Analytical and experimental investigation of puncture-cut resistance of soft membranes

Abstract

Modeling and evaluating critical puncture-cutting force and total applied energy are among the most important steps in characterizing the resistance of protective materials to sharp-tipped object insertion. This paper explores the relationship between these two mechanical properties, force and energy, corresponding to the insertion of a pointed blade into soft membranes. The paper's main contribution includes the addition of friction energy to the existing analytical cutting model in order to develop a more comprehensive model. This energy is provided by the normal stress (contact pressure) caused by the created fracture surface. The contact pressure is applied on both lateral sides of the pointed blade. In this work, a model describing the combined puncture and cutting of protective materials is developed using force distribution analysis and basic concepts of fracture mechanics. Results show that the critical puncture-cutting force (F P/C) required for complete insertion of a pointed blade decreases with the increase of the puncture-cut ratio, ζ, given by the shape of the pointed blade. In other words, the puncture cutting of soft membranes is easier when the pointed blade has a high cutting edge angle than when it has a small cutting edge angle. Fracture mechanics theory is then used to determine the relationship between F P/C and the total puncture-cutting energy, G Total , that includes fracture toughness of material and friction energy. The presented model is verified by comparing the predicted values of F P/C with experimental data obtained from puncture-cutting tests of soft elastomeric materials and soft-coated fabrics by three pointed blades. According to the proposed model, the methods corresponding to force measurement (F P/C) or energy calculation (G Total) are both able to evaluate accurately the puncture-cut resistance of protective materials by any sharp-tipped objects.

Combined Puncture and Cutting of Soft-Coated Fabrics by a Pointed Blade: Energy, Force and Stress Failure Criteria

“…As mentioned in section ''Puncture-cutting mechanisms of soft elastomer-coated fabrics,'' it is assumed that the contribution of the fabric structure during pointed-blade insertion (before the blade tip reaches the underside of the membrane) is negligible due to the blade's acute tip. Therefore, G C can be estimated to be about 40% of G Total , as in the case of soft elastomeric materials, reported by Triki et al [17,18]. The same values of the fitting parameters (c I = 0.055, c II = 0.55 and c III = 0.8) estimated for puncture cutting of soft elastomeric membranes were then used for soft elastomer-coated fabrics.…”

“…In this section, total puncture-cutting energy, G Total , was calculated using a procedure outlined in our previous articles [17,18]. According to this procedure, G Total is given by…”

“…In this section, we examine the two analytical models of critical puncture-cutting force, which were developed for soft elastomeric membranes and based on energetic analysis (equation ( 9)) [17] and stress analysis (equation ( 8)) [24]. In equations ( 8) and ( 9), F P/C depends not only on total energy (Figure 6), Poisson's ratio (Table 3), and Young's modulus (Table 2) but also on fracture energy (fracture toughness), G C , and the three fitting parameters.…”

Finite Element Modelling for Predicting the Puncture Responses in Papayas

“…Figure 5 a–d shows the typical pattern of deformations and stress waves of the FE model of the sample after the simulated puncture with a rigid needle-like probe under the prescribed insertion velocity. The von Mises criterion was used to estimate the total contact stress, which was regarded as the sum of shear and principal stress components throughout [ 27 ]. In general, the simulation model was able to discriminate the differences in the apparent puncture stress being experienced by the samples at the different puncture times.…”

Combined puncture and cutting of elastomer membranes: A fracture energy approach

“…The first fundamental study of puncture and cutting by pointed blades was done by Triki, who developed an alternative approach to calculating the true fracture energy corresponding to the puncture and cutting of neoprene rubber by pointed blades based on Rivlin and Thomas's and Lake and Yeoh's theories. However, this alternative approach is complicated and involves a lot of experimental tests.…”