CHARACTERIZING DUAL MATRIX COMPOSITE ORIGAMI DEPLOYMENT

Lightweight strain-energy deployable structures are well suited for applications in spacecraft structures and deployable habitats. Dual matrix composite origami describes a composite structure that utilizes two uniquely different matrix systems in the same fiber structure. An epoxy matrix is used to form rigid sections and a silicone matrix creates bending regions where one can create a collapsible structure. The added elastic properties of the silicone matrix allow the composite to harness internal strain-energy to spring open from a folded configuration to a flat plane. This is advantageous for solar arrays as they can be folded for compact transit and then return to a flat surface after being deployed. In this work, initial ground testing is used to verify repeatable deployment prior to micro gravity flight testing. To characterize the motion of the composite structures as they deploy, OptiTrack Flex 13 cameras are used in sync with a deployment mechanism that repeatably releases and tracks the origami structures. The data collected in this study will be used to validate the use of the flight rig, deployment mechanism, and motion tracking system for future micro gravity flight testing. Once tested and characterized in a micro gravity setting, the dual matrix composite origami structures developed in this work can be applied to large solar arrays to power next generation spacecraft and satellites with lower complexity compared to other deployable technology.

Determination of Mechanical and Tribological Properties of Silicone-Based Composites Filled with Manganese Waste

High-tonnage industrial processes generate high amount of waste. This is a growing problem in the whole world. Neutralizing such waste can be time consuming and costly. One of the possibilities of their reuse is to use them as fillers in polymer composites. Introduction of the filler in polymer matrix causes change in its mechanical and tribological properties. In the article, the effect of introducing fillers from post-production waste, and its effect on changing the physical properties of silicone-based composites filled with manganese (II) oxide and waste manganese residue was investigated. The composites were made by gravity casting. Composites with 2.5, 5, 7.5, and 10 wt% of the fillers were examined. The composite materials were subjected to tests such as: density, hardness, resilience, tensile test, abrasion resistance, and ball-on-disc. Microscopic images showed that, the particles of the fillers are uniformly distributed in silicone matrix with the formation of smaller agglomerates. Such agglomerates introduced a discontinuity in the structure of the polymer material, which caused a decrease in the tensile strength and elongation at break for all tested compositions in comparison with the mechanical properties of the silicone used as the matrix. However, it was found that all silicone-based composites filled with manganese (II) oxide and manganese residue showed a reduction in abrasive wear, compared to the reference sample.

Optical-Tactile Sensor for Lump Detection Using Pneumatic Control

Soft tactile sensors are an attractive solution when robotic systems must interact with delicate objects in unstructured and obscured environments, such as most medical robotics applications. The soft nature of such a system increases both comfort and safety, while the addition of simultaneous soft active actuation provides additional features and can also improve the sensing range. This paper presents the development of a compact soft tactile sensor which is able to measure the profile of objects and, through an integrated pneumatic system, actuate and change the effective stiffness of its tactile contact surface. We report experimental results which demonstrate the sensor’s ability to detect lumps on the surface of objects or embedded within a silicone matrix. These results show the potential of this approach as a versatile method of tactile sensing with potential application in medical diagnosis.

EXPERIMENTAL STUDY OF EXOTERMIC EFFECTS INSIDE DENTAL PULP CHAMBER WHEN APPLYING DIRECT TECHNIQUE OF MANUFACTURING TEMPORARY CROWN

The aim of this study is to determine the optimal combination of self-curing resins and type of matrix that provides a minimal temperature increase in the pulp chamber during the fabrication of temporary crowns. Material and methods. We designed as experimental model of direct temporary crown fabrication for extracted and than prepared molars. Intrapulpal temperature rise was measured in vitro conditions during polymerization of Protemp II (3M), Protemp 4 (3M), Visalis Temp (Kettenbach), Structur (Voco) and Carbodent (Stoma). Output and peak temperature findings of self-curing resin polymerization were recorded and values ​​of temperature increase in the tooth chamber were calculated. Two types of materials were used to make external anatomical moulds: 1) silicone impression material Panasil Putty Soft of high and low viscosity and Panasil initial contact Light (Kettenbach) to make two-phase impression; 2) transparent thermoplastic polymer Erkodur (Erkodent), sheet of 1.0 mm thick, vacuum pressed. Results and Discussion. We obtained the following finding of the temperature rise inside the pulp chamber (polymer pattern / silicone matrix): Protemp IV (2,2˚C / 0,2˚C), VisalisTemp (3˚C / 0.3˚C), Protemp II (3,3˚C / 0,5˚C), Structur (3,4˚С/0,6˚С), Karbodent (6.7˚C / 3.0˚C). Conclusions. Exothermic effects during intra oral fabrication of temporary crowns can be minimized by polymerization of resins in the silicone mould as this material can absorb and dissipate heat.

The Influence of Zinc Waste Filler on the Tribological and Mechanical Properties of Silicone-Based Composites

Silicones are often used for various types of coatings, but due to their poor mechanical properties, they often require modification to meet specific requirements. At the same time, various production processes throughout the world generate different types of waste, the disposal of which is harmful to the environment. One possible solution is to use production waste as a filler. In this paper, the authors investigated how the use of metallurgical production waste products as fillers changed the mechanical properties of silicone composites prepared by casting. Composite samples were characterized using tensile tests, resilience, pin-on-disc, Schopper–Schlobach abrasion, hardness, and density measurements. Based on the obtained results, the authors assessed the effect of each of the fillers used in different weight proportions. The results showed that the silicone composite filled with 5 wt% zinc dust showed the lowest decrease in tensile strength and Young’s modulus, with a simultaneous significant reduction in abrasion compared with the reference sample. This research shows that zinc waste can be successfully introduced into a silicone matrix in cases where it is important to reduce abrasive wear.

Multifunctional Magnetic Nanocomposite Encapsulant for EMI Shielding in Power Electronics

As power densities and switching frequencies dramatically increase, a potential area of advancement for encapsulant technologies is to utilize them to mitigate electromagnetic interference, which directly impacts device efficiency at high switching frequencies; one promising topic involves the creation of magnetic nanoparticle-enhanced encapsulants, with intrinsic sensitivity to electromagnetic fields that could provide additional noise shielding for power electronic devices. A nanocomposite encapsulant was created by directly incorporating magnetic iron oxide nanoparticles into a silicone matrix. The nanoparticles, with an average size of 100 nm, achieved excellent dispersion in the silicone polymer, even at high concentrations, with no additive or surfactants needed to improve stability. Material testing, including thermo mechanical analysis and thermal conductivity measurements were performed to determine if the addition of the nanoparticles altered the thermal or mechanical properties of the base silicone. The nanocomposites at different concentrations observed thermal conductivities of 0.5 W/m-K and coefficient of thermal expansions of 280 ppm/°C, which resembles that of normal silicone; however, the addition of the iron oxide reduced the dielectric breakdown strength of the silicone matrix exponentially with respect to concentration from 20 kV/mm to 3 kV/mm. Further efforts to optimize the dielectric properties of the nanocomposites with respect to the nanoparticle loading is necessary in order to directly apply this technology; however, the results indicate magnetic nanocomposites could be a potential avenue towards mitigating electromagnetic interference in power devices.