Songquan Wang

Research on the Interstitial Fluid Load Support Characteristics and Start-Up Friction Mechanisms of PVA-HA-Silk Composite Hydrogel

Hydrogel has been extensively studied as an articular cartilage repair and replacement material. PVA-HA-Silk composite hydrogel was prepared by freezing-thawing method in this paper. Mechanical properties were determined by experiments and the friction coefficient of PVA-HA-Silk composite hydrogel against steel ball was verified using micro-tribometer. Finite Element Method (FEM) was used to study the lubrication mechanism of PVA-HA-Silk composite hydrogel and the relation between the interstitial fluid load support and the start-up friction resistance. The results show that the elastic modulus and the permeability are 2.07 MPa and 10−15m4N−1s−1, respectively, and the start-up friction coefficients of PVA-HA-Silk composite hydrogel are in the range of 0.15–0.2 at different contact loads, contact time and sliding speeds. The start-up friction resistance of PVA-HA-Silk composite hydrogel increases with the contact load and contact time. With the increase in sliding speed, the start-up friction resistance of PVA-HA-Silk composite hydrogel decreases. There is an inverse relation between the start-up friction resistance and the interstitial fluid load support. The change of fluid flow with the increase in sliding displacement has an important effect on the interstitial fluid load support and friction resistance. The interstitial fluid load support decreases with the increase in contact load and contact time, while the interstitial fluid load support reinforces with the increase in sliding speed. Moreover, PVA-HA-Silk composite hydrogel has mechanical properties of recovery and self-lubricating.

Interactive mechanisms of fretting wear and corrosion of steel wires in alkaline corrosion medium

Fretting corrosion tests of steel wires inside a rope were performed on a self-made fretting wear test rig to understand the fretting corrosion behaviors of steel wires under the environment of alkaline mine water trickling using a simulated alkaline corrosion medium. The results indicate that the corrosion rate of steel wire decreases rapidly and then increases with the increase in the duration of immersion. For late immersion, the corrosion rate tends to be smooth because of the large accumulation of corrosion products. It is also found that the evolution of friction coefficient vs fretting cycles can be divided into five stages. With the increase in the fretting cycles, there is an increase in the weight loss of materials and the evolution processes of damage rate can also be divided into four stages. All the results conclude that interaction of corrosion and wear dominates the fretting corrosion and leads to material loss.

A fretting fatigue tester for steel wires and its measuring system

A self-made fretting fatigue tester for steel wire based on the computer-controlled electro-hydraulic servo fatigue testing machine is introduced in the paper. The working principle and experimental method are described. The signals of contact load, fretting tangential force and fretting amplitude are collected using force and displacement sensors. Synchronous acquisition and dynamic display of the signals of various parameters are realized using the dynamic signal analyzer. The friction coefficient curve is obtained by processing the signals of various parameters using MATLAB software as well as the change curve of fretting tangential force with the fretting amplitude in different fretting cycles. The tester for steel wires is applied to study the mechanism of fretting fatigue, fretting fatigue life and fretting running regime characteristics.