A Dynamic Modeling Method for the Bi-Directional Pneumatic Actuator Using Dynamic Equilibrium Equation

Dynamic modeling of soft pneumatic actuators are a challenging research field. In this paper, a dynamic modeling method used for a bi-directionaly soft pneumatic actuator with symmetrical chambers is proposed. In this dynamic model, the effect of uninflated rubber block on bending deformation is considered. The errors resulting from the proposed dynamic equilibrium equation are analyzed, and a compensation method for the dynamic equilibrium equation is proposed. The equation can be solved quickly after simplification. The results show that the proposed dynamic model can describe the motion process of the bi-directional pneumatic actuator effectively.

Experimental assessment for the thermal performance of scrap tire blocks as external wall insulators

In this paper, the advantage of reusing scrap tires in Scrap Rubber Block (SRB) to improve thermal insulation in buildings was examined experimentally. By testing the use of SRB in black and white colours as external wall insulators and comparing their performance with walls without insulation. The results indicated that a wall with scrap tire blocks gave the best thermal insulation results when the outer face was painted white. The decrement factor (f) and the rate of heat loss increase, while the rate of heat gain decreases. This was done through the mechanisms of heat transfer by conduction through the layers of the wall and the effect of adding the rubber block on its thermal properties. The results showed that the use of rubber blocks reduces the temperature of the inner surface of the wall by 3-4oC lower than the traditional wall. The thermal diffusion inside the wall was determined effectively in the case of a wall with the rubber block, where the temperature of the inner surface reaches its maximum value by about 0.5-hour difference from the traditional wall in the case of the wall with the rubber block in black colour, and 9.5-hour in the case with the white block.

Validation and optimization of a compact push-pull rubber actuator energized by an outer coil of shape memory wire

The authors have formerly published the analytical model and finite element validation of a push-pull actuator made by winding a thin shape memory wire on a solid rubber cylinder. The cylinder provides elastic backup for the wire upon cooling down and transforms its circumferential contraction into a magnified axial elongation upon heating up. Building on that study, this paper accomplishes three tasks: (1) build prototype actuators and perform simple tests to validate the theory; (2) develop simple procedures for the optimal design of the actuator starting from high-level engineering specifications; (3) envision how the present concept could be improved by replacing the rubber block with a compliant lattice-like or shell-like scaffold with designed properties to further enhance the axial stroke.

The effects of grooved rubber blocks on stick–slip and wear behaviours

This work presents an experimental and theoretical combined study of the effects of the elastic rubber blocks with different surface modifications on the friction-induced stick–slip oscillation and wear of a brake pad sample in sliding contact with an automobile brake disc. The experiments are conducted on the customized experimental setup in a pad-on-disc configuration. The experimental results show that (1) the friction system with the plain rubber block still exhibits visible stick–slip oscillation, but the intensity of the stick–slip oscillation is reduced to a certain degree compared with the Original friction system (without rubber block); (2) the grooved rubber blocks display a better ability to reduce the stick–slip oscillation compared with the plain rubber block; (3) the rubber blocks with a vertical groove (perpendicular to the relative velocity) or a horizontal groove (parallel to the relative velocity) or a diagonal groove (45° inclined to the relative velocity) on their surfaces can suppress the stick–slip oscillation more effectively with various degrees of success. The experimental results also reveal the varying effects of the different rubber blocks on wear. To explain the experimental phenomenon reasonably, a theoretical analysis is conducted to investigate the effects of different rubber blocks on both stick–slip oscillation and wear using ABAQUS. Furthermore, the analysis of the contact pressure on the pad interfaces and the deformation of the rubber blocks are studied to provide a possible explanation of the experimental results.

Investigation of Snow Milling Mechanics to Optimize Winter Tire Traction

ABSTRACT A detailed understanding of effects occurring in the contact patch between tire tread and snow surface is needed to maximize tire grip in winter conditions. The main focus of this study is quantifying the snow milling effects of individual tire tread block elements during sliding. Tests are carried out using the high-speed linear friction tester (HiLiTe), located at the Institute of Dynamics and Vibration Research at Leibniz University of Hannover, Germany. Test tracks are prepared using artificially produced snow. To solely investigate snow milling effects and exclude material properties of rubber, in a first instance the tread block samples are made of polytetrafluoroethylene (PTFE). Because PTFE is at the same time rigid and hydrophobic, known friction mechanisms such as adhesion and hysteresis can be neglected, leaving only the tread pattern milling mechanics to transmit frictional forces to the snow track. The PTFE samples are shaped in such a way that they mimic the geometry of different siped rubber tread blocks under load, varying the sipes' number, shape, and tilt angle. Results show the benefit of multiple sipes and give information on the evolution of transmittable forces with respect to sliding distance. It is found that the block element shape and tilt angle are directly linked to the frictional force, showing a distinct optimum for specific angle and shape combinations. In addition, forces are not depending on sliding speed, but on sliding distance. The snow milling results of PTFE block elements are then compared to siped rubber block samples. Corresponding high-speed videos show that PTFE sample snow milling mechanics can be directly applied to rubber samples.

Carbon footprint inventory of rubber industry in two phases planting and processing in Binh Duong province

With the objective of assessing the current greenhouse gas emissions and proposing solutions to reduce greenhouse gas emissions from planting and processing of rubber industry in Binh Duong province, the study using the Life Cycle Assessment (LCA) method combined with instructions of IPCC (2006), the study has done the inventory of greenhouse gas emissions in plantation and processing plants in 11 plantations and 03 processing plants of Dau Tieng Rubber Co.Ltd, Binh Duong province. The results showed that emissions in plantation is 1,038.2 kg C/ton product, 91.5% to 94.6% from the total emissions of the products; emissions of rubber blocks from latex is 1,134.7 kg C/ton product; emissions of rubber block from latex condensed is 1,098.0 kg C/ton product; emissions of latex concentrated is 1,110.8 kg C/ton product; emissions of skim block is 1,123.9 kg C/ton product. In addition, the study also proposes measures to reduce greenhouse gas emissions in plantation and processing plant. The measures is mainl focused on changing the way of using fertilizers, increased efficiency of using urea in rubber trees and reduce the amount of fertilizer containing urea /nitrogen. Study results will help managers and enterprises control greenhouse gas emissions from rubber latex processing industry in Binh Duong province.