Process Analysis and Design in Stamping and Sheet Hydroforming

 
 
 
 

Process Analysis and Design in Stamping and Sheet Hydroforming

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dc.contributor.advisor Altan, Taylan en_US
dc.contributor.author Yadav, Ajay D. en_US
dc.date.accessioned 2009-04-10T06:50:35Z
dc.date.available 2009-04-10T06:50:35Z
dc.date.created 2008 en_US
dc.date.issued 2009-04-10T06:50:35Z
dc.identifier.uri http://rave.ohiolink.edu/etdc/view?acc_num=osu1210952822 en_US
dc.identifier.uri http://hdl.handle.net/2374.OX/107526
dc.description This thesis presents initial attempts to simulate the sheet hydroforming process using Finite Element (FE) methods. Sheet hydroforming with punch (SHF-P) process offers great potential for low and medium volume production, especially for forming (a) lightweight materials such as Al- and Mg- alloys and (b) thin gage high strength steels (HSS). Sheet hydroforming has found limited applications and is thus still a relatively new forming process. Therefore, there is very little experience-based knowledge of process parameters (namely forming pressure, blank holder tonnage) and tool design in sheet hydroforming. For wide application of this technology, a design methodology to implement a robust SHF-P process needs to be developed. There is a need for a fundamental understanding of the influence of process and tool design variables on hydroformed part quality. This thesis addresses issues unique to sheet hydroforming technology, namely, (a) selection of forming (pot) pressure, (b) excessive sheet bulging and tearing at large forming pressures, and (c) methods to avoid leaking of pressurizing medium during forming. Through process simulation and collaborative efforts with an industrial sponsor, the influence of process and tool design variables on part quality in SHF-P of axisymmetric punch shapes (cylindrical and conical punch) is investigated. In stamping and sheet hydroforming, variation in incoming sheet coil properties is a common problem for stamping plants, especially with (a) newer light weight materials for automotive applications (aluminum-, magnesium- alloys) and (b) thin gage high strength steels. Even though incoming sheet coil may meet tensile test specifications, high scrap rate is often observed in production due to inconsistent material behavior. Thus, tensile test specifications may not be adequate to characterize sheet material behavior in production stamping/hydroforming operations. There is a strong need for a discriminating method for testing incoming sheet material formability. The sheet bulge test emulates biaxial deformation conditions commonly seen in production operations. This test is increasingly being applied by the European automotive industry, especially for obtaining reliable sheet material flow stress data that is essential for accurate process simulation. This thesis presents a new 'inverse-analysis' methodology for calculating flow stress curves at room temperature, using the biaxial sheet bulge test. This approach overcomes limitations of previously used closed-form membrane theory equations and exhibits great potential for elevated temperature bulge test application. To verify the developed methodologies presented in this thesis, selected case studies are presented, to (a) demonstrate the successful application of finite element (FE) simulation in tool design, process sequence design and springback reduction in stamping and sheet hydroforming and, (b) validate the developed methodology for automation/standardization of tool and process sequence design procedure and recording of existing design guidelines in transfer die stamping. en_US
dc.format application/pdf en_US
dc.format 251p. en_US
dc.rights unrestricted en_US
dc.rights Copyright and permissions information available at the source archive en_US
dc.subject sheet metal forming en_US
dc.subject sheet hydroforming en_US
dc.subject process simulation en_US
dc.subject material characterization en_US
dc.title Process Analysis and Design in Stamping and Sheet Hydroforming en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name PhD en_US
dc.degree.level doctoral en_US
dc.degree.discipline Industrial and Systems Engineering en_US
dc.degree.grantor Ohio State University en_US
dc.contributor.publisher Ohio State University / OhioLINK en_US

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