition and the influence of density profiles is clearly observed. Besides, in order to extend this study to the situation beyond our testing limitations, a numerical model is built on the basis of the experimental behaviour data. It confirms the important influence of the density gradient profile under a non-equilibrium stress state situation. This study shows that placing the hardest layer as the first impacted layer and the weakest layer as the last layer has some benefits in terms of maximum energy absorption with a minimum force level transmitted to the protected structures.

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“…Elnasri et al [9] reported a limited rate sensitivity for ALPORAS foam at strain rates up to 1300 m/s. Zhao and Abdennadher [10] stated that the rate sensitivity of metallic foam is due to inertia effects in dynamic buckling of cell walls, although the foam is made of strain rate insensitive material. Klintworth [11] and Reid and Peng [12] discussed the possibility for the strength increase in cellular structures that, under dynamic conditions, the collapse mechanism of the foam changes from the quasi-static mode to a dynamic mode involving additional stretching of the cell wall that dissipates more energy.…”

Section: Introductionmentioning

confidence: 99%

Propagation of a stress wave through a virtual functionally graded foam

Kiernan

Cui

Gilchrist

2009

International Journal of Non-Linear Mechanics

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Stress wave propagation through a Functionally Graded Foam Material (FGFM) is analysed in this paper using the Finite Element Method. A Finite Element model of the Split Hopkinson Pressure Bar (SHPB) is developed to apply realistic boundary conditions to a uniform density foam and is validated against laboratory SHPB tests. Wave propagation through virtual FGFMs with various gradient functions are then considered. The amplitude of the stress wave is found to be shaped by the gradient functions, i.e. the stress can be amplified or diminished following propagation through the FGFMs. The plastic dissipation energy in the specimens is also shaped by the gradient functions. This property of FGFMs provides significant potential for such materials to be used for cushioning structures.

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On the strength enhancement under impact loading of square tubes made from rate insensitive metals

Cited by 71 publications

References 41 publications

Effect of plastic deformation and boundary conditions combined with elastic wave propagation on the collapse site of a crash box

Effect of plastic deformation and boundary conditions combined with elastic wave propagation on the collapse site of a crash box

Impact behaviour of hollow sphere agglomerates with density gradient

Propagation of a stress wave through a virtual functionally graded foam

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