Smart Table Tennis Racket with Tunable Stiffness for Diverse Play Styles and Unconventional Technique Training

Abstract: Smart technologies bring innovation to the life and sports arena. To adapt to diverse play styles and improve unconventional technique of table tennis players, a smart table tennis racket with tunable stiffness based on anisotropic electrorheological elastomers (EREs) is developed. The EREs are prepared in the designed mold under the electric field to form an anisotropic structure that consisted of electrorheological particles and facilitated the generation of interparticle saturation surface polarization and the local electric field. Therefore, the electrorheological property of anisotropic EREs is significantly promoted, attaining a relative electrorheological effect of 17,160% in shear mode, and the incremental shear storage and compression modulus of 5.2 and 6.4 MPa. By applying an electric field, the smart racket successfully changes the trajectory of balls, reduced ejection angle by 11% and increased ejection velocity by 2%.

适用于不同打球风格和非常规技术训练的智能乒乓球拍

摘要：智能技术为生活和运动领域带来创新。为了适应乒乓球运动员不同的打法，提高其非常规技术水平，研制了一种基于各向异性电流变弹性体（EREs）的刚度可调的智能乒乓球拍。在定制的模具中，在电场下制备了ERE，形成由电流变颗粒组成的各向异性结构，有利于颗粒间饱和表面极化和局域场的产生。因此，各向异性ERE的电流变特性得到显著提升，在剪切模式下获得17160%的相对电流变效应，剪切储能模量增量和压缩模量增量分别为5.2和6.4 MPa。通过施加电场，智能球拍成功改变了球的轨迹，出射角减小了11%，出射速度提高了2%。

论文链接：https://onlinelibrary.wiley.com/doi/10.1002/admt.202100535

原文分享：(PDF) Smart Table Tennis Racket with Tunable Stiffness for Diverse Play Styles and Unconventional Technique Training (researchgate.net)

Figure 1. Schematic illustrations of EREs from preparation to application, in which E denotes the electric field and F0 denotes constant shear force. Anisotropic EREs are prepared by the mold a). The conception of the smart table tennis racket based on EREs b). Working principle of EREs c). In presence of E, the deformation of EREs is less than that in absence of E. The application of the smart racket d), in which the trajectory of the ball varies  with the electric field.

Figure 2. The electrorheological effect of EREs in shear and compression mode. The shear storage modulus increment ΔG′ and the relative ER effect of S0, S1, S2, and S3 at 3 kV mm−1 compared to 0 kV mm−1 a). The elastic modulus E in compression mode of S0, S1, S2, and S3 at different strain under 0 and 1.5 kV b). The way applied force in shear and compression mode damages particle chain segments c), E for the electric field.

Figure 3. Characterization and tests of EREs. The optical microscope images a) of the precursor (left) of EREs without the electric field and the EREs (right) cured under 0.5 kV mm−1 . The cross-section SEM images of a segment of particle chain in anisotropic EREs at low concentration b). The dielectric spectrum of EREs c) (solid symbols denotes dielectric constant and open symbols denotes dielectric loss). Time dependence of electrorheological effect d) of the anisotropic EREs. The cycle tests in shear mode e) and compression mode f).

Figure 4. Application of the smart table tennis racket. The schematic illustrations of the smart table tennis racket and sectional view a). The reverse side of the racket b) and the racket face c).

Figure 5. The hitting effect tests of the ERE unit. The trajectory of the ball in the vertically hitting test a). The rebound height and ejection velocity of the ball as a function of the electric field in the vertically hitting test b). The trajectory of the ball in the askew hitting test c). The incidence angles and the ejection angles of the ball in the askew hitting test under 0 and 1.5 kV mm−1 d). The incidence velocities and the ejection velocities of the ball in the askew hitting test under 0 and 1.5 kV mm−1 e).