Crashworthiness Optimization of Thin Walled Cylindrical Tubes with Annular Grooves under Axial Compression

2012 ◽  
Vol 463-464 ◽  
pp. 30-35 ◽  
Author(s):  
Reza Emami ◽  
Elahe Sadat Alavi Moghadam ◽  
Mostafa Sohrabi
Keyword(s):  
Maximum Load ◽  
Absorbed Energy ◽  
Optimal Point ◽  
Composite Function ◽  
Explicit Finite Element ◽  
Cylindrical Tubes ◽  
Allowable Load ◽  
Design Requirements ◽  
Energy Absorbers ◽  
Crushing Behavior

In this paper explicit finite element codes of LS DYNA are applied to simulate the crushing behavior of cylindrical metallic impact energy absorbers with annular machined grooves and the validation of the simulation results are done by comparing with experimental and theoretical findings from the literature. Some efforts are made to find the optimum groove geometry of the tubes by considering two criteria such as the maximum absorbed energy per unit mass (SEA) and maximum ratio of average load to maximum load during crushing (CFE). Maximum allowable load during crushing and the geometrical limits that should not exceed some specified boundaries are considered as design constrains. Based on design of experiment technique (DOE) the conditions that the results should be taken are determined and consequently, response surface (RS) models are created to build a composite objective function that considers both CFE and SEA. Genetic algorithm is applied to find the optimal point for the composite function that meets the design requirements.

Crashworthiness Performance of Mass-Efficient Extruded Structures

2002 ◽  
Author(s):  
Robert R. Mayer ◽  
Weigang Chen ◽  
Anil Sachdev
Keyword(s):  
Numerical Simulations ◽  
Single Cell ◽  
Experimental Testing ◽  
Experimental Studies ◽  
Nonlinear Material ◽  
Dynamic Strain ◽  
Cell Design ◽  
Explicit Finite Element ◽  
The One ◽  
Crushing Behavior

Theoretical, numerical and experimental studies were conducted on the axial crushing behavior of traditional single-cell and innovative four-cell extrusions. Two commercial aluminum alloys, 6061 and 6063, both with two tempers (T4 and T6), were considered in the study. Testing coupons taken from the extrusions assessed the nonlinear material properties. A theoretical solution was available for the one-cell design, and was developed for the mean crushing force of the four-cell section. Numerical simulations were carried out using the explicit finite element code LS-DYNA. The aluminum alloy 6063T4 was found to absorb less energy than 6061T4, for both the one-cell and four-cell configurations. Both 6061 and 6063 in the T6 temper were found to have significant fracture in the experimental testing. Theoretical analysis and numerical simulations predicted a greater number of folds for the four-cell design, as compared to the one-cell design, and this was confirmed in the experiments. The theoretical improvement in energy absorption of 57% for the four-cell in comparison with the one-cell design was confirmed by experiment. The good agreement between the theoretical, numerical and experimental results allows confidence in the application of the theoretical and numerical tools for both single-cell and innovative four-cell extrusions. It was also demonstrated that these materials have very little dynamic strain rate effect.

On the Crushing Behavior of Foam-Filled Composite Tubes under Compressive Loading

2012 ◽  
Vol 626 ◽  
pp. 1038-1041 ◽  
Author(s):  
Akbar Othman ◽  
Shahrum Abdullah ◽  
Ahmad Kamal Ariffin ◽  
Nik Abdullah Nik Mohamed ◽  
Helmi Rashid
Keyword(s):  
Energy Absorption ◽  
Wall Thickness ◽  
Peak Load ◽  
Compressive Loading ◽  
Absorbed Energy ◽  
Polymeric Foam ◽  
Foam Filled ◽  
Marine Applications ◽  
Crushing Behavior ◽  
Initial Peak

The present papers determine the effect of composite pultrusion square tubes E-glass polyester empty and polymeric foam-filled subjected to axial compressive loading. The specimens of square composite pultrusion were compressed experimentally under axial loadings to examine the effect of empty and polymeric foam-filled with different wall-thickness. The wall-thickness was used in this study were 2.1 and 2.4 mm. During the experimental observation, three characteristic crushing stages were identified as initial peak load, progressive crushing and compaction zone stages. The composite pultrusion square tube profile were analyzed and investigated in terms of crashworthiness parameters to meet the improvement of structural material widely used in automobile, aerospace and marine applications. Result obtained from experimental analysis such that initial peak load, mean load, energy absorption and specific energy absorption versus displacement curves were compared for each specimen. Results showed that the tubes energy absorption was affected significantly by different tube profile. It is also found that the polymeric foam-filled exhibit superb crashworthy structure on specific absorbed energy and the amount of initial peak load, mean load and absorbed energy recorded higher than the empty tube profiles.

A Novel Theoretical Approach for Estimation of Axial Crushing Behavior of Polygonal Hollow Sections

2020 ◽  
Vol 12 (01) ◽  
pp. 2050008
Author(s):  
Ahmad Malekshahi ◽  
Kourosh Heidari Shirazi ◽  
Mohammad Shishesaz ◽  
Mohammad Hosseini
Keyword(s):  
Plastic Deformation ◽  
Fe Simulation ◽  
Progressive Collapse ◽  
Plastic Hinge ◽  
Absorbed Energy ◽  
Crushing Force ◽  
Thin Walled ◽  
Hinge Model ◽  
Crushing Behavior ◽  
Novel Model

The aim of the present study was to introduce new crushing mechanisms in terms of crushing modes for estimating the crushing force and absorbed energy of polygonal thin walled metal sections subjected to axial progressive collapse. For this purpose, two models were developed. The first model, which has been extensively used before and named as “plastic hinge model” (PHM), was modified based on new crushing modes; and as the second, a novel model was introduced by the authors named as “induced curvature model” (ICM). The latter model was considered to be more realistic than the former due to consideration of metal sheet curvatures during progressive folding process, as well as including the hardening effect of the material during plastic deformation. All possible crushing modes for a typical polygonal section were considered and discussed by combining different crushing modes of the corner elements. New expressions for the absorbed energies and crushing force were presented based on the resulting crushing modes. To evaluate the validity and efficiency of the proposed models, a detailed FE simulation was conducted using LS-DYNA. Comparison of FEM, PHM and ICM results showed the superiority of the ICM over PHM.

scholarly journals PRELIMINARY MECHANICAL TEST OF PROXIMAL FEMUR REINFORCEMENT WITH CEMENTED X-SHAPED PMMA

2018 ◽  
Vol 26 (4) ◽  
pp. 231-235
Author(s):  
Anderson Freitas ◽  
Welvis Soares Camargo ◽  
Ruben Jeri Aquino ◽  
Vincenzo Giordano Neto ◽  
Aluízio Fernandes Bonavides Junior ◽  
...  
Keyword(s):  
Mechanical Test ◽  
Maximum Load ◽  
Bending Test ◽  
Control Group ◽  
Group Level ◽  
Absorbed Energy ◽  
Greater Trochanter ◽  
Level Of Evidence ◽  
Static Mechanical ◽  
Mechanical Bending

ABSTRACT Objective: To evaluate the mechanical behavior of the proximal end of the femur submitted to the X-shaped polymethylmethacrylate (PMMA) reinforcement technique. Methods: Fifteen synthetic femurs, with a Nacional® density of 10 PCF, were divided into two groups: the DX group, with 5 units that were submitted to PMMA reinforcement, and the DP group, with 10 units, which were evaluated intact. The volume of PMMA required, the maximum load, and the absorbed energy to fracture were analyzed by means of a static mechanical bending test simulating a fall on the greater trochanter. Results: A mean of 6 ml of PMMA was used to model the X-reinforcement; it was observed that the DX group presented significantly higher maximum load (median = 1553 N, p = 0.005) and absorbed energy to fracture (median = 9.7 J; p = 0.050) than the DP group (median = 905 N and 6.6 J). Conclusion: X-reinforcement of the proximal end of synthetic femurs showed a statistically significant increase in the maximum load and absorbed energy to fracture in the mechanical assay when compared to the control group. Level of Evidence III, Experimental study.

scholarly journals Design of Structure of Tension Leg Platform for 6 MW Offshore Wind Turbine Based On Fem Analysis

2017 ◽  
Vol 24 (s1) ◽  
pp. 230-241 ◽  
Author(s):  
Jędrzej Żywicki ◽  
Paweł Dymarski ◽  
Ewelina Ciba ◽  
Czesław Dymarski
Keyword(s):  
Wind Turbine ◽  
Structural Changes ◽  
Ad Hoc ◽  
Wind Wave ◽  
Fem Analysis ◽  
Maximum Load ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Design Requirements ◽  
Made In

Abstract The article presents the calculation and design stages of the TLP platform serving as a supporting construction of a 6 MW offshore wind turbine. This platform is designed to anchor at sea at a depth of 60 m. The authors presented the method of parameterization and optimization of the hull geometry. For the two selected geometry variants, the load and motion calculations of the platform subjected to wind, wave and current under 50-year storm conditions were performed. The maximum load on the structure was determined in these extreme storm conditions. For these loads, the MES calculation of the designed platform was performed for the selected variant. Authors have presented a method for calculating maximum wind, wave and current stresses on the structure during the worst storm in the past 50 years. For these loads the MES endurance calculations of the designed platform were made. Based on the results of these calculations, the required structural changes and recalculations have been made in succession to the structural design of the platform, which meets the design requirements and has the required ad hoc strength. The article contains stress analysis in „difficult“ nodes of constructions and discusses ways of solving their problems. The work is part of the WIND-TU-PLA project from the NCBR Research Agreement (Agreement No. MARTECII / 1/2014).

scholarly journals Energy Absorption Due to Oblique Impact Crushing of Thin-Walled Tubes

2018 ◽  
Vol 183 ◽  
pp. 04001
Author(s):  
Tsutomu Umeda ◽  
Koji Mimura
Keyword(s):  
Strain Rate ◽  
Fuel Efficiency ◽  
Cylindrical Tube ◽  
Initial Imperfection ◽  
Oblique Impact ◽  
Buckling Load ◽  
The Mean ◽  
Thin Walled ◽  
Energy Absorbers ◽  
Crushing Behavior

From the viewpoint of improving both the crash safety and the fuel efficiency, various shaped thin-walled tubes have been utilized as energy absorbers of automobiles such as front side members, crash boxes and so forth. In the axial crushing test of the regular polygonal tube, if the number of angles was small enough, it showed a certain inherent wrinkle mode, and the mean buckling load increased with that number, while it showed the mode of cylindrical tube if that number became larger. In the oblique crushing test, the same tendency was also shown within the range that the transition from axial collapse to bending collapse did not occur. This transition considerably decreases the mean buckling load so that it is important to know the threshold crush angle for the transition. Then, the crushing behavior of regular 4-12 angled tubes were investigated with changing the crush angle mainly by the experiment. The threshold angle is sensitively influenced by the initial imperfection and the boundary condition so that both the threshold angles obtained by the experiment and by the calculation for the square tube are 8-13° smaller than that predicted by the equation proposed by Han and Park. For the carbon steel S25C, the increase of the strain rate in the axial collapse mode raises the mean buckling load, while it shows little strain rate dependence once the transition occurs.

Optimization Design of Towbarless Aircraft Tractor Frame Based on ANSYS Workbench

2012 ◽  
Vol 268-270 ◽  
pp. 921-925
Author(s):  
Li Wen Wang ◽  
Qiang Wang ◽  
Wei Zhang
Keyword(s):  
Finite Element ◽  
Topology Optimization ◽  
Static Analysis ◽  
Working Conditions ◽  
Optimization Design ◽  
Bending Strength ◽  
Maximum Load ◽  
Original Design ◽  
Design Requirements ◽  
Ansys Workbench

The 3-D frame model of towbarless aircraft tractor was established with the UG software, and then transferred into ANSYS Workbench to conduct the finite element static analysis to check the bending strength of the frame on maximum load working conditions. Using topology optimization module, original design of frame was optimized in accordance with the calculation result. It shows that the strength of optimized frame meet the design requirements, while the weight of optimized frame is reduced by 8%.

An Inductive Design Exploration Method for the Integrated Design of Multi-Scale Materials and Products

2005 ◽  
Author(s):  
Hae-Jin Choi ◽  
Janet K. Allen ◽  
David Rosen ◽  
David L. McDowell ◽  
Farrokh Mistree
Keyword(s):  
Integrated Design ◽  
Material Structure ◽  
Product Analysis ◽  
Optimal Point ◽  
Design Exploration ◽  
Design Synthesis ◽  
Robust Solution ◽  
Multi Scale ◽  
Point Solution ◽  
Design Requirements

In this paper, we propose an Inductive Design Exploration Method (IDEM) which can be used to design materials and products concurrently and systematically. IDEM facilitates hierarchical materials and product design synthesis, which includes multi-scale material structure and product analysis chains, and uncertainty in models and its propagation through the chains. In this method, we sequentially identify a ranged set of feasible specifications, instead of an optimal point solution in each segment of a hierarchical design process. The feasible spaces are searched from top-level design requirements to product and materials specifications taking into account propagated uncertainty. Strategies for parallelizing computations and achieving a robust solution for uncertainty in models are also addressed. The method is demonstrated with a simple example of designing a clay-filled polyethylene cantilever beam.

scholarly journals Coupled Effect of Thickness Optimization and Plastic Forming History on Crashworthiness Performance of Thin-Walled Square Tube

2021 ◽  
Author(s):  
Hasan Sofuoglu ◽  
Salim Çam
Keyword(s):  
Rolling Process ◽  
Drawing Process ◽  
High Velocity Impact ◽  
Thickness Optimization ◽  
Absorbed Energy ◽  
Deep Drawing Process ◽  
Coupled Effect ◽  
Plastic Forming ◽  
Thin Walled ◽  
Energy Absorbers

Abstract Thin-walled tubes are widely used as energy absorbers due to their high crashworthiness performance. This study aims to evaluate the effect of plastic forming history carried out for thickness optimization on crashworthiness performance of thin-walled square tube (TWST). Within the scope of the study, a series of numerical analyses were conducted for the TWST using a commercial finite element (FE) software. In order to determine individual effect of optimization, FG thickness of TWST was first obtained using LS-OPT software. Later, thickness gradient was achieved by performing rolling process to consider individual plastic forming effect Afterwards, deep drawing process was carried out to shape TWST by considering springback and trimming effects. Finally, crash responses were obtained under axial high velocity impact loading to determine the coupled effect of optimization and plastic forming on the crashworthiness performance of the TWST. It was determined that the coupled effect, which takes plastic forming and optimization effects into account, reduced the peak crush force of the TWST by 24% and increased the absorbed energy value by 39%. The results obtained from this study showed that coupled effect of optimization and plastic forming processes has significant effect on the crashworthiness performance of the TWST and otherwise either overestimated or underestimated results are obtained.

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