scholarly journals Thermally Induced Mechanical Response of Metal Foam During Laser Forming

2018 ◽  
Vol 140 (4) ◽  
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.

Bending Mechanism Analysis for Laser Forming of Metal Foam

2017 ◽  
Author(s):  
Tizian Bucher ◽  
Adelaide Young ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Y. Lawrence Yao
Keyword(s):  
Temperature Gradient ◽  
Sheet Metal ◽  
Metal Foam ◽  
Numerical Models ◽  
Image Correlation ◽  
Laser Forming ◽  
Mechanism Analysis ◽  
Forming Process ◽  
Experimental Proof ◽  
Post Process

To date, the industrial production of metal foam components has remained challenging, since 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. What prevents the industrial implementation of the method, however, is that no detailed experimental analysis has been done of the metal foam strain response during laser forming, and hence the existing numerical models have been insufficiently validated. Moreover, current understanding of the laser forming process is poor, and it has been assumed, without experimental proof, that the temperature gradient mechanism (TGM) from sheet metal forming is the governing mechanism for metal foam. In this study, these issues were addressed by using digital image correlation (DIC) to obtain in-process and post-process strain data that was then used to validate a numerical model. Additionally, metal foam laser forming was compared with metal foam 4-point bending and sheet metal laser forming to explain why metal foam can be bent despite its high bending stiffness, and to evaluate whether TGM is valid for metal foam. The strain measurements revealed that tensile stretching is only a small contributor to foam bending, with the major contributor being compression-induced shortening. Unlike in sheet metal laser forming, this shortening is achieved through cell wall bending, as opposed to plastic compressive strains. Based on this important difference with traditional TGM, a modified temperature gradient mechanism (MTGM) was proposed.

scholarly journals Mechanical Performance Under Various Conditions of 3D Printed Polylactide Composites With Natural Fibers

2021 ◽  
Author(s):  
Karolina E. Mazur ◽  
Aleksandra Borucka ◽  
Paulina Kaczor ◽  
Szymon Gądek ◽  
Stanislaw Kuciel
Keyword(s):  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Natural Fibers ◽  
Crystallization Rate ◽  
Mechanical Tests ◽  
Hydrothermal Degradation ◽  
3D Printed ◽  
The Impact ◽  
Different Levels ◽  
Additive Methods

Abstract In the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by additive methods were tested. The effect of type fiber, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different level of infilling result in a similar level of reduction in the properties. Composites made of PLA are more sensitive to high temperature than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Moreover, the impact strength has been improved by 50% for composites with cork particles and for other lignocellulosic composites remained at the same level as for resin.

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

2019 ◽  
Vol 141 (5) ◽  
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 ◽  
The Impact

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.

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

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.

3D Laser Forming of Metal Foam Sandwich Panels

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.

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

2021 ◽  
Author(s):  
Tom Zhang ◽  
Yubin Liu ◽  
Y. Lawrence Yao
Keyword(s):  
Metal Foam ◽  
Metal Foams ◽  
Laser Forming ◽  
Test Scheme ◽  
Compression Tests ◽  
Forming Process ◽  
Band Formation ◽  
Static Compression ◽  
Energy Absorbing ◽  
The Impact

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.

scholarly journals The influence of the inter-ply hybridisation on the mechanical performance of composite laminates: Experimental and numerical analysis

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110232
Author(s):  
Hussein Dalfi ◽  
Anwer J Al-Obaidi ◽  
Hussein Razaq
Keyword(s):  
Elastic Constants ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Failure Modes ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Numerical Study ◽  
Geometric Model ◽  
Woven Fabric ◽  
The Impact

Recently, high tensile fibres composite laminates (i.e. glass composite laminates) have been widely used in the civil and military applications due to their superior properties such as lightweight, fatigue and corrosion resistance compared to metals. Nevertheless, their brittle fracture behaviour is a real downside for many sectors. In the present study, the impact of the hybridisation of Kevlar woven layers with glass woven layers on the reducing the strain failure problem in pure glass woven laminates is investigated. In this work, multi-layers Kevlar-glass with different stacking sequences have been used to prepare the hybrid composite laminates using vacuum–assisted resin moulding method. The influence of the layers hybridisation on the mechanical performance of composites laminates was investigated using tensile strength tests. Furthermore, finite element analysis is performed to analyse the mechanical response of the hybrid composite laminates using Abaqus software. The elastic constants of woven fabric layers in the numerical study were predicted through geometric model based on the textile geometry and analytical method in order to assert accuracy of the predicted elastic constants. The experimental results showed that the hybrid composite laminates tend to fail more slowly than glass woven laminates, which illustrates low strain to failure. In the theoretical part of the study, it was found that the proposal model can be useful to capture the mechanical behaviour and the damage failure modes of hybrid laminates. Thus, the catastrophic failure can be avoided in these laminates.

3D Laser Forming of Metal Foam Sandwich Panels

2020 ◽  
Vol 142 (8) ◽  
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 the 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 also 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 bending mechanisms and process parameters identified for 2D laser forming translate to 3D deformation. Additionally, the impact of the laser scan length was determined by comparing different scan patterns that achieve the same 3D geometries. It was shown that laser forming could induce 3D deformation necessary for both bowl and saddle shapes, the two fundamental non-Euclidean geometries. The amount of laser-induced bending and in-plane strains vary depending on process conditions and the governing 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.

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

2019 ◽  
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 ◽  
The Impact

Abstract 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 towards 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, as well as the adhesion method on the bending efficiency and 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.

scholarly journals Laser Forming of Sandwich Panels With Metal Foam Cores

2018 ◽  
Vol 140 (11) ◽  
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 ◽  
The Impact

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.

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