UNIVERSITY OF THE BASQUE COUNTRY OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 UNIVERSITY OF THE BASQUE COUNTRY DETERMINATION OF TRANSVERSE COMPRESSIVE STRENGTH OF LONG FIBER COMPOSITES BY THREE-POINT BENDING OF [90m/0n] LAMINATED STRIPS N.Carbajal, A. Arrese, G. Vargas, F. Mujika Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
3. OPTIMAL CONFIGURATION 4. EXPERIMENTAL 5. RESULTS AND DISCUSSION OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 OUTLINE 1. INTRODUCTION 2. ANALYTICAL APPROACH 3. OPTIMAL CONFIGURATION 4. EXPERIMENTAL 5. RESULTS AND DISCUSSION 6. CONCLUSSIONS Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
determining transverse compressive strength. OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 1. INTRODUCTION • Three-point bending tests of cross-ply laminate strips are proposed for determining transverse compressive strength. • Stress state has been obtained based on the hypothesis of the Classical Beam Theory (CBT) • An adequate configuration has been obtained by imposing the condition of maximum ratio between compressive stresses at 90º layer and tensile stresses at 0º layers. • Three-point bending tests with different thicknesses and spans have been carried out. Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
2. ANALYTICAL APPROACH MAIN HIPOTHESES OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 2. ANALYTICAL APPROACH MAIN HIPOTHESES • Longitudinal strain on x axis ex is a linear function of z, where the reference of z coordinate is at the midplane. • The only non vanishing stress components in each ply are sx and ts. • Each ply is linearly elastic. Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
STRESS-STRAIN RELATIONS AT A LAYER FORCES AND MOMENTS PER UNIT LENGTH OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 STRESS-STRAIN RELATIONS AT A LAYER FORCES AND MOMENTS PER UNIT LENGTH Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
STRAINS AND CURVATURES OF MIDPLANE OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 STRAINS AND CURVATURES OF MIDPLANE Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
OPTIMAL THICKNESS RATIO OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 STRESS RATIO OPTIMAL THICKNESS RATIO MAXIMUM STRESS RATIO Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
STRESS RATIO, THICKNESS RATIO AND MODULUS RATIO OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 STRESS RATIO, THICKNESS RATIO AND MODULUS RATIO Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
3. OPTIMAL CONFIGURATION CONDITIONS IMPOSED FOR OPTIMAL CONFIGURATION OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 3. OPTIMAL CONFIGURATION CONDITIONS IMPOSED FOR OPTIMAL CONFIGURATION • Neutral axis has to be located as close as possible to the bottom part of 90º layer in order to avoid tensile stresses at 90º layer. • Maximum thermal stresses must be lower than transverse strength in order to avoid premature failures in 90º layer. • Maximum tensile stresses at 0º layer must be lower than tensile strength. Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
OPTIMAL CONFIGURATION FOR T6T-F593 -> [904n/0n] OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 OPTIMAL CONFIGURATION FOR T6T-F593 -> [904n/0n] Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
MAXIMUM TRANSVERSE COMPRESSIVE STRESS OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 MAXIMUM TRANSVERSE COMPRESSIVE STRESS TRANSVERSE COMPRESSIVE STRENGTH FOR T6T-F593 Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
4. EXPERIMENTAL THREE-POINT BENDING T6T-F593 CARBON/EPOXY SAMPLES OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 4. EXPERIMENTAL THREE-POINT BENDING MTS electromechanical machine Roller radius = 2.5 mm T6T-F593 CARBON/EPOXY SAMPLES Sample h (mm) hT (mm) hL (mm) [909/03]-30 [9016/04]-30 [9020/05]-40 2.07 2.97 3.90 1.55 2.38 3.12 0.52 0.59 0.78 Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
5. RESULTS AND DISCUSSION OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 5. RESULTS AND DISCUSSION STRESS PROFILES [909/03]- 30 Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 STRESS PROFILES [9016/04]- 30 Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 STRESS PROFILES [9020/05]- 40 Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 PHOTOS OF FAILURE Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
LOAD UNLOAD CYCLES PRIOR TO FAILURE OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 LOAD UNLOAD CYCLES PRIOR TO FAILURE Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
strength by three-point bending only depends on the relation OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 6. CONCLUSIONS • Optimal cross-ply configuration for determining transverse compressive strength by three-point bending only depends on the relation between transverse and longitudinal modulus. • For optimal configuration of a given material the ratio between maximum stresses at 90º and 0º layers are maximum and only depends on the relation between transverse and longitudinal modulus. • Transverse compressive strength values are very similar between them. • The appearance of damage agrees well with the transverse compressive failure related to end-loaded compression tests. • No tensile failure has been found prior to final failure. Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips
THANK YOU FOR YOUR ATTENTION OFF-AXIS FLEXURE 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 THANK YOU FOR YOUR ATTENTION Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips