Piercing soft solids: A mechanical theory for needle insertion

How friction and adhesion affect the mechanics of deep penetration in soft solids

“…“Gel” 11 indicates a self-assembled triblock copolymer gel with “ ψ = 0.12, 0.16, 0.20, 0.30” indicating the volumetric fractions of polymer (12, 16, 20, and 30%). For this material, the authors reported μ , G c , R , and the P-vs.-d plot that we used to extract P ′ but did not report α 18 estimated α = 9 from needle insertion studies on the same experiments. Here, we estimated ξ = 0.02 − 0.06, while no estimation of τ a / μξ is needed given the small influence of adhesion in this high toughness regime.…”

“…17 This then provides the correlation between the needle-specimen configuration, a / R , and the mechanical behavior of the material as described by G c / μR and α . 17,18…”

“…At β = β 0 , the contact pressure is zero ( p = 0) and we define β 0 as the angle of needle-specimen contact. Because a / R is uniquely defined by G c / μR and α , 17,18 we calculate 〈 p 〉 and β 0 numerically, via FEA, as a function of G c / μR and α . The pressure distribution reported in this figure considers a > R , since a < R gives nearly uniform pressure distribution and β 0 = π/2.…”

“…7 A mechanical description of puncture and deep penetration, in relation to material properties, has been provided via experimentation [8][9][10][11][12][13][14][15][16] and theory. 17,18 Experimental observations evidenced the role of friction and adhesion in mediating needle penetration. 15,19,20,[22][23][24] Friction is important in both deep penetration and needle extraction, as observed in medical operations like suture, 21 and in nature.…”

Rational mechanochemical design of Diels–Alder crosslinked biocompatible hydrogels with enhanced properties

“…36 Note that while the puncture force is representative of a material strength, a positive relationship between this quantity and fracture toughness has been previously observed in experiment 38 and modeling. 39 Further, recent work has suggested a link between bond strength and puncture force. 16 As presented in Fig.…”