Influence of friction on out-of-plane properties in the curved beam angle test ASTM-D6415 for hydrofoil marine application.
Topic(s) : Experimental techniques
Co-authors :
Cyran LE GUENNEC (FRANCE)Abstract :
Appendix architectures of IMOCA and ULTIM Hydrofoils enter into mechanical challenge soliciting highly out of plane properties. Foil extremities are spread in case of hydrodynamic lift load inversion, stirring out-of-plane stress in its curved angle. This solicitation in out-of-plane direction for high thick composite structure clearly lead the mechanical foil sizing of the laminate as much as compression and interlaminar shear strengths.
Engineering sizing approach of composite aerostructure suggested in out of plane analyses for composite structure (PAUL, 1990) characterizing out plane properties in five load cases associated to composite structure typologies. This involves : load path eccentricity, ply drop off, direct/undirect out-of- plane loading and geometric discontinuity.
The first approach had characterized out of plane on pad loading out-of-plane direct tensile test. While representing complementary use case load, this test on pad presenting high concentration stresses around the bounding linking the test equipment to the coupons, often generating excepted coupons. In the aim to characterize out-of-plane in another way, rigidity (E33) and stress (S33), IRDL centre research and ComposiTIC Technical platform studies have carrying out four points bending on curved beam angle following ASTM D6415 standard method (MAKEEV, 2015) representing eccentricity load path.
Researches led by M. Grabow, (Grabow, 2022), have defined the influence of manufacturing processes on the S33 and E33 properties. Composite angle coupons are carried out by innovating hydrofoil repeatable and reliable automated fibre placement (AFP) manufacturing. Those researches linked composite aerostructure manufacturing to marine manufacturing. New batch studies has started by studying the influence out-of-plane tensile strengths on carbon fibres thermoset matrix composite (C/TS) and thermoplastic composites (C/TP) to identify the potential mechanical values and capabilities (AUCHER, 2009) of C/TP for Hydrofoils use case.
The four points bending test improvement has guided the study by first analysing what is the friction influence on ASTM D6415 device, and, how is impacting out-of-plane properties. A non-negligible influence of friction has been observed and quantified. Friction sources come from the various contacts of the bench itself and between the bench and curved beam angle. Impact on the E33 and S33 results were highlighted in a special test campaign using three four-point angles bending test configurations: bearings guided by bearing connections, bearings guided by needle bearing connections and, finally, polycarbonate pads between each bearing and the composite and C/TD angle.
Engineering sizing approach of composite aerostructure suggested in out of plane analyses for composite structure (PAUL, 1990) characterizing out plane properties in five load cases associated to composite structure typologies. This involves : load path eccentricity, ply drop off, direct/undirect out-of- plane loading and geometric discontinuity.
The first approach had characterized out of plane on pad loading out-of-plane direct tensile test. While representing complementary use case load, this test on pad presenting high concentration stresses around the bounding linking the test equipment to the coupons, often generating excepted coupons. In the aim to characterize out-of-plane in another way, rigidity (E33) and stress (S33), IRDL centre research and ComposiTIC Technical platform studies have carrying out four points bending on curved beam angle following ASTM D6415 standard method (MAKEEV, 2015) representing eccentricity load path.
Researches led by M. Grabow, (Grabow, 2022), have defined the influence of manufacturing processes on the S33 and E33 properties. Composite angle coupons are carried out by innovating hydrofoil repeatable and reliable automated fibre placement (AFP) manufacturing. Those researches linked composite aerostructure manufacturing to marine manufacturing. New batch studies has started by studying the influence out-of-plane tensile strengths on carbon fibres thermoset matrix composite (C/TS) and thermoplastic composites (C/TP) to identify the potential mechanical values and capabilities (AUCHER, 2009) of C/TP for Hydrofoils use case.
The four points bending test improvement has guided the study by first analysing what is the friction influence on ASTM D6415 device, and, how is impacting out-of-plane properties. A non-negligible influence of friction has been observed and quantified. Friction sources come from the various contacts of the bench itself and between the bench and curved beam angle. Impact on the E33 and S33 results were highlighted in a special test campaign using three four-point angles bending test configurations: bearings guided by bearing connections, bearings guided by needle bearing connections and, finally, polycarbonate pads between each bearing and the composite and C/TD angle.