Effect of Continuous Direct Current on the Yield Stress of Stainless Steel 304 Micro Tubes During Hydroforming Operations

2012 ◽  
Author(s):  
Scott W. Wagner ◽  
Kenny Ng ◽  
William J. Emblom ◽  
Jaime A. Camelio
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
High Pressures ◽  
Tube Hydroforming ◽  
Process Equipment ◽  
Traditional Methods ◽  
Macro Scale ◽  
Hydroforming Process ◽  
Superior Mechanical Properties ◽  
Electrically Assisted Manufacturing

Hydroforming at the macro scale offers the opportunity to create products that have superior mechanical properties and intricate complex geometries. Micro tube hydroforming is a process that is gaining popularity for similar reasons. At the same time, due to the physical size of the operations, there are many challenges including working with extremely high pressures and available materials that are typically difficult to form. Increasing the formability of micro tubes during the hydroforming process is desired. Being able to increase the formability is essential because as the tube diameters decrease in size, the required forming pressure increases. As a result, it is important to explore methods to decrease the yield stress during forming operations. Traditional methods for decreasing the materials yield stress typically involve heating either the sample or the process equipment. Using traditional methods typically sacrifice dimensional quality of the part, alter the mechanical properties and also raise the costs of the operations. Electrically Assisted Manufacturing (EAM) is a non-traditional method that is gaining popularity by reducing the necessary forces and pressures required in metal forming operations.

Influence of Continuous Direct Current on the Micro Tube Hydroforming Process

2011 ◽  
Author(s):  
Scott W. Wagner ◽  
Kenny Ng ◽  
William J. Emblom ◽  
Jaime A. Camelio
Keyword(s):  
Direct Current ◽  
Metal Forming ◽  
High Pressures ◽  
Tube Hydroforming ◽  
Electrical Current ◽  
Deformation Energy ◽  
Electrically Assisted ◽  
Macro Scale ◽  
Hydroforming Process ◽  
Electrically Assisted Manufacturing

Research of the micro tube hydroforming (MTHF) process is being investigated for potential medical and fuel cell applications. This is largely due to the fact that at the macro scale the tube hydroforming (THF) process, like most metal forming processes has realized many advantages. Unfortunately, large forces and high pressures are required to form the parts so there is a large potential to create failed or defective parts. Electrically Assisted Manufacturing (EAM) and Electrically Assisted Forming (EAF) are processes that apply an electrical current to metal forming operations. The intent of both EAM and EAF is to use this applied electrical current to lower the metals required deformation energy and increase the metal’s formability. These tests have allowed the metals to be formed further than conventional methods without sacrificing strength or ductility. Currently, various metal forming processes have been investigated at the macro scale. These tests also used a variety of materials and have provided encouraging results. However, to date, there has not been any research conducted that documents the effects of applying Electrically Assisted Manufacturing (EAM) techniques to either the tube hydroforming process (THF) or the micro tube hydroforming process (MTHF). This study shows the effects of applying a continuous direct current to the MTHF process.

Influence of Continuous Direct Current on the Microtube Hydroforming Process

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Scott W. Wagner ◽  
Kenny Ng ◽  
William J. Emblom ◽  
Jaime A. Camelio
Keyword(s):  
High Pressures ◽  
Tube Hydroforming ◽  
Electrical Current ◽  
Deformation Energy ◽  
Recrystallization Temperature ◽  
Machining Processes ◽  
Electrically Assisted ◽  
Stainless Steel 304 ◽  
Hydroforming Process ◽  
Electrically Assisted Manufacturing

Research of the microtube hydroforming (MTHF) process is being investigated for potential medical and fuel cell applications. This is largely due to the fact that at the macroscale the tube hydroforming (THF) process, like most metal forming processes, has realized many advantages, especially when comparing products made using traditional machining processes. Unfortunately, relatively large forces compared to part size and high pressures are required to form the parts so the potential exists to create failed or defective parts. One method to reduce the forces and pressures during MTHF is to incorporate electrically assisted manufacturing (EAM) and electrically assisted forming (EAF) into the MTHF. The intent of both EAM and EAF is to use electrical current to lower the required deformation energy and increase the metal's formability. To reduce the required deformation energy, the applied electricity produces localized heating in the material in order to lower the material's yield stress. In many cases, the previous work has shown that EAF and EAM have resulted in metals being formed further than conventional forming methods alone without sacrificing the strength or ductility. Tests were performed using “as received” and annealed stainless steel 304 tubing. Results shown in this paper indicate that the ultimate tensile strength and bust pressures decrease with increased current while using EAM during MTHF. It was also shown that at high currents the microtubes experienced higher temperatures but were still well below the recrystallization temperature.

scholarly journals Non-Auxetic Mechanical Metamaterials

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 635 ◽  
Author(s):  
Christa de Jonge ◽  
Helena Kolken ◽  
Amir Zadpoor
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Fatigue Behavior ◽  
Analytical Data ◽  
Three Dimensional ◽  
Mechanical Metamaterials ◽  
Macro Scale ◽  
Unit Cells ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

The concept of “mechanical metamaterials” has become increasingly popular, since their macro-scale characteristics can be designed to exhibit unusual combinations of mechanical properties on the micro-scale. The advances in additive manufacturing (AM, three-dimensional printing) techniques have boosted the fabrication of these mechanical metamaterials by facilitating a precise control over their micro-architecture. Although mechanical metamaterials with negative Poisson’s ratios (i.e., auxetic metamaterials) have received much attention before and have been reviewed multiple times, no comparable review exists for architected materials with positive Poisson’s ratios. Therefore, this review will focus on the topology-property relationships of non-auxetic mechanical metamaterials in general and five topological designs in particular. These include the designs based on the diamond, cube, truncated cube, rhombic dodecahedron, and the truncated cuboctahedron unit cells. We reviewed the mechanical properties and fatigue behavior of these architected materials, while considering the effects of other factors such as those of the AM process. In addition, we systematically analyzed the experimental, computational, and analytical data and solutions available in the literature for the titanium alloy Ti-6Al-4V. Compression dominated lattices, such as the (truncated) cube, showed the highest mechanical properties. All of the proposed unit cells showed a normalized fatigue strength below that of solid titanium (i.e., 40% of the yield stress), in the range of 12–36% of their yield stress. The unit cells discussed in this review could potentially be applied in bone-mimicking porous structures.

Numerical analysis in a beverage can utilizing tube hydroforming process

2019 ◽  
Vol 28 (6) ◽  
pp. 77-83
Author(s):  
Jorge Carlos León Anaya ◽  
José Antonio Juanico Loran ◽  
Juan Carlos Cisneros Ortega
Keyword(s):  
Mechanical Properties ◽  
Numerical Analysis ◽  
Metal Forming ◽  
Tube Hydroforming ◽  
Forming Process ◽  
Aluminum Tube ◽  
Plastic Deformation Process ◽  
Metal Forming Process ◽  
Hydroforming Process

Numerical analysis for Tube Hydroforming (THF) was developed in this work to predict the behavior of extruded aluminum tube in a forming die for beverage can applications. THF is a metal forming process dependent of three parameters: friction between the tube and the die, internal pressure, and material properties of the tube. Strain hardening is a governing phenomenon that occurs in the plastic deformation process of metals. Hollomon’s equation offers a mathematical description of the metal behavior in the plastic zone. For a proper simulation, experimental determination of the mechanical properties of aluminum 6061-T5 were conducted and test specimens where obtained directly from the aluminum tube. Experimental data were necessary because no sufficient data of the mechanical properties of the tube were available in the literature. Numerical simulations of THF were performed, and the results were compared with analytical results for validation purposes with less than 10% of error.

DMV 25.7 N

Alloy Digest ◽  
2000 ◽  
Vol 49 (5) ◽  
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Pressures ◽  
Heat Treating ◽  
Temperature Performance ◽  
Superior Corrosion Resistance

Abstract DMV 25.7 N is a superferritic-austenitic grade with high mechanical properties and superior corrosion resistance to chlorides, freshwater, and high pressures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-785. Producer or source: DMV Stainless USA Inc.

Metallic Nanoneedles Arrays for TEM Sample Preparation “Lift-Out”

2012 ◽  
Author(s):  
Romaneh Jalilian ◽  
David Mudd ◽  
Neil Torrez ◽  
Jose Rivera ◽  
Mehdi M. Yazdanpanah ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Sample Preparation ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Beam System ◽  
Transmission Electron ◽  
Nanoneedle Array ◽  
Superior Mechanical Properties ◽  
And Performance

Abstract The sample preparation for transmission electron microscope can be done using a method known as "lift-out". This paper demonstrates a method of using a silver-gallium nanoneedle array for a quicker sharpening process of tungsten probes with better sample viewing, covering the fabrication steps and performance of needle-tipped probes for lift-out process. First, an array of high aspect ratio silver-gallium nanoneedles was fabricated and coated to improve their conductivity and strength. Then, the nanoneedles were welded to a regular tungsten probe in the focused ion beam system at the desired angle, and used as a sharp probe for lift-out. The paper demonstrates the superior mechanical properties of crystalline silver-gallium metallic nanoneedles. Finally, a weldless lift-out process is described whereby a nano-fork gripper was fabricated by attaching two nanoneedles to a tungsten probe.

Determination of mechanical properties of two-phase and hybrid nanocomposites: experimental determination and multiscale modeling

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mahmoud Haghighi ◽  
Hossein Golestanian ◽  
Farshid Aghadavoudi
Keyword(s):  
Mechanical Properties ◽  
Ultimate Strength ◽  
Multiscale Modeling ◽  
Filler Content ◽  
Hybrid Nanocomposites ◽  
Dynamics Simulation ◽  
Strength Increase ◽  
Two Phase ◽  
Macro Scale ◽  
Elongation To Failure

Abstract In this paper, the effects of filler content and the use of hybrid nanofillers on agglomeration and nanocomposite mechanical properties such as elastic moduli, ultimate strength and elongation to failure are investigated experimentally. In addition, thermoset epoxy-based two-phase and hybrid nanocomposites are simulated using multiscale modeling techniques. First, molecular dynamics simulation is carried out at nanoscale considering the interphase. Next, finite element method and micromechanical modeling are used for micro and macro scale modeling of nanocomposites. Nanocomposite samples containing carbon nanotubes, graphene nanoplatelets, and hybrid nanofillers with different filler contents are prepared and are tested. Also, field emission scanning electron microscopy is used to take micrographs from samples’ fracture surfaces. The results indicate that in two-phase nanocomposites, elastic modulus and ultimate strength increase while nanocomposite elongation to failure decreases with reinforcement weight fraction. In addition, nanofiller agglomeration occurred at high nanofiller contents especially higher than 0.75 wt% in the two-phase nanocomposites. Nanofiller agglomeration was observed to be much lower in the hybrid nanocomposite samples. Therefore, using hybrid nanofillers delays/prevents agglomeration and improves mechanical properties of nanocomposite at the same total filler content.

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