Showing papers on "Hydroforming published in 2008"
TL;DR: In this paper, the performance of different anisotropic yield functions in predicting the response and burst of tubes loaded under combined internal pressure and axial load was evaluated, and the results were used to calibrate the non-quadratic yield functions of Hosford and Karafillis-Boyce.
112 citations
14 May 2008
TL;DR: The state-of-the-art of tube hydroforming can be found in this paper, where the authors present the principles of hydroforming, equipment, controls and tooling for tubular hydroforming.
Abstract: Introduction and state-of-the-art of hydroforming. Part 1 Principles of hydroforming: Hydroforming systems, equipment, controls and tooling Deformation mechanism and fundamentals of hydroforming Materials and their characterization for hydroforming Formability analysis for tubular hydroformed parts Design and modeling of parts, process and tooling in tube hydroforming Tribological aspects in hydroforming. Part 2 Hydroforming techniques and their applications: Pre-forming: Tube rotary draw bending and pre-flattening/crushing in hydroforming Hydroforming: hydropiercing, end-cutting, and welding Hydroforming sheet metal forming components Bending and hydroforming of aluminum and magnesium alloy tubes Low pressure tube hydroforming Comparative analysis of hydroforming techniques Fluid cell pressing in the aerospace industry Hydroforming and its role in lightweighting automobiles Warm hydroforming.
76 citations
TL;DR: In this article, the effect of channel size and shape on the manufacturability of micro-feature arrays was investigated from a manufacturing perspective, and the results from the parametric study suggested that in order to obtain the maximum aspect ratio (height-to-width ratio) a small channel width should be used.
70 citations
TL;DR: In this article, the formability of aluminum tubes was investigated using a combination of experimental and numerical approaches, where the tubes were loaded to failure under combined internal pressure and axial load along radial paths in the engineering stress space.
70 citations
TL;DR: Based on the plastic membrane theory and force equilibrium equations, a unique approach is proposed with the curve fitting of experimental data to determine the stress-strain relationship of a thin-walled tube in hydroforming process (THF) as mentioned in this paper.
Abstract: Based on the plastic membrane theory and force equilibrium equations, etc., a unique approach is proposed with the curve fitting of experimental data to determine the stress–strain relationship of a thin-walled tube in hydroforming process (THF). A simple and practical hydraulic bulge test tooling was developed and free-bulged tests were performed on stainless steel and low carbon steel tubes to obtain required experimental deformation data. Finite element (FE) simulations of the free bulges were carried out to verify the approach indirectly. The results indicate that the present approach is accurate and acceptable to define the stress–strain behavior of tubular material, and furthermore, an extended flow stress curve with large strain can be obtained by the approach.
54 citations
TL;DR: In this article, a new approach to tube bulge test is described, which is related to the fact that the tube ends are blocked and so the equilibrium expression in axial direction normally used to calculate stresses is no more valid.
50 citations
TL;DR: In this article, the authors present extensive possibilities of component development in automotive industry by means of hydroforming processes and also presented some examples on computer modelling of these processes and limiting phenomena.
45 citations
TL;DR: In this paper, an adaptive simulation approach integrated with a fuzzy logic control algorithm is used to obtain a part with the required shape and minimize the tube wall thickness variation during Tee extrusion tube hydroforming process.
44 citations
TL;DR: In this article, the effect of the pre-bulging pressure and the cutoff pressure on thickness distribution and surface finish in hydro-mechanical deep drawing were studied. And it was found out that thickness distribution along cup wall is more uniform for intermediate prebulging pressures.
43 citations
TL;DR: In this article, a combined heating system consisting of an induction coil plus a heating element was applied to the warm hydroforming of aluminum alloy tubes for rapid heating of tubes, a specially designed induction heating system has been developed as the main heating source.
42 citations
TL;DR: In this paper, the authors focused on the determination of optimum sheet metal forming process and process parameters for various cross sectional workpieces by comparing the numerical results of high-pressure sheet metal formation, hydro-mechanical deep drawing (DD) and conventional DD simulations.
Abstract: This study focuses on the determination of optimum sheet metal forming process and process parameters for various cross sectional workpieces by comparing the numerical results of high-pressure sheet metal forming, hydro-mechanical deep drawing (DD) and conventional DD simulations. Within the range of each cross section, depth, characteristic dimensions ratio and fillet radius have been altered systematically. Steel of types St14 and DC04 have been used as the specimen material in the numerical analyses and the experimental verification throughout the study. All numerical simulations have been carried out by using a dynamic–explicit commercial finite element code and an elasto-plastic material model. During the analyses each workpiece was simulated by the three competing processes. The results of analyses, such as sheet thickness distribution, necking, forming of radii etc., are used for assessing the success of each forming process alternative. The analyses revealed that depending on the workpiece geometry and dimensional properties certain processes are preferable for obtaining more satisfactory products. Working windows for each process have been established based on the analyzed parameters of the circular, elliptic, rectangular and square cross sectional product geometries. This data is expected to be useful for selecting the appropriate production process for a given workpiece geometry and understand the limits of each sheet metal forming processes.
TL;DR: In this paper, an analytical model for planar tube hydroforming based on deformation theory has been developed, which can be used to predict hydroformed shape, corner fill, wall thinning, and forming pressure.
TL;DR: An approach for substituting conventional manufacturing method of a three pieces shell fender by one piece has been proposed in this article, which is based on sheet hydroforming process, which has many advantages over conventional stamping processes.
TL;DR: In this article, the authors have demonstrated that material data obtained from tube bulging test were more suitable than the classical tensile test for performing pertinent numerical simulations of tube hydroforming process, and they have shown that hardening curves can be obtained through the measurement of internal pressure and bulge height; thickness variation along the bulged part of the tube can be calculated; scattering on the hardening curve can be evaluated by using inaccuracy of measurement point location during experiments and manufacturing tolerances on tube thickness.
TL;DR: In this article, the superplastic forming of Aluminium alloy 5083 in hydroforming process is simulated using commercially available finite element software, and three different constant pressures through which the applied pressure effects on important parameters such as thickness distribution, final dome height, and distributions of equivalent stress and strain are evaluated.
Patent•
24 Jul 2008TL;DR: In this article, a tubular torsion beam for rear suspensions of vehicles is presented, which is produced according to a more durable design capable of improving roll stiffness and roll strength of the beam.
Abstract: The present invention provides a tubular torsion beam for rear suspensions of vehicles, which is produced according to a more durable design capable of improving roll stiffness and roll strength of the tubular torsion beam. The tubular torsion beam is produced by pressure-forming a tubular steel member through hydroforming such that the tubular torsion beam has a cross-section varying along an entire length thereof, with opposite ends having a closed cross-section and mounted to respective trailing arms, a middle portion having a V-shaped open cross-section, and a transitional portion having a varying cross-section and connecting the middle portion to each of the opposite ends. During the process of manufacturing the tubular torsion beam, the opposite ends of the tubular steel member are fed using respective axial punches of a hydroforming machine, so that the opposite ends are thicker than the middle portion.
01 Sep 2008
TL;DR: In this article, the effect of oscillations in the internal pressure on tube wall thickness and die corner filling in the pulsating hydroforming of T-shape tubes was examined using finite element simulation and experiments.
Abstract: The effect of oscillations in the internal pressure on tube wall thickness and die corner filling in the pulsating hydroforming of T-shape tubes is examined using finite element simulation and experiments. The thinning behaviour of the tube during the pulsating hydroforming is studied for different coefficients of friction to investigate the mechanism of the improvement in formability. It is shown that the thinning behaviour is similar for different friction conditions. It is also illustrated that the pulsating pressure improves the formability, even for frictionless tube hydroforming. Thus, the reason for the improvement in the formability may not be due to a reduction in the friction level. In addition, the effects of the amplitude and frequency of the pulsating pressure on the thinning behaviour of tubes and die corner filling are examined. It is shown that, while a small number of cycles and a large amplitude of the pulsating pressure decrease the filling ratio of the die corner, they are more effecti...
TL;DR: In this article, the authors describe tube hydroforming is gaining increasing interest from the metal forming industry and describe complicated parts with a high level of structural component integration, e.g. engine cradles, subframes and exhaust manifolds.
TL;DR: In this article, analytical and numerical forming limit predictions are studied from a hydroforming point of view, and these predictions are then applied to free bulge cases, and a case with extensive feeding in a die where the results from the latter case is compared to experiments.
TL;DR: In this article, the feasibility of combining joining by forming processes and adhesives for joining of tubular workpieces made of identical material is investigated, where the authors consider the problem of joining of identical materials, which is a current research project within the scope of SFB/Transregio 10.
Abstract: Joints which are solely produced by forming processes are capable of transmitting e.g. axial loads by means of dominating force- (alternatively named interference) or form-fit. Furthermore, a transmission of load could be directed by a combination of both and with supporting adhesives. Joining by forming has been done by compressing tubes using external rolling and electromagnetic forming; joining by expansion has been performed by dieless hydroforming and rolling. Moreover, a problematic constraint for joining by expansion or compression, namely joining of identical materials, which is a topic of a current research project within the scope of SFB/Transregio 10, has to be taken into account. Consequently, the article focuses on the feasibility of combining joining by forming processes and adhesives for joining of tubular workpieces made of identical material (EN-AW6060F22). Resisting loads of form- and force-fit joints have been taken as a reference.
TL;DR: The forming test proved a good shape accuracy of the sheet metal parts but revealed critical tribological conditions, and a special mixture of UHPC for these tools with its mechanical properties and its manufacturing is presented.
Abstract: The paper concentrates on investigation results dealing with ultra high performance concrete (UHPC) dies for the use in sheet metal hydroforming. A special mixture of UHPC for these tools with its mechanical properties and its manufacturing is presented. The developed UHPC features a compressive strength of approx. 250 MPa and a Young’s modulus of approx. 50 GPa. Applying internal pressure, the UHPC die (without confinement or reinforcement) failed between 80 and 96 MPa. The forming test proved a good shape accuracy of the sheet metal parts but revealed critical tribological conditions. Drawing foil and already formed sheet metal parts were tested successfully as interlayer and led to an appropriate material flow and surface quality of the sheet metal parts.
TL;DR: Choi et al. as discussed by the authors proposed an adaptive-isothermal finite element analysis (FEA) and a design of experiment (DOE) approach to determine the optimal temperature condition in a warm hydroforming system accurately and rapidly.
Abstract: Hydroforming of lightweight materials at elevated temperature is a relatively new process with promises of increased formability at low internal pressure levels In this study, the mechanism of warm hydroforming processes is presented in terms of its formability by comparison with warm forming, and cold hydroforming processes Additionally, a strategy is proposed to control process parameters, such as temperature, hydraulic pressure, blank holder force, and forming speed As a part of this strategy, the proper temperature condition is determined by adaptive-isothermal finite element analysis (FEA) and a design of experiment (DOE) approach The adaptive-isothermal FEA determines the temperature levels of the blank material, which is selectively heated, by checking position of the blank material and adopting temperature level of the neighboring tooling The proposed adaptive-isothermal FEA/DOE approach leads to the optimal temperature condition in a warm hydroforming system accurately and rapidly as opposed to costly and lengthy experimental trial and errors and/or fully coupled thermo-mechanical simulations Other process parameters are also optimized in a continued study (Choi et al, 2007, “Determination of Optimal Loading Profiles in Warm Hydroforming of Lightweight Materials,” J Mater Process Techn, 190(1‐3), pp 230‐242) DOI: 101115/12951945
TL;DR: In this article, the numerical simulation of the tubular metallic components, tailor-welded before forming, is presented, focusing on the influence of process parameters, such as the position of the weld-line and initial thickness values, in the innovative process of combining tailor welded tubes (with distinct thickness values) and hydroforming.
Abstract: Developments in the numerical simulation of the hydroforming process of tubular metallic components, tailor-welded before forming, are presented. Both technologies, tailor-welded joining operations and hydroforming processes, are well known in industry, although most commonly separately used. Tailor-welded joining operations are usually encountered in plain sheets, subsequently formed by stamping. Tube hydroforming processing, on the other hand, is frequently associated with parts consisting of uniform thickness, material properties, and dimensions. The present analysis focuses on the influence of process parameters, such as the position of the weld-line and initial thickness values, in the innovative process of combining tailor-welded tubes (with distinct thickness values) and hydroforming. Particular attention is posed on the relation of imposed axial displacement vs. imposed hydraulic pressure into the tube, forming parameters that are not known a-priori in the manufacturing of a new part. Another point of practical interest is the numerical simulation of the weld-line movement, after forming is complete. The finite element method is directly employed in the numerical simulation by means of innovative solid elements suited for incompressibility applications, and included by the authors into the commercial program ABAQUS as user-elements. The obtained results can then lead to a better understanding, along with design tools, for the process of hydroforming of tailor-welded tubular parts, accounting for dissimilar thickness of the basic components.
TL;DR: Based on the proposed multi-operation hydroforming with the non-uniform blank holding pressure unit, using the poor formability materials including aluminum alloy and high-strength steel alloy, the effects of key process parameters including the shape of pre-forming punch, preforming depth, blank shape and cavity pressure, punch movement on the finally formed parts were discussed as mentioned in this paper.
TL;DR: In this paper, the feasibility of joining by forming has been carried out investigating experimentally both conventionally extruded and reinforced profiles, and the necessary forming pressure for the joining-by-forming processes was applied to tubular workpieces by a medium (hydroforming) and by a magnetic field (electromagnetic compression).
Abstract: One major objective of the Collaborative Research Center SFB/TR10 is the flexible and competitive production of frame structures which meet the requirements of lightweight design. The development of composite extrusion by embedding continuous reinforcing elements, like e.g. steel wires, in profiles during the extrusion process illustrates one approach to fulfill these conditions. To assemble such composite profiles, joining processes and strategies have to be developed taking into account the special composite material characteristics. In addition, the flexible production of lightweight frame structures in small quantities generates more requirements on the joining technology. The feasibility of joining by forming has been carried out investigating experimentally both conventionally extruded and reinforced profiles. Therefore, joining profiles to lightweight frame structures by both expansion and compression has been examined. The necessary forming pressure for the joining by forming processes was applied to tubular workpieces by a medium (hydroforming) and by a magnetic field (electromagnetic compression). Joints have been manufactured by these two processes to transmit axial loads either by force- or form-fit.
TL;DR: In this article, the application of intrusion bending method to tubes with extremely low ratios of wall thickness to outer diameter (from 1.2 to 1.9%), and whose steel grades are SSPDX, SAFC440R, and SAFC590T was investigated.
Abstract: In regard to light-weight structural members for automobiles, attention to hydroforming has been increasing. Intrusion-bending method is well suited to the preliminary bending of hydroformed structural members of automobiles, because straight tubes can be bent into three-dimensional forms by this new method. However, in the case of tubes with a thin wall thickness, wrinkling remains a problem. In this report, application of intrusion bending method to tubes with extremely low ratios of wall thickness to outer diameter (from 1.2 to 1.9%), and whose steel grades are SSPDX, SAFC440R, and SAFC590T was investigated. A summary of this study is as follows. Effects of steel grades and wall thickness ratios on wrinkle formation, eccentricity, and ovality are studied. Relationships between wrinkle generation and gyro movement are investigated.
TL;DR: In this paper, the authors investigated the prediction of forming limit diagrams (FLDs) for tube hydroforming from the perspective of selecting various combinations of loading parameters based on plastic instability.
TL;DR: In this paper, an analytical model of the guiding zone tribotest commonly used to evaluate lubricant performance for tube hydroforming is presented, which can aid as a quick tool for iterating geometric variables in the design of a guiding zone.
Abstract: Common part failures in tube hydroforming include wrinkling, premature fracture, and unacceptable part surface quality. Some of these failures are attributed to the inability to optimize tribological conditions. There has been an increasing demand for the development of effective lubricants for tube hydroforming, due to widespread application of this process. This paper presents an analytical model of the guiding zone tribotest commonly used to evaluate lubricant performance for tube hydroforming. Through a mechanistic approach, a closed-form solution for the field variables contact pressure, effective stress/strain, longitudinal stress/strain, and hoop stress can be computed. The analytical model was validated by the finite element method. In addition to determining friction coefficient, the expression for local state of stress and strain on the tube provides an opportunity for in-depth study of the behavior of lubricant and associated lubrication mechanisms. The model can aid as a quick tool for iterating geometric variables in the design of a guiding zone, which is an integral part of tube hydroforming tooling.Copyright © 2008 by ASME
TL;DR: In this article, dual phase steel tubes were produced using a novel processing sequence, where a ferrite/pearlite sheet is formed into steel tubes, which are then normalized, induction heated to an intercritical temperature, quenched, and tempered, producing a dual phase microstructure.
TL;DR: Simha et al. as discussed by the authors derived upper and lower bound strain-based forming limit curves for tubular hydroforming of high strength low alloy (HSLA) and dual phase (DP600) straight tubes.