Foam-filled Thin-walled Tubes Research Articles

Experimental study on the impact resistance of hollow thin-walled aluminum alloy tubes and foam-filled aluminum tubes (6063-T5)

This paper presents a study on the axial impact resistance of hollow thin-walled aluminum alloy tubes and aluminum foam-filled thin-walled tubes. 15 hollow thin-walled aluminum alloy tubes and 15 thin-walled aluminum alloy tubes filled with aluminum foam were tested under drop hammer impacts. The process of the impact, the failure modes of the specimens, the time history curves of impact forces, and the vertical deflections were recorded in the test. The effects of impact velocity, aluminum alloy wall thickness, cross-sectional width, and aluminum foam on the performance of the hollow and aluminum foam-filled thin-walled aluminum alloy tubes were discussed. In addition, a finite element model was established to simulate the test considering the strain rate effect of aluminum alloy and aluminum foam. The results showed that both hollow and foam-filled thin-walled aluminum alloy tubes were damaged to different degrees. Under the same impact energy, the damage of the foam-filled thin-walled aluminum alloy tube was less severe than that of the hollow thin-walled aluminum alloy tube; under the axial impact load of the drop hammer, the most effective way to improve the impact resistance of the hollow and foam-filled thin-walled aluminum alloy tubes was to increase the wall thickness of the outer thin-walled aluminum alloy tube, while the effect of increasing the cross-sectional size of the outer thin-walled aluminum alloy tube on the impact resistance of the specimen is less significant. The peak impact force, vertical deflection and the duration of impact forces are most sensitive to the impact velocity.

Development of tubes filled with aluminium foams for lightweight vehicle manufacturing

This paper aims to investigate different filling methods of ex situ aluminium foam-filled thin-walled Al alloy tubes to determine the best option for possible applications in automotive industry. The main applied filling methods were joining with heat dilatation, mechanical compression and adhesive bonding. Foam specimens were prepared by shaping and machining operations from an original foam block. The density of the filler foams was 250 kg/m3, 500 kg/m3 and 750 kg/m3 respectively. The foam rods were inserted into empty thin-walled tubes and subjected to quasi-static bending and compression loading conditions. The connection methods between the aluminium foam and the thin-walled tube were examined by microscopy technique. The quality of the assemble was highly influenced by the filling method itself and the surface defects caused by machining operations. The foam-filled tubes, empty tubes and foams were compared in terms of the maximum load carry capacity, specific load capacity, crash energy absorption and specific energy absorption. The obtained results showed that adhesive bonding has the best specific load carrying ability under quasi-static bending loading. Also, it had the lowest average total weight of the specimens. The maximum flexure displacement achieved by the heat dilatation filling method and the minimum was reached by mechanical compression method. Adhesive bonding and mechanical compression showed good energy absorption capabilities against bending loading. The maximum specific energy absorption was produced by density of 750 kg/m3 but the failure of the specimens came earlier than in case of fillers with lower densities. The foams with density of 250 kg/m3 had the lowest specific values but they had the highest displacement values. The machinability is directly proportional with the growing of density. Foams with a density of 500 kg/m3 are very good fillers because they can be machined well, have the best specific load-bearing capacity and less cell displacement under load. The 500 kg/m3 was the best density for ex situ filling with all this in mind. In the case of compression tests, the stress-strain curve of the adhesive bonding filling method exceeded the sum of the stress-strain curve of individual components. The specific energy absorption curve of the adhesive bonding method overtakes the curve of the empty tube at a certain strain.The novelty of this article is the application, investigation and comparison of different filling methods for the production of ex situ foam-filled thin-walled tubes. The experiments were made with very small wall thickness which is even harder to fill with metal foams. The machinability of aluminium foams was also tested in this article. Overall, the goal was to produce foam-filled structures with tools that are widely used in the automotive industry.

Numerical crashworthiness analysis of a novel functionally graded foam-filled tube

The thin-walled tubes used in the front rails of the vehicle’s body in white play a major role in absorbing the energy of the collision. In this work, the energy absorption characteristics of the functionally graded foam-filled thin-walled tubes are studied by using quasi-static finite element analysis. The simulation of all specimens has been conducted by utilizing finite element software ABAQUS/Explicit™. A high-precision constitutive equation is used to obtain mechanical properties of foam in different densities. Uniform density foam-filled and functionally graded foam-filled tubes with various gradient functions and configurations are simulated, and force–displacement and energy–displacement diagrams are extracted and compared to each other. The simulation carried out on the layered samples showed that the 13-layered sample is an appropriate approximation for the continuous variations of density along the axial direction. According to the results, linear variations have had better energy absorption characteristics compared to the samples with gradient exponent of [Formula: see text] = 2 and [Formula: see text] = 5 for an ascending density variation. In this study, the innovative density variation patterns as high-low-high and low-high-low are also simulated in which the high-low-high sample has better energy absorption than other specimens. It is shown for 13-layered samples, the specific energy absorption in the high-low-high design is 3 and 6.6% higher than the ascending pattern ( m = 1) and the low-high-low samples, respectively.

Axial and radial compressive properties of alumina-aluminum matrix syntactic foam filled thin-walled tubes

The alumina-aluminum matrix syntactic foam filled thin-walled tubes (FFTs) were prepared by inserting aluminum matrix syntactic foams reinforced with alumina hollow spheres with three size ranges (1.0–1.5 mm, 1.5–2.0 mm and 2.5–3.0 mm) into empty aluminum alloy tubes. For comparison with as cast samples, each type of syntactic foam underwent a T6 heat treatment. The FFTs and individual components were compressed in axial and radial directions. During axial compression, FFTs deformed by concertina mode, which was different from the diamond mode of tubes and the deformation characteristics of syntactic foams dominated by brittle fracture. The deformation mode of FFTs under radial compression was consistent with syntactic foams. The axial energy absorption was always greater than the radial energy absorption for FFTs and individual components under the same conditions. Regardless of the compression direction, the energy absorption of FFTs was higher than the sum of individual components. The energy absorption varied with hollow sphere size and heat treatment. The axial interaction effect between syntactic foam and tube in FFTs increased with deformation. The FFTs exhibited excellent specific energy absorption under axial and radial compression.

Crashworthiness performance and microstructural characteristics of foam-filled thin-walled tubes under diverse strain rate

The implementation of Aluminum Alloy Foam (AAF) has made an impact in automobile and aerospace applications where crash energy absorption, vibration and sound damping and weight reduction is obligatory. The AAF is an emerging lightweight material providing high strength and stiffness at relatively low density. This research is carried out to quantify the energy absorption of mild steel reinforced AAF having empty mild steel and foam-filled tubes for different strain rates and geometry parameters. The AAF used in the current study is AlSi10Mg foam of densities 0.45, 0.65, 0.85 g/cm3, which is produced using melt route process. The circular, square and rectangular geometries were tested at strain rates of 0.1, 1, 10 mm/s. From the obtained compressive stress-strain curves Specific Energy Absorption (SEA), Total Energy Absorption (TEA), plateau stress of the empty and filled sections were determined, which were then evaluated. AAF was assessed by both light and electron microscopy. Field Emission Scanning Electron Microscope (FESEM) and Analysis of Variance (ANOVA) technique was employed to investigate the highest contributing factor in energy absorption. It was observed that foam filled tube can absorb more energy than empty tubes before reaching densification point.

Comparative analysis of crashworthiness of empty and foam-filled thin-walled tubes

Quasi-static axial compression tests were conducted on two types of empty aluminum alloy tubes (circular and square) and five types of aluminum ex-situ foam filled tube structures (foam-filled single circular and square tubes, foam-filled double circular and square tubes, and corner-foam-filled square tube). The load-deformation characteristics, deformation mode and energy absorption ability of these structures were investigated. Several parameters related to their crashworthiness were compared, including the specific energy absorption, the energy-absorbing effectiveness factor, etc. The influence of physical dimension on the crashworthiness of these structures was explored. Dimensions of the inner tube were found to have significant influence on the structural crashworthiness of foam-filled double tubes. The averaged crush force, specific energy absorption, energy absorption per stroke and energy-absorbing effectiveness factor of thin-walled circular structures are higher than those of thin-walled square structures, respectively. Foam-filled single and double circular tube structures are recommended as crashworthy structures due to their high crush force efficiency and energy-absorbing efficiency.

Bending resistance and energy-absorbing effectiveness of empty and foam-filled thin-walled tubes

A comparative study on the crashworthiness characteristics of different cylindrical tubular structures under quasi-static three-point bending, such as thin-walled empty tube, foam-filled single tube structure and foam-filled double tube structure was carried out. The load–deformation characteristics, failure modes and energy absorption capacity of different structures were investigated. Typical characteristic parameters to measure crashworthiness of a structure, namely energy absorption, specific energy absorption (SEA) and energy-absorbing effectiveness factor were systematically studied and compared to identify a potential structural component for vehicle engineering applications. The experimental results confirmed that when subjected to bending, the total energy absorption, SEA and energy-absorbing effectiveness of foam-filled double structures were relatively higher than those of the empty and foam-filled single structures. Foam-filled double square and circular tube structures are recommended as crashworthy structures due to their high bending resistance and energy-absorbing effectiveness.

Parametric analysis and multiobjective optimization for functionally graded foam-filled thin-wall tube under lateral impact

Foam-filled thin-walled tubes have proven an ideal energy absorber in automotive industry for its extraordinary energy-absorbing ability and lightweight potential. Unlike existing uniform foam (UF), this paper introduces functionally graded foam (FGF) to fill into the thin-walled structure subjected to lateral impact loading, where different configurations of foam grading (axial FGF and two transverse FGFs) are considered. To systematically investigate the bending behavior of this novel structure, numerical model is established using nonlinear finite element analysis code LS-DYNA and then is validated against the experiment. Through parametric study, it is found that the FGF tube absorbs more energy but may produce larger force than the UF counterpart. In addition, various parameters have a considerable effect on the crashworthiness performance of the FGF filled tube. Finally, multiobjective optimizations of UF and FGF filled columns are conducted, aiming to improve the specific energy absorption (SEA) and reduce the maximum impact force simultaneously, based upon the multiobjective particle optimization (MOPSO) algorithm and Kriging modeling technique. The optimization results show that all the FGF filled tubes can produce better Pareto solutions than the ordinary UF counterpart. Furthermore, the axial FGF tube provides better energy absorption characteristics than the two types of transverse FGF tubes.

Off-Axis Crushes Simulation of Thin-walled Tapered Tubes Inserted with Foam-filled Structures

In this study deal with numerical analysis of the impact dynamic effects of crush performance of the tapered cross-section tubes, containing straight, single taper, double taper, taper triple and fourth tapered lightweight polyurethane foam filled alloy steel thin-walled tube. Foam-filled thin-walled tubes have been examined numerically. Off-axis angle load dynamic effects in front of crash were examined at an angle of 0, 5, 10, 15 and 20 degrees. Numerical analysis has been verified by experimental studies in place to validate the data. The results show that the energy absorption capacity has been significantly affected tube with various oblique angle, impact velocity and wall thickness. It was found that the foam filling in a thin-walled tubes increase the amount of energy absorbed compared with empty tubes.

Experimental and Numerical Crashworthiness Investigation of Empty and Foam-Filled Thin-Walled Tubes with Shallow Spherical Caps

Thin-walled structures have been extensively used as energy absorbers in crashworthiness applications such as automobile and aeronautical industries to protect passengers from severe injury. This paper investigates the energy absorption responses of empty and foam-filled cylindrical and conical tubes with shallow spherical caps under quasi-static axial loading. Nonlinear dynamic finite element analyses are carried out to investigate the details concerning crushing process. Satisfactory agreements are achieved between the finite element and the experimental results. The numerical and experimental results highlight several effects of foam filling on the crushing behavior of the thin-walled tubes. Finally, the effect of semi-apical angle on the crushing behavior of the empty and foam-filled tubes with shallow spherical caps is investigated. This study provides practical information about using thin-walled tubes with shallow spherical caps as energy absorbers in aerospace applications in order to design reentry sounding rocket based on foam-filled tube with shallow spherical caps.

Crushing response of foam-filled conical tubes under quasi-static axial loading

Foam-filled thin-walled tubes are considered to be desirable energy absorbers under axial loading due to their higher energy absorption compared with empty tubes. This paper treats the axial crushing and energy absorption response of foam-filled conical tubes under quasi-static axial loading, using non-linear finite element models. Influence of important parameters such as wall thickness, semi-apical angle and density of foam filler was investigated and the results highlight the advantages of using foam-filled conical tubes as energy absorber. Results also indicate that the crush and energy absorption performances of conical tubes are significantly enhanced by foam filling. The primary outcome of the study is new research information and development of empirical relations which will facilitate the design of foam-filled conical tubes as energy absorbers in impact applications.

Parametric study and numerical analysis of empty and foam-filled thin-walled tubes under static and dynamic loadings

In this paper the crushing behavior of thin-walled tubes under static and dynamic loading is investigated. First, a finite element (FE) model for empty thin-walled tube was constructed and validated by available experimental and numerical data. The comparison between the FE results and the existing numerical solutions as well as the available experimental results showed good agreements. Next, a model for the foam was adopted and implemented in an in-house FE code. The implemented isotropic foam model was then used to simulate the behavior of foam-filled tubes under both static and dynamic loadings. Good agreement was observed between the results from the model with those obtained by analytical relations and experimental test data. The validated FE model was then used to conduct a series of parametric studies on foam-filled tapered tubes under static and dynamic loadings. The parametric studies were carried out to determine the effect of different parameters such as the number of oblique sides, foam density and boundary conditions on crushing behavior of rectangular tubes. The characteristic included deformed shapes, load–displacement, fold length and specific energy absorptions.

Modeling the progressive axial crushing of foam-filled aluminum tubes using smooth particle hydrodynamics and coupled finite element model/smooth particle hydrodynamics

As alternatives to the classical finite element model (FEM), a meshless smooth particle hydrodynamics (SPH) method, in which the discrete particles represent a solid domain, and a coupled FEM/SPH modeling technique were investigated for the numerical simulation of the quasi-static axial crushing of polystyrene foam-filled aluminum thin-walled aluminum tubes. The results of numerical simulations, load-deformation histories, fold lengths and specific absorbed energies, were found to show satisfactory correlations with those of experiments and FEM. The results further proved the capabilities of the SPH Method and coupled FEM/SPH modeling technique in predicting the crushing behavior of foam-filled thin-walled tubes.

Design and finite element simulations of aluminium foam-filled thin-walled tubes

This paper presents experiences gained at SIMLab in modelling and design of aluminium-foam-filled tubes for structural applications. The main challenges for robust finite element simulations using explicit codes are outlined and references to previous studies are used for illustration. Any details whatsoever may be found in the original papers referenced in the text.