A 3D Anisotropic Thermomechanical Model for Thermally Induced Woven-Fabric-Reinforced Shape Memory Polymer Composites.

Soft robotic grippers offer great advantages over traditional rigid grippers with respect to grabbing objects with irregular or fragile shapes. Shape memory polymer composites are widely used as actuators and holding elements in soft robotic grippers owing to their finite strain, high specific strength, and high driving force. In this paper, a general 3D anisotropic thermomechanical model for woven fabric-reinforced shape memory polymer composites (SMPCs) is proposed based on Helmholtz free energy decomposition and the second law of thermodynamics.

An Analytical Solution for Inverse Kinematics of SSRMS-Type Redundant Manipulators.

Compared with non-redundant manipulators, the self-motion of 7-DOF redundant manipulators results in an infinite number of inverse kinematics solutions for a desired end-effector pose. This paper proposes an efficient and accurate analytical solution for inverse kinematics of SSRMS-type redundant manipulators. This solution is applicable to SRS-type manipulators with the same configuration.

Real-time profile measurement method for a large-scale satellite antenna.

To improve the detection capability of satellite-based synthetic aperture radar, a large antenna array with a length scale of 100 meters is urgently needed. However, the structural deformation of the large antenna leads to phase errors, which will significantly reduce the antenna gain; hence, real-time and high-precision profile measurements of the antenna are essential for active compensation of the phase and thus improving the antenna gain. Nevertheless, the conditions of antenna in-orbit measurements are rather severe because of limited installation locations of measurement instruments, large areas, and long distance to be measured, and unstable measurement environments.

Design and Application of a Twisted and Coiled Polymer Driven Artificial Musculoskeletal Actuation Module.

Twisted and coiled polymer (TCP) artificial muscles can exhibit unidirectional actuation similar to skeletal muscles. This paper presents a TCP driven artificial musculoskeletal actuation module that can be used in soft robots. This module can contract in the axis direction, and the contraction displacement and force can be controlled easily.

Effect of stress on the molecular structure and mechanical properties of supercontracted spider dragline silks.

Supercontraction is one of the most interesting properties of spider dragline silks. In this study, changes in the secondary structures of the Nephila edulis spider dragline silk after it was subjected to different supercontraction processes were investigated by integrating synchrotron Fourier transform infrared (S-FTIR) microspectroscopy and mechanical characterization. The results showed that after free supercontraction, the β-sheet lost most of its orientation, while the helix and random coils were almost totally disordered.

Carborane-Containing Aromatic Polyimide Films with Ultrahigh Thermo-Oxidative Stability.

Carborane-containing aromatic polyimide (CPI) films with ultrahigh thermo-oxidative stability at 700 °C have been prepared by casting poly(amic acid) (PAA) resin solution on a glass surface, followed by thermal imidization at elevated temperatures. The PAA solution was prepared by copolymerization of an aromatic dianhydride and an aromatic diamine mixture, including carborane-containing aromatic diamine in an aprotic solvent. The CPI films showed excellent thermo-oxidative stability at 700 °C due to the multilayered protection layers formed on the film surface by thermal conversion of the carborane group into boron oxides.

Emulsion Lyophilization as a Facile Pathway to Fabricate Stretchable Polymer Foams Enabling Multishape Memory Effect and Clip Application.

Solvent freezing is an important method to produce polymer foams with highly tunable pore structure. However, foams prepared from aqueous solution precursors commonly suffer from poor water resistance, whereas those organo-phase systems are not environmental friendly. Here, we present that using an emulsion lyophilization method can overcome such a contradiction and synthesize multifunctional polymer foams.

Precise correlation of macroscopic mechanical properties and microscopic structures of animal silks-using Antheraea pernyi silkworm silk as an example.

Animal silks, as one type of high performance natural material, display a unique combination of modulus, tensile strength, and extensibility that gives rise to a greater toughness than any other natural or synthetic fibers. Many previous researchers have already suggested that such excellent comprehensive mechanical properties should be closely related to their special molecular structures. In this paper, we provide more direct evidence to such an assumption by using Antheraea pernyi silkworm silk (tussah silk) as an example with synchrotron radiation FTIR microspectroscopy as a major characterization tool.

Insights into Silk Formation Process: Correlation of Mechanical Properties and Structural Evolution during Artificial Spinning of Silk Fibers.

The extraordinary comprehensive mechanical properties of animal silk (especially spider and silkworm silk) have led to extensive research on the underlying mechanisms involved. Herein, we selected various regenerated silk fibroin (RSF) fibers by choosing different postdraw conditions in a wet-spinning process developed in this laboratory to study their structure-property relationship. We use synchrotron radiation infrared and X-ray diffraction techniques to monitor the structural differences in these RSF fibers and correlate them with their mechanical properties.

Dramatic Enhancement of Graphene Oxide/Silk Nanocomposite Membranes: Increasing Toughness, Strength, and Young's modulus via Annealing of Interfacial Structures.

We demonstrate that stronger and more robust nacre-like laminated GO (graphene oxide)/SF (silk fibroin) nanocomposite membranes can be obtained by selectively tailoring the interfacial interactions between "bricks"-GO sheets and "mortar"-silk interlayers via controlled water vapor annealing. This facial annealing process relaxes the secondary structure of silk backbones confined between flexible GO sheets. The increased mobility leads to a significant increase in ultimate strength (by up to 41%), Young's modulus (up to 75%) and toughness (up to 45%).

Exploration of the tight structural-mechanical relationship in mulberry and non-mulberry silkworm silks.

The Bombyx mori silkworm is well known as it has been bred by our ancestors with mulberry tree leaves for thousands of years. However, Bombyx mori is not the only silkworm that can produce silk, many other kinds of silkworms can also make silks for commercial use. In this research, we compare the mechanical properties of five different commercial silk fibres including domesticated mulberry Bombyx mori, non-mulberry semi-domesticated eri Samia ricini, and wild tropical tasar Antheraea mylitta and muga Antheraea assamensis.

Formation of different gold nanostructures by silk nanofibrils.

Metal nanostructures that have unique size- and shape-dependent electronic, optical and chemical properties gain more and more attention in modern science and technology. In this article, we show the possibility that we are able to obtain different gold nanostructures simply with the help of silk nanofibrils. We demonstrate that only by varying the pH of the reaction solution, we get gold nanoparticles, nano-icosahedrons, nanocubes, and even microplates.

Tough protein-carbon nanotube hybrid fibers comparable to natural spider silks.

Animal silks, especially spider dragline silks, have an excellent portfolio of mechanical properties, but it is still a challenge to obtain artificial silk fibers with similar properties to the natural ones. In this paper, we show how to extrude tough regenerated silk fibers by adding a small amount of commercially available functionalized multiwalled carbon nanotubes (less than 1%) through an environmentally friendly wet-spinning process reported by this laboratory previously. Most of the resulting regenerated silk fibers exhibited a breaking energy beyond 130 MJ m, which is comparable to spider dragline silks (∼160 MJ m).