The Effects of Manufacturing Parameters on Static Characteristics of Water Hydraulic Artificial Muscles

Abstract

The static characteristics of water hydraulic artificial muscles (WHAMs) are related to operating parameters and manufacturing parameters. Operating parameters include working pressure and contraction ratio. Manufacturing parameters include initial braiding angle, fiber sleeve material, and initial rubber tube thickness. These manufacturing parameters fundamentally influence the static characteristics of artificial muscle. Orthogonal experiments were designed with an initial braiding angle of 25 degrees and 32 degrees, fiber sleeve of UHMWPE and aramid 1414, and initial rubber tube thickness of 2mm and 3mm to study the significance level of the effects of these factors and their interactions on the static characteristics of WHAMs. Experiments were carried out at different contractions to study the relationship between contraction force and working pressure, and Analysis of Variance (ANOVA) analyzed the test data. The analysis results showed that the significance level of the initial braid angle on WHAM's static characteristics is the most significant; the significance level of fiber sleeve material and initial rubber tube thickness on the static characteristics of WHAMs depends on the working pressure and contractions. The analysis results help people fabricate different WHAM types according to the working conditions, which help people better control the contraction forces. INDEX TERMS Fiber sleeve material, initial braiding angle, rubber tube thickness, water hydraulic artificial muscles. I.INTRODUCTION

Analysis on fatigue behavior of water hydraulic artificial muscles under different elastic loads in underwater environment

“…The structure of high-strength WHAM is shown in Figure 1, which includes a neoprene rubber tube, an aramid fiber sleeve, a hollow end fitting, a closed-end fitting, a pair of small crimping rings, and a pair of large crimping rings. 18 The fatigue of WHAM depends on the flexible parts, namely, the rubber tube and the fiber sleeve. Therefore, the fatigue behavior of rubber and fibers was analyzed and compared as follows.…”

“…The ultimate contraction rate ε is 36% when the WHAM contracts at an unloaded state. 39,40 Therefore, taking contraction rates ε as 10%, 20%, and 30%, the corresponding strain energy densities À W ε are 252, 466, and 707 kJÁm À3 , respectively. Meanwhile, combined with Equations (2.6), (2.9), and (2.10), the fatigue life of rubber tubes in WHAMs is 3.65 Â 10 8 times, 2.49 Â 10 7 times, and 4.08 Â 10 6 times, respectively.…”

“…The ultimate contraction rate ε is 36% when the WHAM contracts at an unloaded state 39,40 . Therefore, taking contraction rates ε as 10%, 20%, and 30%, the corresponding strain energy densities − W ε are 252, 466, and 707 kJ·m −3 , respectively.…”

“…15,16 It has the advantages of high structural flexibility, excellent adaptability, and intelligent bionic actuation. The artificial muscle has made significant progress in structures and materials, 17,18 actuation, 19,20 modeling analysis, 21 and sensor control. 22,23 However, the long-term service capability is also crucial.…”