Sheet Hydroforming Process Research Articles

A 3D Non-Linear FE Model and Optimization of Cavity Die Sheet Hydroforming Process

Cryo-rolled aluminum alloys have a much higher strength-to-weight ratio than cold-rolled alloys, which makes them invaluable in the aerospace and automotive industries. However, this strength gain is frequently accompanied by a formability loss. When uniformly applied to the blank surface, hydroforming provides a solution by generating geometries with constant thickness, making it possible to produce complex structures with “near-net dimensions”, which are difficult to achieve with conventional approaches. This study delves into the cavity die sheet hydroforming (CDSHF) process for high-strength cryo-rolled AA5083 aluminum alloy, focusing on two primary research questions. Firstly, we explored the utilization of a nonlinear 3D finite-element (FE) model to understand its impact on the dimensional accuracy of hydroformed components within the CDSHF process. Specifically, we investigated how decreasing fluid pressure and increasing the holding time of peak fluid pressure can be quantitatively assessed. Secondly, we delved into the optimization of process parameters—fluid pressure (FP), blank holding force (BHF), coefficient of friction (CoF), and flange radius (FR)—to achieve dimensional accuracy in hydroformed square cups through the CDSHF process. Our findings reveal that our efforts, such as reducing peak fluid pressure to 22 MPa, implementing a 30 s holding period, and utilizing an unloading path, enhanced component quality. We demonstrated this with a 35 mm deep square cup exhibiting a 16.1 mm corner radius and reduced material thinning to 5.5%. Leveraging a sophisticated nonlinear 3D FE model coupled with response surface methodology (RSM) and multi-objective optimization techniques, we systematically identified the optimal process configurations, accounting for parameter interactions. Our results underscore the quantitative efficacy of these optimization strategies, as the optimized RSM model closely aligns with finite-element (FE) simulation results, predicting a thinning percentage of 5.27 and a corner radius of 18.64 mm. Overall, our study provides valuable insights into enhancing dimensional accuracy and process optimization in CDSHF, with far-reaching implications for advancing metal-forming technologies.

Investigation of the effect of process parameters in sheet hydroforming process

Investigation of the effect of process parameters in sheet hydroforming process

Studies on Finite Element Analysis in Hydroforming of Nimonic 90 Sheet

The primary goal of this study was to investigate the formability of Nimonic 90 sheet which performs well at high temperatures and pressures, making it ideal for applications in the aerospace, processing, and manufacturing industries. In this present study, finite element analysis (FEA) and optimization of process parameters for formability of Nimonic 90 in sheet hydroforming were investigated. The material’s mechanical properties were obtained by uniaxial tensile tests as per the standard ASTM E8/E8M. The sheet hydroforming process was first simulated to obtain maximum pressure (53.46 MPa) using the FEA and was then validated using an experiment. The maximum pressure obtained was 50.5 MPa in experimentation. Since fully experimental or simulation designs are impractical, the Box–Behnken design (BBD) was used to investigate various process parameters. Formability was measured by the forming limit diagram (FLD) and maximum deformation achieved without failure. Analysis of variance (ANOVA) results also revealed that pressure and thickness were the most effective parameters for achieving maximum deformation without failure. Response surface methodology (RSM) optimizer was used to predict optimized process parameter to achieve maximized response (deformation) without failure. Experimental validation was carried out for the optimized parameters. The percentage of error between experimental and simulation results for maximum deformation was less than 5%. The findings revealed that all the aspects in the presented regression model and FEM simulation were effective on response values.

Microstructural analysis of sheet hydroforming process assisted by radial ultrasonic punch vibration in a hydro-mechanical deep drawing die

Microstructural analysis of sheet hydroforming process assisted by radial ultrasonic punch vibration in a hydro-mechanical deep drawing die

Punch-less and die-less sheet hydroforming process for manufacturing of serpentine-shaped micro-channels in ultra-thin sheets

In the present work, novel serpentine-shaped micro-channels were successfully fabricated in ultra-thin sheets of AA1050, C101, and SS304 materials using the sheet hydroforming (SHF) process. In-house fabrication methods, namely punch-less SHF and die-less SHF processes were designed and developed on a 20-t press to manufacture these channels. The finite element (FE) modeling of both processes was developed for the prediction of the deformation behavior of these sheets. The elasto-plastic FE models incorporated the elastic properties, Barlat 89 anisotropic yield model, and Hollomon hardening law for all the three sheets, and their corresponding forming limit diagrams (FLDs) were implemented as damage criteria. It was observed that the maximum pressure was 28 MPa and 32 MPa for the punch-less and die-less SHF process, respectively. The manufacturability of the hydroformed channels was examined through channel depth, aspect ratio, and thickness distribution. The average channel depth and aspect ratio were found to be higher in the case of the die-less SHF compared to punch-less SHF. The failure occurred in the AA1050 channel under plane strain deformation mode near the die corner region and punch corner region for punch-less and die-less SHF processes, respectively, indicated by a sudden dip in the thickness distribution profile. Moreover, the surface quality of the formed channels was investigated through surface roughness value, and this was further correlated with effective plastic strain incurred in the deformation process. It was observed that the surface roughness of the deformed channels fabricated by the punch-less SHF process was lower than those formed through the die-less SHF process in the present study.

Deformation of large curved shells using double-sided pressure sheet hydroforming process

Large, thin-walled, and curved surface shells are challenging to deform using traditional forming technologies owing to wrinkling and rupture defects that coexist during the deformation process. In this study, the process of double-sided pressure sheet hydroforming (DSHF) was developed to overcome these issues and fabricate large curved components integrally. A theoretical analysis model was established by considering the stress and strain distributions at varying double-sided pressure ratios during DSHF. Simulations and experiments were conducted using the DSHF process on a hemispherical shell to analyse the effects of the pressure ratio on deformation behaviour, stress and strain, thickness distribution, and deformation defects. Furthermore, a phenomenon called “planar deformation state” was observed, and the stress state was optimised by setting a proper pressure ratio. Under this condition, the thickness distribution was improved and the formed curved shells were free from wrinkling and rupture defects. A CNC sheet hydroforming machine developed by Harbin Institute of Technology was employed to perform a case study of the DSHF process. Lastly, to demonstrate the application of the proposed process, an aluminium-alloy dome with a diameter of 3 m and a uniform thickness distribution was fabricated.

DIE SHEET HYDROFORMING OF A COMPLEX-SHAPED AA2024-W AIRCRAFT SKIN PANEL — FROM CONCEPT TO FINAL COMPONENT

Product design in the early stages requires a more quantitative process to ensure that the simulation study's outcome will meet expectations. The purpose of this study was to determine whether a manufacturing simulation software package could effectively evaluate and validate the conceptualised blank and tooling to manufacture a sizeable complex- shaped aluminium alloy aircraft panel using die sheet hydroforming. Blank and tool concepts were conceptualised, evaluated, and validated digitally using the forming process conceptualisation cycle. Without the need to trial several blank and tool concepts physically, a significant saving was achieved using a resource-efficient development process. Even without modelling the hyperelastic rubber elements, a successful die sheet hydroformed simulation result was conducted. However, the study showed that a rubber-to-metal friction coefficient must be incorporated appropriately. The study further showed the lack of standard metrology methods in commercial simulation packages to evaluate a simulation result accurately. Simulation metrology is a new area of interest that requires further development. This research contributes to improving the sheet metal forming simulation process and, specifically, die sheet hydroforming process simulation. The study will benefit the aerospace and automotive industry and promote the adoption of digital manufacturing processes.

Evolution of Hydroforming Technologies and Its Applications — A Review

Advanced forming technologies have been evolving at a rapid pace with the products applicability in the industrial fields of aerospace and automobile especially for the materials like aluminum and titanium alloys (light weight) and ultra-high strength steels. Innovative forming methods like hydroforming (tube and sheet) have been proposed for industries throughout the world. The ever-increasing needs of the automotive industry have made hydroforming technology an impetus one for the development and innovations. In this paper, the review on various developments towards lightweight materials for different applications is presented. The influencing process parameters considering the different characteristics of the tube and sheet hydroforming process have also been presented. General ideas and mechanical improvements in sheet and tube hydroforming are given late innovative work exercises. This review will help researchers and industrialists about the history, state of the art in hydroforming technologies of the lightweight materials.

Investigation of Hydroforming Technology for Manufacturing an Auto Complex Part

Hydroforming process is used for obtaining different kinds of sheet metal components in an economic manner in terms of time and costs reduction and increase of the product quality. This paper deals with the application of this type of technology for manufacturing a rotational auto part from aluminium alloy. An experimental tool for hydroforming with rubber membrane was used. A set of dies with different geometries has been designed and constructed. Experiments have been conducted for investigation the ability of transferring features from the die onto the blank surface for different die geometries and pressures. The hydroformed part was measured using CMM. Based on the experimental data a numerical model was designed. FEM using Abaqus solver was used for investigated the part geometry and the effective stress distribution under various pressures conditions and dies geometries. The experimental and simulation results show the feasibility of applying the sheet hydroforming process in order to obtain a sound product.

Enabling sheet hydroforming to produce smaller radii on aerospace nickel alloys

This paper presents the first academic study of a hydroforming process known as edging. An edging process allows a smaller radius to be produced with a lower pressure than a standard sheet hydroforming process and is currently developed by trial and error that relies heavily on operator experience. This paper reports the first systematic investigation of the edging process that concludes in a new analytical model which can be used to enable the design of edging processes. It was found that in each of the three aerospace nickel alloys tested, the edging technique was effective in sharpening the flange radius from 10 mm to 4 mm or from 6 mm to 2 mm in thicknesses of 2.1 mm and 1.2 mm respectively. This radius is equivalent to between 1.5 and 1.8 times the material thickness (1.5 t to 1.8 t). These results were achieved by using edging heights of between 2.5 to 5 mm (2.5 t to 3 t). At the limits of successful edging operations, (under 2 t) three different kinds of phenomena were observed: crushing of the top of the component, radii which were pushed inwards, and the generation of an underside lip which protruded from the bottom of the samples. This paper discusses the benefits of hydroforming with an edging operation, explores the limitations of the edging process, derives an equation which can be used to estimate the sharpness of an edged radius and finally defines a model which enables the design of an edging operation. The work reported here is particularly relevant to aerospace applications because it will enable lighter components to be formed with lower pressures with nickel based superalloys.

Enhancement on plastic deformation of curved surface shell by sheet hydroforming with optimized pre-bulging process

For sheet metal components, the enhancement of formability during plastic deformation is a key criterion in the evaluation of forming quality. To realize homogenous deformation during the forming of curved surface shells, a pre-bulging process combined with sheet hydroforming technology was designed. The pre-bulging shape was optimized using response surface methodology. An experimental setup was manufactured to conduct pre-bulging and sheet hydroforming process. The distribution of strain and thickness were measured to present the formability of the parts. The stress distribution was calculated to analyze the deformation mechanism. Results show that when using appropriate pre-bulging and sheet hydroforming process, the average strain value and uniform deformation parameter can be improved simultaneously. The microhardness of formed shell is increased. The stress state in the center region after pre-bulging is changed to biaxial compression state. It can be concluded that the combination between optimized pre-bulging effect and sheet hydroforming process is a potential method for the enhancement of formability including deformation value and uniformity.

Evaluation of numerical and experimental investigations on the hybrid sheet hydroforming process to produce a novel high-capacity engine oil pan

The engine oil pan is used for restraining pollutant and gathering greasing oil from the engine components’ surface which is significant for thermal dissipation and preventing deterioration of oil quality. The study intended to investigate and develop a hybrid sheet hydroforming process for fabricating an innovative high-capacity oil pan that has the characters of asymmetrical cavity depth and major lateral bulging. Firstly, a two-stage hydromechanical deep drawing (HMDD) process was accomplished, which included precedingly regional and eventually integral deep drawing assisted by fluid counter force. The finite element modeling (FEM) was employed to study the impact of the die fillet dimension as well as the loading routes on the formability of the preformed part. The limited drawing ratio can be enhanced from 2.34 to 2.77 for AISI 304 by HMDD. Hydro-bulging was subsequently investigated by the simulations accompanied by the relatively experimental verification. Both the simulated and experimental results showed that there is a remarkable influence of lubrication condition and intermediate heat treatment on the formability of the final part. The cracks occurred at the corners of the main bulging area can be alleviated by reduction of friction coefficient. Furthermore, wrinkles and cracks have been completely eliminated and the thinning ratio can be reduced to 31.8% for the final part, when intermediate heat treatment is additionally employed. It was concluded that the present hybrid sheet hydroforming process is feasible and sufficient to manufacture a sound engine oil pan without any defects through the optimization of the process parameters.

Application of a new integrated optimization approach in sheet hydroforming process

The purpose of this study is to produce a desired hydroformed product under the optimal pressure profile. To achieve this purpose, a new adaptive optimization approach is proposed based on fuzzy logic control (FLC) integrated with simulated annealing (SA) optimization technique and ANSYS parametric design language (APDL). An intermediate MATLAB code was developed and used to manage data transfer automatically between FLC, SA and APDL, in which there would be no need for any interaction of user/designer during the optimization process execution. This method aims to find the optimal pressure loading profile, prevent wrinkling and necking failures, reduce unsuccessful iterations, and enhance convergence precision. This method is capable of adaptively changing the process parameters in order to reach the optimized values with higher accuracy in a more reasonable time. The results show a good agreement between the proposed optimization approach and experiments. The developed optimization approach is a practical and reliable design tool for industrial production of any symmetric shell cups using hydroforming process.

Numerical Analysis of Rubber Assisted Sheet Hydro-Forming Process and its Experimental Verification

Numerical Analysis of Rubber Assisted Sheet Hydro-Forming Process and its Experimental Verification

Investigation of Forming Cylindrical Parts in a Modified Hydrodynamic Deep Drawing Assisted by Radial Pressure With Inward Flowing Liquid

Among the sheet hydroforming processes, hydrodynamic deep drawing (HDD) process has been used to form complex shapes and can produce parts with high drawing ratio. Studies showed that radial pressure created on the edge of the sheet can decrease the drawing force and increase drawing ratio. Thus, increasing of radial pressure to an amount greater than chamber pressure, and independent control of these pressures, is the basic idea in this study. In this research, the effect of radial and chamber pressures on formability of St13 and pure copper sheets in the process of hydrodynamic deep drawing assisted by radial pressure (HDDRP) with inward flowing liquid is investigated. Giving that a significant portion of the maximum thinning of the formed part occurs in the beginning of the process, the pressure supply system used in the experimental tests was designed in a way, which provides simultaneous control of the radial and chamber pressures throughout the process. Thickness distribution, forming force, and tensile stresses are the parameters that were evaluated in this study. Results indicated that using a higher radial pressure than the chamber pressure and controlling their values in the initial stages of the process enhances the thickness distribution of the formed part in all regions. A comparison between the thickness distribution and maximum forming force of the formed parts by the HDDRP and HDDRP with inward flowing liquid methods showed that by applying the later method, parts with more uniform thickness distribution and less maximum thinning and forming force can be achieved.

Quick establishment of backpressure path in sheet hydroforming process

Backpressure path is a vital parameter for the control of dimensional accuracy and shape integrity of the fabricated part and the improvement of material formability in sheet hydroforming. The optimal backpressure path is closely related to the unsupported wall region between the punch and the die, which is determined by the geometric characteristic of the fabricated part. To clarify the relation between the optimal backpressure path and part feature, the workpieces are classified into three types according to the various change patterns of the unsupported area during the hydroforming deformation. To establish the correlation of unsupported region with the reasonable loading locus, three different types of workpieces including a cylindrical part with constant unsupported area, a conical part owning continuous variable noncontact region and an irregular part with composite vacant area were selected to be produced via sheet hydroforming. The forming quality of the three parts was analyzed under different backpressure loci, and the relationship between the optimal backpressure path and the unsupported region was built.

Determination of critical pressure in analyzing of rupture instability for hydromechanical deep drawing using advanced yield criterion

Hydromechanical deep drawing (HMDD) is a sheet hydroforming process to produce complex workpieces with high drawing ratio. Fluid pressure used during the forming process is one of the most effective parameters in this process in which increasing critical pressure causes to rupture occurrence. Since the material properties in different angles respect to the rolling direction affect the amount of critical pressure, it is important to develop an appropriate theoretical model for prediction of plastic behavior of material with high precision. In this paper, a theoretical model based on BBC2008 yield criterion including 8 and 16 parameters (8p and 16p) is developed to determine critical pressure in HMDD process. With applying uniaxial and equi-biaxial tensile tests and optimizing an error-function by using Levenberg–Marquardt method, the parameters of BBC2008 yield criterion can be determined. Low carbon St14 steel sheets are utilized for experimental samples to verify critical pressure obtained from the proposed theoretical model. BBC2008 model with 8p and 16p is compared with Barlat–Lian 1989 and experiments. The results show that BBC2008-16p yield criterion can provide a more precise model of material behavior in planar anisotropy properties, while BBC2008-8p yield criterion have a better prediction of rupture occurrence in HMDD process.

Influence Law of Initial Reverse Bulging on Sheet Hydroforming Process

In order to investigating the effect of the combination of two technological parameters such as the initial bulging height and the initial bulging pressure on the sheet , the sheet hydroforming process was studied. Firstly, by using the method of numerical simulation, the sheet hydroforming process with and without the initial bulging were discussed; Secondly, the effect of both the initial bulging height and the initial bulging pressure which were based on the hydroforming with the initial bulging on the forming of the part was studied; Thirdly, the result of the simulation was verified in the experiment. It was found that when the initial bulging height is 3.75mm and the initial bulging pressure is 2MPa, the maximum thinning ratio of the sheet is 4.803% at the end of the sheet hydroforming process. According to the hydroforming process without the initial bulging factors, the maximum thinning ratio is 5.123%. It can be found that the initial bulging factors play a key role in the sheet hydroforming process. The maximum thinning ratio of the wall thickness can be decreased effectively by the appropriate initial bulging height and bulging pressure, and the forming limit can also be improved at the same time. The results of numerical simulation have a reasonable agreement with the experimental results.

A new simulation-based metaheuristic approach in optimization of bilayer composite sheet hydroforming

Simulated annealing which has been recently used in engineering applications is one of the most popular metaheuristic algorithms to solve optimization problems. In this work, an adaptive simulated annealing (SA) technique coupled with an adaptive finite element method is proposed and developed to optimize bilayer composite sheet hydroforming process. The aim of this combinatorial procedure is to obtain optimal forming pressure loading path to develop a new definition of SA algorithm parameters, to create an adaptive finite element (FE) code, to produce desired products with minimum thinning, and to avoid wrinkling and bursting failures. All of the effective SA parameters including Markov chain number, cooling function, initial temperature, and final temperature are redefined and developed to reduce excess iterations in FE simulations, hence saving the time and energy during the optimization process. The proposed optimization technique is employed to investigate the effect of layers sequence and thickness ratio on minimum cup thinning and optimal pressure load in hydroforming of aluminum/steel composite sheet. The experimental results demonstrated that the proposed adaptive method could be a reliable technique for optimization of processes with a large search space. It is also shown that it provides precise results in a shorter time by redefining the algorithm parameters.

Process window calculation and pressure locus optimization in hydroforming of conical box with double concave cavities

With the enhancement in the functional integration of components and concentration on lightweight materials, complex sheet metal parts are widely used in automobile and aviation industrial clusters. Consequently, the sheet hydroforming process has become an attractive fabricating technology for forming lightweight materials and complicated products. In this research, the hydrodynamic deep drawing (HDD) process of a composite conical box with double concave cavities was investigated through theoretical analysis, numerical simulation, and process experimentation. Furthermore, the process window diagram (PWD) was calculated using the stress analytical model combining material properties with workpiece geometrical features. The influence of cavity pressure loading locus on the forming quality of the fabricated part and the deformation behavior of aluminum alloy was explored. The forming results indicated that the initial pressure, full pressure, and loading locus are the fundamental parameters directly related to the forming quality and dimensional accuracy. For the conical part with composite features, the reasonable initial pressure value is crucial for the thickness homogeneity of the double concave characteristics, whereas the magnitude of the full pressure is vital for improving the quality of the conical feature. In addition, the optimal loading locus of the cavity pressure is characterized by two turning points, which are related to the punch corner radius, die shoulder radius, blank thickness, and angle of the conical feature.