冷弯成形过程的数值模拟英文文献和中文翻译
One must thereforetry to reduce tooling costs without compromising the sectionquality.Industrial practice largely relies on empiricismand heuris-tic rules for the design of roll-forming.Unfortunately, there arefewdesign rules that are universally accepted, since thewholedesign process of roll-forming is rather subjective. Workshoptests using a trial-and-error method is the common practicebut it inevitably requires a large amount ofmaterial and time.Under such circumstances, numerical simulation appears tobe an attractive alternative, since it allows reducing the timenecessary for roll pass design of new products.Different approaches have been proposed for the mod-elling of the forming process. Based on a hypotheticaldeformed sheet surface; i.e. a predefined geometry, simplifiedapproaches, which do not require an important effort of com-putation, can be developed. For example, Kiuchi (1973) have suggested a sinusoidal “shape function” to describe themiddlesheet surface between the roll stands for the formation of a cir-cular section. Alternatively, Nefussi and Gilormini (1993) havepreferred a Coons patch technique for the middle deformedsheet surface. Towards a more practical solution, which canbe applied for complex sections, the finite element methodhas recently obtained increasing attention in the simulationof cold roll-forming process. From the assumption on contin-uously moving rigid surfaces between two stations, Brunet etal. (1996) have proposed an elastic–plastic finite element tech-nique,where a 2D plane stress analysiswithmoving boundaryconditions is combined with a 3D shell analysis. On the otherhand, a combined 2D and 3D analysis has also been employedby Hong et al. (2001), where the assumption of a uniform ofstrain-rate over the cross section was adopted. For a morerealistic prediction and at the expense of increasing computa-tional effort, a 3D analysis has been attempted by (Heislitz etal., 1996) in the prediction of strain distributions, sheet geom-etry during and after the forming process. Besides the finiteelementmethod, the finite stripmethod has also been appliedfor the study of roll-forming process (Han et al., 2002).In this study, based on an in-house software namedMetafor (Ponthot, 1995), 3D-finite element simulation will beused to analyse the cold forming process. Our attention ismainly paid to the development of strains, which is likely ameasure of forming severity and potential forming problems.Indeed, if the legs of a profile are bent step-by-step from onestand to another, the edges travel a longerway than theweb ofthe profile. This leads to higher values of strains and stressesin the edges.