Annisa Jusuf

Numerical and Experimental Impact Analysis of Square Crash Box Structure with Holes

Numerical and experimental study of the effects of center holes located at opposite sides on dynamic axial crushing of thin-walled square aluminum extrusions column are presented in this paper. The results showed that, by inserting the holes, the impact energy absorption characteristic in a progressive buckling can be improved as the starting location of the plastic deformation is always from holes and peak crush force can be decrease, so that the deceleration does not exceed the limit that can injure the passenger when frontal impact occurs. Here, the results of numerical simulations, conducted using an explicit finite element code, are compared with experimental results for various hole diameter. The results shows that the peak crushing force is decrease, while the mean crushing force is relatively constant.

Low Velocity Impact Analyses of Prismatic Columns Using Finite Element Method

This paper presents the study of prismatic columns of different cross sections subjected to low velocity impact, which are commonly used as energy absorber components in vehicles. The impacts of the columns were numerically analyzed using FEM. Four cross sections were considered, i.e. square, hexagonal, octagonal and circular. For each cross section, columns with several combinations of perimeters and thicknesses were analyzed. The results showed that, for columns with equal perimeter and thickness, those with circular cross sections have the highest mean crushing force and those with square cross sections have the lowest crushing forces. Furthermore, keeping all other parameters constant, columns with thicker wall have significantly higher crushing force while columns with longer perimeter have only slightly higher crushing force. This parametric information will be very useful for modern automotive industry in designing front longitudinal members within an acceptable safety level.

Numerical simulation of SHPB to measure the mechanical properties of aluminium foam material at high strain rate by using MAT 163 modified crushable foam

Aluminium foam is a kind of metal foam material which has large energy absorption capability. The mechanical properties of aluminium foam material in high strain rates could be measured by using SHPB. Numerical simulation is used as the initial step to measure mechanical properties of this material. MAT 163 modified crushable foam used as material model in the SHPB numerical simulation of aluminium foam. Numerical simulation showed a quite close results to experimental data.

The Influence of Sheet Metal Forming on The Axial Crushing Analysis of Top–Hat Columns

Reducing the rate of casualty in the crash events is always on the top priority of car manufacturers and customers. It is therefore necessary to make accurate predictions of car structural behavior during the crash events. To achieve this goal, the axial crushing behavior of the thin-walled top hat column needs to be understood thoroughly so that the crashworthiness performance of the column can be predicted accurately. The effect of sheet metal forming should be considered since many car crashworthiness components are fabricated by sheet metal forming. This paper presents a numerical study to investigate sheet metal forming effects such as: thickness distribution, residual stress and plastic strain change to the crushing force characteristics of the top-hat columns. First, the design of the top-hat column was generated by using deep drawing forming process simulation. Then, the forming parameters (geometry, residual stress, plastic strain, thickness distribution) were transferred to the non-linear finite element dynamic analysis model. The axial crushing simulations for the top-hat column with forming parameters were then performed and analyzed. The results showed that the sheet metal forming has a considerable effect on the crush behavior and performance of the thin-walled top-hat columns.

Stress Analysis of the Impactor Assembly of the Dropped Weight Impact Testing Machine

This paper presents the stress analysis of an impactor assembly of a dropped weight impact testing machine. A finite element analysis was performed to calculate the stress occurred on the impactor during the impact which should be less than its yield strength. By varying the level of the reaction load from the specimen to the impactor, the maximum load that can be withstand by the impactor assembly without plastic deformation was predicted. Then, several simulations were carried out to find the best way to increase the load limit of the impactor. It was found out that increasing the thickness of box to 7 mm and both the diameter of arm and frame-column to 40 mm will increase the load limit by 236%.

The Effects of Spot Weld Pitch to the Axial Crushing Characteristics of Top-Hat Crash Box

Numerical study of the effect of spot weld pitch with respect to top-hat crash box crushing characteristics are presented in this paper. Belytschko-Lin-Tsay shell element was used for modeled columns wall with Piecewise Linear Plasticity material model. The impactor was modeled using hexahedral solid elements and assumed as a rigid body. Spot weld joints used to connect mild steel St37 plates of the columns were modeled using beam element and solid element. Impact characteristics related to the spot weld pitch and models were evaluated from simulation results in the form of crushing force vs axial deformation of the column. The results show that spot weld pitch does not significantly affect the crushing characteristics for top-hat crash box with beam element spot weld model, while solid element spot weld model show otherwise. The difference between beam element spot weld model and solid element spot weld model is larger at spot weld pitch 0.50H – H, and tend to close at higher spot weld pitch. Top-hat crash box model becomes stiffer with solid element applied as spot weld model.

Impact Behavior of Square Crash Box Structures Having Holes at Corners

In this paper, an analytical prediction and numerical simulation of the behavior of square crash box structures having hole at corners on dynamic axial crushing are studied. The focus of the present theoretical prediction is to calculate the mean crushing force and maximum crushing force during the folding process subjected to axial impact loading. Then, the effect of hole size to the crushing response of square crash box structures was also evaluated. For validation, an explicit non-linear commercial finite element code LS-DYNA was used to predict the response of the structures subjected to axial crushing. It was found that results of numerical method and theoretical prediction were in good agreement. The results showed that, by inserting holes at corners, the folding can be controlled to be always started from the hole, and peak crush load on the first fold can be reduced significantly. Meanwhile, the decreasing of mean crushing force is insignificant compared to the one without holes. Hence, the characteristic of impact energy absorption in a progressive buckling can be improved, the damage in passenger compartment can be minimized, and the deceleration level can be kept in safe level to prevent injury of the passenger.

Buckling Analysis of Cylindrical Shells Having a Longitudinal Crack

The presence of cracks or similar imperfections can considerably reduce the buckling load of a shell structure. In this paper, buckling analysis of cylindrical shells with a longitudinal crack is presented. Numerical buckling analyses of cylindrical shells were performed using FEM, and verified by experiment. The numerical analyses and experiments were conducted for several crack lengths and radius of curvature, and two different boundary conditions were applied, i.e. simply support and clamp in all sides. The results show the effect of the presence of crack to the critical buckling load of the shells. There are good agreements between experimental and numerical results.