scholarly journals Material Deformation Behavior in T-Shape Hydroforming of Metal Microtubes

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 199 ◽  
Author(s):  
Hajime Yasui ◽  
Shoichiro Yoshihara ◽  
Shigeki Mori ◽  
Kazuo Tada ◽  
Ken-ichi Manabe
Keyword(s):  
Pure Copper ◽  
Material Behavior ◽  
Tube Length ◽  
Process Window ◽  
Forming Limit ◽  
Outer Diameter ◽  
Friction Resistance ◽  
Buckling Resistance ◽  
The Many ◽  
Forming Defects

In this study, the material behavior in the T-shape microtube hydroforming (MTHF) of pure copper and stainless-steel SUS304 microtubes with an outer diameter of 500 µm and wall thickness of 100 µm was examined experimentally and numerically. This paper elucidates the basic deformation characteristics, the forming defects, and the forming limit as well as the effects of lubrication/friction and tube length. The hydroformability (bulge height) of the SUS304 microtube was shown to be higher than that of the copper microtube because of the high buckling resistance of SUS304. Good lubrication experimentally led to the high hydroformability of T-shape forming. The length of the microtube significantly affects its hydroformability. Friction resistance increases with increasing tube length and restricts the flow of the microtube material into the die cavity. By comparing the T-shape and cross-shape MHTF characteristics, we verified the hydroformability of the T-shape microtube to be superior to that of the cross-shape microtube theoretically and experimentally. In addition, the process window for T-shape MTHF had a narrower “success” area and wider buckling and folding regions than that for cross-shape MTHF. Furthermore, conventional finite element (FE) modeling without consideration of the grains was valid for MTHF processes owing to the many grains in the thickness direction.

Study on Forming Feasibility of AISI-5140 Triple Valve by Multi-Way Loading: From Aspect of Geometric Parameters

2011 ◽  
Vol 299-300 ◽  
pp. 982-987 ◽  
Author(s):  
Zhi Chao Sun ◽  
Jiang Hui Wang ◽  
He Yang
Keyword(s):  
Geometric Dimension ◽  
Forming Limit ◽  
Stress And Strain ◽  
Outer Diameter ◽  
Forming Load ◽  
Inner Diameter ◽  
Forming Condition ◽  
Triple Valve ◽  
Forming Defects

Multi-way loading technology provides an efficient method to form integral triple valve parts. However, some forming defects such as cracking and folding are prone to occur, which will weaken the forming limit and quality of formed triple valves. Based on numerical simulation, taking forming load, damage, stress, strain and folding as objectives the forming limit and feasibility were studied by changing geometric dimension of billet and triple valve to be formed. The results showed that (1) for a given billet, as the inner diameter of triple valve increasing, the forming load, maximum damage value, stress and strain increased, i.e. the larger the inner diameter of triple valve the more difficult to form; (2) For triple valves with a given inner-outer diameter ration the maximum damage, maximum stress and strain values increased as triple valve outer diameter decreasing while forming load changed a little. The possibility of folding would augment with the increase of inner-outer diameter ratio d/D, when d/D≥0.8, folding occurred under the forming condition in this paper.

scholarly journals Influence of Internal Pressure and Axial Compressive Displacement on the Formability of Small-Diameter ZM21 Magnesium Alloy Tubes in Warm Tube Hydroforming

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 674 ◽  
Author(s):  
Hajime Yasui ◽  
Taisuke Miyagawa ◽  
Shoichiro Yoshihara ◽  
Tsuyoshi Furushima ◽  
Ryuichi Yamada ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Internal Pressure ◽  
Deformation Behavior ◽  
Tube Hydroforming ◽  
Small Diameter ◽  
Forming Limit ◽  
Outer Diameter ◽  
Fe Method ◽  
Zm21 Magnesium Alloy ◽  
Forming Defects

In this study, the influence of internal pressure and axial compressive displacement on the formability of small-diameter ZM21 magnesium alloy tubes in warm tube hydroforming (THF) was examined experimentally and numerically. The deformation behavior of ZM21 tubes, with a 2.0 mm outer diameter and 0.2 mm wall thickness, was evaluated in taper-cavity and cylinder-cavity dies. The simulation code used was the dynamic explicit finite element (FE) method (FEM) code, LS-DYNA 3D. The experiments were conducted at 250 °C. This paper elucidated the deformation characteristics, forming defects and forming limit of ZM21 tubes. Their deformation behavior in the taper-cavity die was affected by the axial compressive direction. Additionally, the occurrence of tube buckling could be inferred by changes of the axial compression force, which were measured by the load cell during the processing. In addition, grain with twin boundaries and refined grain were observed at the bended areas of tapered tubes. The hydroformed samples could have a high strength. Moreover, wrinkles, which are caused under a lower internal pressure condition, were employed to avoid tube fractures during the axial feeding. The tube with wrinkles was expanded by a straightening process after the axial feed. It was found that the process of warm THF of the tubes in the cylinder-cavity die was successful.

Mechanisms overview of Thermocompression Process for Copper Metal Bonding

2013 ◽  
Vol 1559 ◽  
Author(s):  
Paul Gondcharton ◽  
Floriane Baudin ◽  
Lamine Benaissa ◽  
Bruno Imbert
Keyword(s):  
Functional Integration ◽  
Pure Copper ◽  
Surface Preparation ◽  
Native Oxide ◽  
Process Window ◽  
Wafer Level ◽  
Metallic Oxide ◽  
Copper Diffusion ◽  
Thermomechanical Stress ◽  
Metal Bonding

ABSTRACTWafer level metal bonding involving copper material is widely used to achieve 3D functional integration of ICs and ensure effective packaging sealing for various applications. In this paper we focus on thermocompression bonding technology where temperature and pressure are used in parallel to assist the bonding process. More specifically a broad range of conditions was explored and interesting results were observed and are reported. Indeed, despite a relatively high roughness, the presence of a native oxide and the lack of surface preparation, there still exists a process window where wafer level bonding is allowed. In these conditions, limiting the bonding mechanisms to basic copper diffusion is no longer satisfactory. In this study, a specific scenario inspired by both wafer bonding and metal welding state of the art is put forward. Accordingly, pure copper diffusion through the bonding interface is lined with plastic deformation and metallic oxide fracture. In addition, polycrystalline film deformation due to thermomechanical stress is highlighted and grain growth and voiding formation are observed and confirmed.

Experimental Evaluation of Material Behavior in a Wire Under Transverse Impact

1967 ◽  
Vol 34 (2) ◽  
pp. 392-396 ◽  
Author(s):  
A. B. Schultz ◽  
P. A. Tuschak ◽  
A. A. Vicario
Keyword(s):  
Aluminum Alloy ◽  
Pure Copper ◽  
Closed Form Solution ◽  
Strain Curve ◽  
Simple Wave ◽  
Form Solution ◽  
Material Behavior ◽  
Governing Equations ◽  
Transverse Impact ◽  
Behavior Consistency

Results are reported from an experiment involving photographic observation of constant-velocity transverse impact on long wires of annealed pure copper, two pure aluminums, and an aluminum alloy. Predictions of deformation are made assuming the quasi-static stress-strain curve governs behavior. Consistency with experimental observations is examined. Predictions are based on a closed-form solution to the problem, which is shown to be a compounding of two simple wave solutions of the governing equations. Predictions are consistent with observations for the aluminum alloy even under conditions of moderate or high static prestrain. The two pure aluminums and the copper show consistency at low but not at high strain levels. Highest strain levels reached were in the range 0.06–0.14.

Deformation Behavior and Formability of Sheet Metal Laminate Consisting of Perforated Core Sheet and Thin Skin Sheets

2013 ◽  
Vol 535-536 ◽  
pp. 254-257 ◽  
Author(s):  
Ryutaro Hino ◽  
Masato Nakamura ◽  
Yo Ishida ◽  
Fusahito Yoshida
Keyword(s):  
Sheet Metal ◽  
Biaxial Tension ◽  
Pure Copper ◽  
Uniaxial Stress ◽  
Forming Limit ◽  
Hole Array ◽  
Plastic Behavior ◽  
Thin Skin ◽  
New Type ◽  
Strain Responses

This study presents a new type of sheet metal laminate for lightweight products, and investigates its plastic behavior and formability. The sheet metal laminate consists of three layers, i.e. two thin skin sheets and a perforated core sheet with round holes, which are bonded together by diffusion bonding. Pure copper sheets are used for both of the core and the skins. Plastic deformations of the laminate and its component layers under uniaxial and biaxial tension are examined experimentally and analytically. Results of uniaxial stress-strain responses and yield loci (contours of plastic work) show that the perforated core sheet exhibits anisotropic behavior induced by the hole array but the laminated sheet becomes rather isotropic. Forming limit diagrams of the laminate and its component layers are also obtained by performing stretch forming test. Forming limit of the perforated core sheet is markedly lower than that of the monolithic sheet, and that of the thin skin is in between. It is found that forming limit of the laminate is comparable to that of the thin skin.

scholarly journals Effect of Anisotropic Yield Functions on Prediction of Critical Process Window and Deformation Behavior for Hydrodynamic Deep Drawing of Aluminum Alloys

2020 ◽  
Author(s):  
Chu Wang ◽  
Delun Li ◽  
Bao Meng ◽  
Min Wan
Keyword(s):  
Aluminum Alloys ◽  
Deep Drawing ◽  
Deformation Behavior ◽  
Material Behavior ◽  
Process Window ◽  
Yield Criteria ◽  
Hydrodynamic Deep Drawing ◽  
Plastic Deformation Behavior ◽  
Yield Functions ◽  
Critical Process

Owing to the reduction of rupture instability and the avoidance of wrinkle defect, hydrodynamic deep drawing (HDD) process is gradually becoming attractive for fabricating lightweight and complicated products. Meanwhile, since metallic material presents anisotropic deformation behavior, it is necessary to select an appropriate constitutive model for the prediction of plastic deformation behavior of applied material with high precision. In the present research, several anisotropic yield criteria namely, Hill’48, Yld2000-2d and BBC2005 are implemented to investigate the effect of yield functions on the prediction accuracy of the critical process window and deformation behavior for HDD process of 2024 and 5754 aluminum alloys. Material constants in the yield criteria are determined by applying uniaxial and equi-biaxial tension tests and optimizing an error-function by using the Levenberg-Marquardt algorithm. Furthermore, the process window diagram is computed utilizing the stress analytical model combined material properties with workpiece geometrical features. Numerical simulation results of predicted material anisotropic parameters, process window and HDD deformation for aluminum alloys are compared with the experimental data. Through the comparison of diverse yield criteria based on materials anisotropic coefficients, critical process window prediction, earing profile, and thickness distribution, it is revealed that the Yld2000-2d and the BBC2005 yield criteria can offer more precise models of material behavior in planar anisotropy properties for HDD process of 2024 and 5754 aluminum alloys.

Experimental and Numerical Study on the Evolution of Mechanical Properties During Spiral Pipe Forming

2016 ◽  
Author(s):  
Steven Cooreman ◽  
Dennis Van Hoecke ◽  
Martin Liebeherr ◽  
Philippe Thibaux ◽  
Mary Yamaguti Enderlin
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Numerical Study ◽  
Large Diameter ◽  
Cold Deformation ◽  
Material Behavior ◽  
Strain History ◽  
Outer Diameter ◽  
Complex Deformation ◽  
Detailed Understanding

Large diameter spiral welded pipes are produced from hot rolled coil. The forming of a spiral pipe out of a coil is a sequence of cold deformation steps which are: decoiling, levelling and 3-roll forming (followed by seam welding). Obviously the material experiences a quite complex deformation history since several strain reversals occur during the different steps. A further complexity is that the strain history will even vary along the thickness as it mainly concerns bending deformation. It is therefore not at all surprising that the mechanical properties on pipe and coil are different. The steel manufacturer is able to control the production of the steel within well-defined process limits. Consequently he can guarantee the properties of his product, i.e. the coil. However, the spiral pipe manufacturer only has limited possibilities to control the steel properties but eventually he is responsible for the properties of his product, i.e. the pipe. A detailed understanding of how spiral pipe forming affects the mechanical properties would definitely help steel mills to specify and target coil strength to ensure the final pipe strength. Therefore an experimental study was launched in which a 4-point bending setup was used to reproduce the different forming steps on lab scale. The mechanical properties were measured at intermediate process steps, i.e. on coil, after levelling, after pipe forming and after subsequent flattening. The last step was included because, in practice, the mechanical properties along the pipe transverse direction are typically measured using flattened tensile samples, i.e. after introduction of an additional cold deformation step with strain reversal. The advantages of this experimental approach are twofold: first, one has full control and knowledge on the deformations introduced during the different steps. Second, the typical statistical variation of mechanical properties from coil to coil or even within one coil is far less pronounced as all samples are taken within a relatively short distance from each other. For a more detailed understanding of the experimental study, an efficient Finite Element model to simulate spiral pipe forming was developed in Abaqus. A nonlinear kinematic-isotropic hardening law was applied to describe the material behavior. In this way it was possible to capture both yield point elongation and the well-known Bauschinger phenomenon. This paper summarizes numerical and experimental results for a 16mm thick X70 grade, where different production parameters (leveller settings, ratio of wall thickness to outer diameter) were considered.

scholarly journals Heat Transfer Investigation of Air Flow in Microtubes—Part II: Scale and Axial Conduction Effects

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Ting-Yu Lin ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Scale Effects ◽  
Air Flow ◽  
Tube Length ◽  
Viscous Heating ◽  
Outer Diameter ◽  
Axial Conduction ◽  
Heating Effects ◽  
Nickel Tube ◽  
Inner Diameter

In this paper, the scale effects are specifically addressed by conducting experiments with air flow in different microtubes. Three stainless steel tubes of 962, 308, and 83 μm inner diameter (ID) are investigated for friction factor, and the first two are investigated for heat transfer. Viscous heating effects are studied in the laminar as well as turbulent flow regimes by varying the air flow rate. The axial conduction effects in microtubes are experimentally explored for the first time by comparing the heat transfer in SS304 tube with a 910 μm ID/2005 μm outer diameter nickel tube specifically fabricated using an electrodeposition technique. After carefully accounting for the variable heat losses along the tube length, it is seen that the viscous heating and the axial conduction effects become more important at microscale and the present models are able to predict these effects accurately. It is concluded that neglecting these effects is the main source of discrepancies in the data reported in the earlier literature.

Forming Defects Analysis of Auto-Panel Stamped Part with Experimental Strain Approach

2004 ◽  
Vol 471-472 ◽  
pp. 503-507
Author(s):  
H.Y. Xiang ◽  
Yue Xian Zhong
Keyword(s):  
Experimental Method ◽  
Strain Distribution ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Practical Case ◽  
Stamping Process ◽  
Automobile Panel ◽  
Defects Analysis ◽  
Forming Defects ◽  
Stamped Part

This document explains and demonstrates an experimental method to determine principal plastic strains in industrially stamped sheet panels. The principal strains distribution after a given stamping process can be obtained using computer aided grid experimental method. In contrast with FLD (Forming Limit Diagram) obtained by the material testing, the measured results of strain distribution can be used to determine the sheet metal’s formability allowing to determine at which point the sheet metal cracks or uneven stretch occurs and other forming defects. The main principle and related theory of this approach are discussed. One automobile panel stamped part as a practical case was studied, the strain distribution of the part after a given stamping process was measured and calculated, a demonstration of how to deal with the results in comparison with FLD to determine and solve forming problems is analyzed.

Experimental and Numerical Study on the Effect of Strain Hardening Characteristics on Curved Flaring Process of Pure Copper and Brass

2020 ◽  
Vol 27 (4) ◽  
pp. 39-47
Author(s):  
Tahseen Al-Qahwaji ◽  
Yasir Jobory
Keyword(s):  
Strain Hardening ◽  
Numerical Study ◽  
Pure Copper ◽  
Radius Of Curvature ◽  
Strain Hardening Exponent ◽  
Outer Diameter ◽  
Expansion Process ◽  
Significant Difference ◽  
Base Radius ◽  
Good Agreement

An experimental and numerical study of tube curved flaring process was conducted to investigate the effect of strain hardening characteristic of material on the process using two metals that differ in strain hardening characteristic which are pure copper and brass (70-30) by using curved dies which have curvature ratio ( ρ rd ) of (ρ rd =6) and (ρ rd =12) and base radius of die (rd=24mm) and (ρ) is the radius of curvature. The experimental part was included experiments on specimens with an outer diameter of (39 mm) and a wall thickness of (2 mm). The expansion process was carried out for different expansion ratios that it was reached to about (32%). The results were showed that the strain hardening exponent of pure Copper more than Brass (70-30) and its value reached (0.54) for pure Copper and (0.49) for Brass (70-30). However, this paper concluded a study of the effect of strain hardening characteristics on the curved flaring process. It was found that the increasing of flaring ratio and relative axial displacement of the die through the specimen are caused increase in the relative forming stress, and its value is significant in expanded tubes with high strain hardening characteristic and it is about (0.77) in Brass and (1.42) in Copper. It also found that a little difference in the deformation of specimens' geometry which means that the deformation is not affected by the strain hardening characteristic and there is no significant difference in strain distribution. The study also included a numerical simulation using the finite element ANSYS program. The results obtained are compared with experimental data and showed good agreement.

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