Numerical analysis of displacement and stress fields of off-axis composites in three-point flexure

Abstract

Three-point flexure test for unidirectional off-axis composites has been analyzed by the finite element method. The main difficulty of modeling three-point flexure test of this kind of material is due to the bending-twisting coupling that induces the lift-off of the specimen at the fixture supports. In the present work, the contact between the load and support rollers and the specimen has been modeled with linear gap elements. The type of element and refinement of the mesh have been analyzed in order to minimize numerical error. After having selected those parameters, a complete model with discretization of load and support rollers has been developed to simulate different test conditions. The numerical displacement field has been compared with analytical and experimental results obtained previously. Furthermore, the length and location of the contact between specimen and rollers has been numerically predicted in some configurations.

Keywords

off-axis flexure test finite element method gap elements

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References

<CF f="AdvTimes" n="8.970000"/> Mujika F. , Mondragón I. , Berglund LA and Varna J. 45° flexure test for measurement of in-plane shear modulus. J Compos Mater 2002; 36: 2313-2337.

Mujika F. and Mondragón I. On the displacement field for unidirectional off-axis composites in 3 point flexure. Part I: analytical approach. J Compos Mater 2003; 37: 1041-1066.

Mujika F. , de Benito A. and Mondragón I. On the displacement field for unidirectional off-axis composites in 3 point flexure. Part II: numerical and experimental results. J Compos Mater 2003; 37: 1191-1217.

Chen AT and Yang TY Static and dynamic formulation of a symmetrically laminated beam finite element for a microcomputer. J Compos Mater 1985; 19: 459-475.

Swanson SR Anticlastic effects and the transition from narrow to wide behaviour in orthotropic beams. Compos Struct 2001; 53: 449-455.

Reddy JN A simple higher-order theory for laminated composite plates. J Appl Mech 1984; 51: 745-752.

Oñate E. Cálculo de estructuras por el método de elementos finites. Barcelona: Centro Internacional de Métodos Numéricos en Ingeniería, 1992.

Bosia F. , Gmür T. and Botsis J. Deformation characteristics of composite laminates-part II: an experimental/numerical study on equivalent single layer theories. Compos Sci Technol 2002; 62: 55-66.

Barbero EJ and Reddy JN Modelling of delamination in composite laminates using a layer-wise plate theory. Int J Solid Struct 1991; 28: 373-388.

10.

Robbins DH and Reddy JN Modelling of thick composites using a layerwise laminate theory. Int J Numer Meth Eng 1993; 36: 655-677.

11.

Reddy JN An evaluation of equivalent-single-layer and layer-wise theories of composite laminates. Compos Struct 1993; 25: 21-35.

12.

Auricchio F. and Sacco E. A mixed-enhanced finite-element for the analysis of laminated composite plates. Int J Numer Meth Eng 1999; 44: 1481-1504.

13.

Roufaeil OL and Tran-Cong T. Finite strip elements for laminated composite plates with transverse shear strain discontinuities. Compos Struct 2002; 56: 249-258.

14.

O’Brien TK and Krueger R. Analysis of ninety degree flexure tests for characterization of composite transverse tensile strength. NASA/TM-2001-211227, 2001.

15.

Bosia F. , Facchini M. , Botsis J. , Gmür T. and de’Sena D. Through-the-thickness distribution of strains in laminated composite plates subjected to bending. Compos Sci Technol 2004 ; 64: 71-82.

16.

Cui WC and Wisnom MR Contact finite element analysis of three- and four-point short-beam bending of unidirectional composites. Compos Sci Technol 1992; 45: 323-334.

17.

Belytschko T. , Stolarsky H. and Carpenter N. A triangular plate element with one-point quadrature. Int J Numer Meth Eng 1984; 20: 787-802.

18.

COSMOS/M 1.70 User Guide. Santa Monica, California, USA: Structural Research and Analysis Corporation, 1993.

19.

Theotokoglou EE and Vrettos CD A finite element analysis of angle-ply laminate end-notched flexure specimens. Compos Struct 2006; 73: 370-379.

20.

Mujika F. , Valea A. , Gañán P. and Mondragón I. Off-axis flexure test: a new method for obtaining in-plane shear properties . J Compos Mater 2005; 39: 953-980.

21.

Mujika F. On the difference between flexural moduli obtained by three-point and four-point bending tests. Polym Test 2006; 25: 214-220.