Improved accuracy in the determination of flexural rigidity of textile fabrics by the Peirce cantilever test (ASTM D1388)

Abstract

Within the field of composite manufacturing simulations, it is well known that the bending behavior of fabrics and prepregs has a significant influence on the drapeability and final geometry of a composite part. Due to sliding between reinforcements within a fabric, the bending properties cannot be determined from in-plane properties and a separate test is required. The Peirce cantilever test represents a popular way of determining the flexural rigidity for these materials, and is the preferred method in the ASTM D1388 standard. This work illustrates the severe inaccuracies (up to 72% error) in the current ASTM D1388 standard as well as the original formulation by Peirce, caused by ignoring higher-order effects. A modified approach accounting for higher-order effects and yielding significantly improved accuracy is presented. The method is validated using finite element simulations and experimental testing. Since no independent tests other than the ASTM D1388 standard are available to determine the bending stiffness of fabric materials, experimental validation is performed on an isotropic, homogeneous Upilex-50S foil for which the flexural rigidity and tensile stiffness are related. The flexural rigidity and elastic modulus are determined through both the cantilever test (ASTM D1388) and tensile testing. The results show that the proposed method measures an elastic modulus close to that determined through tensile testing (within 1%), while both the Peirce formulation (+18%) and ASTM standard (+72%) over-estimate the elastic modulus. The proposed methodology allows for a more accurate determination of flexural rigidity, and enables the more accurate simulation of composite forming processes

Finite element prediction of resin pocket geometry around embedded optical fiber sensors in prepreg composites

“…Note that because of the large displacements, standard beam theory is no longer valid for these experiments. Modified formulations need to be used in order to determine the bending stiffness from these results [21]. Using the differential equation approach to the Peirce cantilever test presented in [21] it is possible to simulate the bending behavior of a composite ply for different values of bending stiffness.…”

“…Modified formulations need to be used in order to determine the bending stiffness from these results [21]. Using the differential equation approach to the Peirce cantilever test presented in [21] it is possible to simulate the bending behavior of a composite ply for different values of bending stiffness. Using a least-squares fit between the theoretical and experimental displacements (Table 2), the bending stiffness of the ply is determined.…”

Research on the relationship between the age of blood stains and the bending rigidity of blooded cotton fabric

“…Peirce's cantilever test methodology is preferred to determine the bending stiffness in fabric materials and a fixed angle 41.5° is used for a inclined surface [6].The FAST-2 bending tester, which is based on the principle of cantilever test method, was used to test the bending properties of fabric. Under the standard atmosphere enviroment, the FAST-2 bending tester can directly measure the bending length of fabric and then the bending rigidity is calculated from the Equation (1) [6,7].…”

“…Under the standard atmosphere enviroment, the FAST-2 bending tester can directly measure the bending length of fabric and then the bending rigidity is calculated from the Equation (1) [6,7]. The principle of the cantilever test method is showed in Figure 2.…”

FE Tool for Drape Modelling and Resin Pocket Prediction of Fully Embedded Optical Fiber Sensor system

“…The vertical displacement of the sample after curing is recorded in order to extract the bending response of the ply. Note that as large deformations are involved, beam theory can no longer be used and a more advanced formulation as presented in [8] should be used.…”