Contribution au développement d'une approche simplifiée de la simulation numérique du formage incrémental

Abstract : The incremental sheet forming (ISF) is an innovative process in sheet metal forming method by using a hemispherical rigid tool controlled by Computerized Numerical Control machine (CNC). The clamped sheet is locally deformed following a tool path, defining thus the final geometry of the part. The advantages of this method are its high flexibility, its low tooling cost, and its ability to shorten the design and manufacturing chain. The application of the reduction of the overall costs, and development time made the numerical simulation essential. Many robust simulation models based on the finite element method enable to predict the formability and the geometrical quality of the part. Classic algorithms of simulation ensure reliable quality results but necessary computation times (CPU) are still very long. In this context, a Simplified Approach has been developed to reduce the computation time. This approach allows avoiding the integration of the tool and its contact with the sheet into the numerical simulation, by replacing them with a local and progressive displacement imposition of certain nodes supposed to be in contact with the tool. A complementary solution is proposed within this thesis to reduce the CPU times of a simulation sequence, by using a shell element called DKTRF (Discrete Kirchhoff Triangle Rotation Free). This element takes account of the membrane and bending effects with restricted numbers of degrees of freedom, as the flexion terms are defined in accordance with the nodal translational displacements of the adjacent elements. The integration of this element combined with the Simplified Approach for a regular mesh in an elastoplastic problem gives consistent outcomes in geometric and behavioural, with significant diminution of CPU times in comparison with the industrial numerical simulation performed on ABAQUS©. Results obtained by means of numerical simulation of a study case are then compared with experimental results, thereby enabling to validate the model and to study the influences of process parameters on the final piece. To do this, an experimental test procedure is developed in order to evaluate the efficiency of incremental forming process on a Computerized Numerical Control machine (CNC). The measurement technique used to characterize the geometry (thickness and profile) of the piece is the scanning method. The measurement tool, transcribed accurately the geometry of the part via cameras and post-treatment software. Particularly well-suited for the assessment of the profile, the acquisition method remains to be optimize especially for assessing the thickness of the sheet
Document type :
Theses
Complete list of metadatas

Cited literature [16 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01751222
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 1:11:30 PM
Last modification on : Tuesday, April 10, 2018 - 1:27:22 AM

File

DDOC_T_2014_0227_YU.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01751222, version 1

Collections

Citation

Yan Yu. Contribution au développement d'une approche simplifiée de la simulation numérique du formage incrémental. Autre. Université de Lorraine, 2014. Français. ⟨NNT : 2014LORR0227⟩. ⟨tel-01751222⟩

Share

Metrics

Record views

72

Files downloads

36