Dynamic Mechanical Properties of Polyvinyl Alcohol Hydrogels Measured by Double-Striker Electromagnetic Driving SHPB System

Abstract

As an ultra-soft material (elastic modulus in magnitude of kPa), polyvinyl alcohol (PVA) hydrogels have the potential to substitute articular cartilage, but the measurement of the dynamic stress–strain relations of ultra-soft materials is still challenging. In this paper, a double-striker electromagnetic driving split-Hopkinson pressure bar (SHPB) system was developed, in which all the bars were made of polycarbonate, and the polycarbonate striker was pushed by a metal striker driven electromagnetically to ensure the precise control of impact velocity. With the new SHPB system, well design of the size of hydrogel specimen and rational processing of the signal data, the stress–strain relations of hydrogels with varied PVA contents at different strain rates were measured successfully. Experimental results indicate that PVA hydrogels are a positive strain rate sensitive material with different strain-rate effects at low and high strain rates. Finally, based on the latest quasi-static constitution of the PVA hydrogel, a rate-dependent constitutive equation was recommended, which may well depict the mechanical behaviors of hydrogels with different fiber contents at varied strain rates. It also derives that the contributions of strain rate and fiber content on the mechanical behaviors of the hydrogel are relatively independent.

Strong Interfaces Enable Efficient Load Transfer for Strong, Tough, and Impact-Resistant Hydrogel Composites

“…Investigating the impact responses of hydrogels promises broad applications, ranging from predicting the penetration pressure of skin by a hypodermic needle for injection administration, , to the assessment of tissue damage caused by incidents, , or chronic disease like the progression of osteoarthritis under consecutive impacts . Albeit the impact responses of biological tissues have been intensively evaluated, − the examinations of the behaviors of synthetic hydrogels subjected to impact are relatively scarce. − More importantly, the synthetic hydrogels impacted so far are mostly fragile that the hydrogel may shatter into fragments after impact, which is adverse for postanalysis. Because many applications of synthetic hydrogels, such as tissue-mimicking phantoms and protective fabrics, are readily encountered impact loads, synthesizing hydrogels that are strong and tough under not only quasi-static but also impact loads and probing their impact responses are of great practical importance yet remain elusive.…”

Swelling response of functionally graded temperature-sensitive hydrogel valves: Analytic solution and finite element method

“…Behavior of the hydrogel materials was also observed when they were probed in binary solvents to investigate the cosolvency and cononsolvency effects (Xiao et al, 2019). Moreover, the dynamic properties and phase transition of temperature-sensitive hydrogels are subjects that have attracted researchers, recently (Shoujing and Zishun, 2018;Xie et al, 2019). Besides the super absorption of these materials, the high flexibility and recoverability of hydrogel deformation drew researchers to use these materials in wide applications, for example, smart sensors and actuators (Beebe et al, 2000;Ionov, 2013), micro-valve (Beebe et al, 2000;Jadhav et al, 2015;Liu et al, 2002;Wang et al, 2005), tissue engineering (Wong et al, 2008), and drug delivery (Baghani et al, 2019;Graham and McNeill, 1984;Liu et al, 2006;Peeridogaheh et al, 2019).…”