Effect of Laser Forming on the Energy Absorbing Behavior of Metal Foams

Abstract Metal foam is light in weight and exhibits an excellent impact absorbing capability. Laser forming has emerged as a promising process in shaping metal foam plates into desired geometry. While the feasibility and shaping mechanism has been studied, the effect of the laser forming process on the mechanical properties and the energy absorbing behavior in particular of the formed foam parts has not been well understood. This study comparatively investigated such effect on as-received and laser formed closed-cell aluminum alloy foam. In quasi-static compression tests, attention was paid to the changes in the elastic region. Imperfections near the laser irradiated surface were closely examined and used to help elucidate the similarities and differences in as-received and laser formed specimens. Similarly, from the impact tests, the dynamically induced deformation and crush band formation were investigated with a modified Charpy impact test scheme. Differences in specific energy absorption were studied and were related to the defects formed during laser forming process. The relative density distribution and evolution of foam specimens were numerically investigated. Laser induced imperfections lead to very minor decrease in the energy absorbing ability of the metal foam, and laser forming still remain as a viable shaping process for metal foams.

Effect of Laser Forming on the Energy Absorbing Behavior of Metal Foams

10.1115/1.4051285 ◽

2021 ◽

pp. 1-29

Author(s):

Tom Zhang ◽

Yubin Liu ◽

Nathan Ashmore ◽

Wayne Li ◽

Y. Lawrence Yao

Keyword(s):

Metal Foam ◽

Laser Forming ◽

Compression Tests ◽

Forming Process ◽

Static Compression ◽

Closed Cell ◽

Similarities And Differences ◽

Energy Absorbing ◽

The Impact ◽

Quasi Static Compression

Abstract Metal foam is light in weight and exhibits an excellent impact absorbing capability. Laser forming has emerged as a promising process in shaping metal foam plates into desired geometry. While the feasibility and shaping mechanism has been studied, the effect of the laser forming process on the mechanical properties and the energy absorbing behavior in particular of the formed foam parts has not been well understood. This study comparatively investigated such effect on as-received and laser formed closed-cell aluminum alloy foam. In quasi-static compression tests, attention paid to the changes in the elastic region. Imperfections near the laser irradiated surface were closely examined and used to help elucidate the similarities and differences in as-received and laser formed specimens. Similarly, from the impact tests, differences in deformation and specific energy absorption were focused on, while relative density distribution and evolution of foam specimens were numerically investigated.

Laser Forming of Sandwich Panels With Metal Foam Cores

10.1115/1.4040959 ◽

2018 ◽

Vol 140 (11) ◽

Cited By ~ 8

Author(s):

Tizian Bucher ◽

Steven Cardenas ◽

Ravi Verma ◽

Wayne Li ◽

Y. Lawrence Yao

Keyword(s):

Power Plants ◽

Metal Foam ◽

Sandwich Panels ◽

Laser Forming ◽

Process Conditions ◽

Foam Core ◽

Mechanism Analysis ◽

Forming Process ◽

Solar Power Plants ◽

Over the past decade, laser forming has been effectively used to bend various metal foams, opening the possibility of applying these unique materials in new engineering applications. The purpose of the study was to extend laser forming to bend sandwich panels consisting of metallic facesheets joined to a metal foam core. Metal foam sandwich panels combine the excellent shock-absorption properties and low weight of metal foam with the wear resistance and strength of metallic facesheets, making them desirable for many applications in fields such as aerospace, the automotive industry, and solar power plants. To better understand the bending behavior of metal foam sandwich panels, as well as the impact of laser forming on the material properties, the fundamental mechanisms that govern bending deformation during laser forming were analyzed. It was found that the well-established bending mechanisms that separately govern solid metal and metal foam laser forming still apply to sandwich panel laser forming. However, two mechanisms operate in tandem, and a separate mechanism is responsible for the deformation of the solid facesheet and the foam core. From the bending mechanism analysis, it was concluded on the maximum achievable bending angle and the overall efficiency of the laser forming process at different process conditions. Throughout the analysis, experimental results were complemented by numerical simulations that were obtained using two finite element models that followed different geometrical approaches.

The Fracture Properties of Sandwich Structures Based on a Metal Foam Core

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.936.2054 ◽

2014 ◽

Vol 936 ◽

pp. 2054-2062

Author(s):

Yiou Shen ◽

Yan Li ◽

Wesley Cantwell ◽

Yu Yuan Zhao

Keyword(s):

Metal Foam ◽

Sandwich Structures ◽

Compaction Pressure ◽

Metal Foams ◽

Compression Tests ◽

Fracture Properties ◽

Indentation Tests ◽

Point Bend ◽

Average Size ◽

Two Parameters

The fracture properties of a series of metal foam sandwich structures based on glass fiber-reinforced polyamide 6,6 composite (GF/PA6,6) skins have been investigated. The open cell core materials were manufactured using the Lost Carbonate Sintering (LCS) process, a recently-developed technique for manufacturing metal foams. Initially, the effect of varying the compaction pressure used in producing the metal foams as well as the density of the samples were investigated through a series of compression tests. Here, it was shown that the compressive strength and the elastic modulus of the foams varied with density and compaction pressure, in spite of the fact that the average size of the cells in these foams were insensitive to either of these two parameters. The resistance of sandwich structures to localized loading was investigated through a series of indentation tests. Here, it was shown that the indentation response of sandwich structures could be characterized using a simple indentation law, the parameters of which did not exhibit any clear dependency on the density of the foam. Finally, three point bend tests on the sandwich structures have shown that their loading-bearing properties were sensitive to foam density.

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

Experimental investigation of the quasi-static and impact tests on the energy absorption characteristics of coupler rubber buffers used in railway vehicles

10.1177/0954409718819570 ◽

2018 ◽

Vol 233 (9) ◽

pp. 937-950 ◽

Cited By ~ 1

Author(s):

Shuguang Yao ◽

Zhixiang Li ◽

Wen Ma ◽

Ping Xu ◽

Quanwei Che

Keyword(s):

Energy Absorption ◽

Impact Velocity ◽

High Speed ◽

Compression Tests ◽

Static Compression ◽

Static Tests ◽

Impact Tests ◽

High Speed Trains ◽

The Impact ◽

Absorption Characteristics

Coupler rubber buffers are widely used in high-speed trains, to dissipate the impact energy between vehicles. The rubber buffer consists of two groups of rubbers, which are pre-compressed and then installed into the frame body. This paper specifically focuses on the energy absorption characteristics of the rubber buffers. Firstly, quasi-static compression tests were carried out for one and three pairs of rubber sheets, and the relationship between the energy absorption responses, i.e. Eabn = n × Eab1, Edissn = n × Ediss1, and Ean = Ea1, was obtained. Next, a series of quasi-static tests were performed for one pair of rubber sheet to investigate the energy absorption performance with different compression ratios of the rubber buffers. Then, impact tests with five impact velocities were conducted, and the coupler knuckle was destroyed when the impact velocity was 10.807 km/h. The results of the impact tests showed that with the increase of the impact velocity, the Eab, Ediss, and Ea of the rear buffer increased significantly, but the three responses of the front buffer did not increase much. Finally, the results of the impact tests and quasi-static tests were contrastively analyzed, which showed that with the increase of the stroke, the values of Eab, Ediss, and Ea increased. However, the increasing rates of the impact tests were higher than that of the quasi-static tests. The maximum value of Ea was 68.76% in the impact tests, which was relatively a high value for the vehicle coupler buffer. The energy capacity of the rear buffer for dynamic loading was determined as 22.98 kJ.

Thermally Induced Mechanical Response of Metal Foam During Laser Forming

10.1115/1.4038995 ◽

2018 ◽

Vol 140 (4) ◽

Cited By ~ 7

Author(s):

Tizian Bucher ◽

Adelaide Young ◽

Min Zhang ◽

Chang Jun Chen ◽

Y. Lawrence Yao

Keyword(s):

Temperature Gradient ◽

Mechanical Response ◽

Metal Foam ◽

Mechanical Performance ◽

Image Correlation ◽

Laser Forming ◽

Experimental Proof ◽

Thermally Induced ◽

The Impact ◽

Different Levels

To date, metal foam products have rarely made it past the prototype stage. The reason is that few methods exist to manufacture metal foam into the shapes required in engineering applications. Laser forming is currently the only method with a high geometrical flexibility that is able to shape arbitrarily sized parts. However, the process is still poorly understood when used on metal foam, and many issues regarding the foam's mechanical response have not yet been addressed. In this study, the mechanical behavior of metal foam during laser forming was characterized by measuring its strain response via digital image correlation (DIC). The resulting data were used to verify whether the temperature gradient mechanism (TGM), well established in solid sheet metal forming, is valid for metal foam, as has always been assumed without experimental proof. Additionally, the behavior of metal foam at large bending angles was studied, and the impact of laser-induced imperfections on its mechanical performance was investigated. The mechanical response was numerically simulated using models with different levels of geometrical approximation. It was shown that bending is primarily caused by compression-induced shortening, achieved via cell crushing near the laser irradiated surface. Since this mechanism differs from the traditional TGM, where bending is caused by plastic compressive strains near the laser irradiated surface, a modified temperature gradient mechanism (MTGM) was proposed. The densification occurring in MTGM locally alters the material properties of the metal foam, limiting the maximum achievable bending angle, without significantly impacting its mechanical performance.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

10.1115/1.4043194 ◽

2019 ◽

Vol 141 (5) ◽

Cited By ~ 4

Author(s):

Tizian Bucher ◽

Min Zhang ◽

Chang Jun Chen ◽

Ravi Verma ◽

Wayne Li ◽

...

Keyword(s):

Metal Foam ◽

Numerical Models ◽

Sandwich Panels ◽

Weight Ratio ◽

Industrial Applications ◽

Laser Forming ◽

Process Conditions ◽

Foam Core ◽

Wide Range ◽

Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road toward a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, and the adhesion method on the bending efficiency and the bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

Volume 2: Manufacturing Processes; Manufacturing Systems; Nano/Micro/Meso Manufacturing; Quality and Reliability ◽

3D Laser Forming of Metal Foam Sandwich Panels

10.1115/msec2020-8210 ◽

2020 ◽

Author(s):

Tizian Bucher ◽

Connor Finn ◽

Ravi Verma ◽

Wayne Li ◽

Y. Lawrence Yao

Keyword(s):

Metal Foam ◽

Sandwich Panels ◽

Absorption Capacity ◽

Laser Forming ◽

Process Conditions ◽

Practical Engineering ◽

3D Deformation ◽

Panel Thickness ◽

The Impact ◽

Scan Length

Abstract Metal foam sandwich panels have been subject of many concept studies, due to their exceptional stiffness, light weight, and crash absorption capacity. Yet, the industrial production of the material has been hampered by the fact that it is challenging to bend the material into practical engineering shapes. Only recently it has been shown that bending of metal foam sandwich panels is possible using lasers. It was shown that the material can be bent into Euclidean (2D) geometries, and the governing laser-induced bending mechanisms were analyzed. This study was focused on laser forming of metal foam sandwich panels into non-Euclidean (3D) geometries. It was investigated whether the knowledge about the bending mechanisms translates to 3D deformation, and whether the combination of process parameters that were identified for 2D laser forming are still appropriate. Moreover, the impact of the laser scan length was determined by comparing different scan patterns that achieve the same 3D geometries. It was shown that 3D deformation could be induced for both the bowl and saddle shapes, the two most fundamental non-Euclidean geometries. The amount of laser-induced bending and in-plane strains vary depending on process conditions and thus bending mechanisms. Lastly, the laser scan length was shown to become more important for metal foam sandwich panels, where the panel thickness tends to be large.

Study on Preparation Method and Energy-Absorbing Characteristics of Carbon Fiber Composite Energy Absorber

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.442.98 ◽

2013 ◽

Vol 442 ◽

pp. 98-103

Author(s):

Chang Jie Luo ◽

Hai Liang Zhang ◽

Wen Ze Yu ◽

Kai He ◽

Ru Xu Du

Keyword(s):

Carbon Fiber ◽

Preparation Method ◽

Fiber Composite ◽

Compression Tests ◽

Carbon Fiber Composite ◽

Energy Absorber ◽

Static Compression ◽

Advantages And Disadvantages ◽

Energy Absorbing ◽

Composite Energy

By analyzing advantages and disadvantages of the existing energy absorbers, carbon fiber composite and regular hexagon honeycomb structure were chosen as material and topological structure respectively to make a big-bearing, lightweight energy absorber. Preparation method of carbon fiber composite honeycomb energy absorber was studied, which was applied to manufacture some specimens,and it is feasible because of the specimens good consistency and regularity. Quasi-static compression tests of the specimens were carried out, and then the related parameters of energy-absorbing characteristics were calculated. The results show that the carbon fiber composite honeycomb energy absorber has excellent energy-absorbing characteristics.

Dynamic and Quasi-Static Compression Tests for Polylactic Acid Resin Foam

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.745 ◽

2012 ◽

Vol 706-709 ◽

pp. 745-750 ◽

Cited By ~ 2

Author(s):

Hidetoshi Kobayashi ◽

Keitaro Horikawa ◽

Keiko Watanabe ◽

Kinya Ogawa ◽

Kensuke Nozaki

Keyword(s):

Strain Rate ◽

Polylactic Acid ◽

High Speed ◽

Impact Load ◽

Video Camera ◽

Compression Tests ◽

Rate Dependency ◽

Static Compression ◽

Acid Resin ◽

In this study, the effect of strain rate on the strength and the absorbed energy of polylactic acid resin foam (PLA-foam), which is generally known as one of carbon-neutral and environmentally-friendly polymers, were examined by a series of compression tests at various strain rates from 0.001 to 750 s-1. For the measurements of the impact load and the displacement of specimen, a special load cell and a high-speed video camera were used, respectively. The flow stress of the PLA-foam strongly depends upon not only strain rate but also density of specimens. Thus, a new technique to eliminate the effect of the difference in the specimen density was proposed and successfully applied. It was also found that the strain-rate dependency of PLA-foam can be expressed by a simple power law.

Investigation and Statistical Modeling of the Mechanical Properties of Additively Manufactured Lattices

Materials ◽

10.3390/ma14143962 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3962

Author(s):

Derek G. Spear ◽

Anthony N. Palazotto

Keyword(s):

Mechanical Properties ◽

Mechanical Performance ◽

Design Parameters ◽

Statistical Experimental Design ◽

Lattice Structures ◽

Compression Tests ◽

Static Compression ◽

Interaction Terms ◽

Cell Densities ◽

This paper describes the background, test methodology, and experimental results associated with the testing and analysis of quasi-static compression testing of additively manufactured open-cell lattice structures. The study aims to examine the effect of lattice topology, cell size, cell density, and surface thickness on the mechanical properties of lattice structures. Three lattice designs were chosen, the Diamond, I-WP, and Primitive Triply Periodic Minimal Surfaces (TPMSs). Uniaxial compression tests were conducted for every combination of the three lattice designs, three cell sizes, three cell densities, and three surface thicknesses. In order to perform an efficient experiment and gain the most information possible, a four-factor statistical experimental design was planned and followed throughout testing. A full four-factor statistical model was produced, along with a reduced interactions model, separating the model by the significance of each factor and interaction terms. The impact of each factor was analyzed and interpreted from the resulting data, and then conclusions were made about the effects of the design parameters on the resultant mechanical performance.