Experimental Study on the Mechanical Property of Loess Mixed with Bentonite-HDTMA

Malan loess in the middle and lower reaches of the Yellow River after mixed with different bentonite and HDTMA ratios was selected to carry out shear and consolidation tests for discussing the influence of bentonite-HDTMA on the mechanical property of loess lining material in landfills. Studies have shown that, after mixing 6% to 14% bentonite, the cohesive force of modified loess is significantly increased, the friction angle is reduced and remains stable, and the shear strength is improved. The compressibility of materials slightly decreases with the increase of bentonite ratio. The addition of 2%–4% HDTMA weakens the increment for the cohesive force caused by bentonite, but the friction angle is effectively recovered. The compressibility of materials increases with the increase of HDTMA ratio. As the dry density increases, the shear strength of the modified loess increases, and the compressibility coefficient decreases. The mechanical property of loess lining material can be optimized by adding 6%–14% bentonite. The incorporation of 2%–4% HDTMA does not have a significant negative impact on the optimization effect of bentonite. From the perspective of the mechanical property, it is recommended that the dry density of modified loess is 1.70 g/cm3, the bentonite ratio is 10%–14%, and the HDTMA ratio is 2%–4%.

Influence of Thermocycling and Sealer Coating Application on Shore Hardness of Soft Denture Lining Material

BACKGROUND: One of the properties of the soft denture lining (SDL) material that needed to overcome the functional problems is softness. Loss of softness due to the aging process and to extend the duration of use, sealer coating was developed to maintain its softness. Sealer coating acts as mechanical barrier to provide protection against aging of SDL materials. AIM: This study aims to determine the influence of thermocycling and sealer coating application on the shore hardness of the acrylic-based and silicone-based auto-polymerizing soft denture lining materials. MATERIALS AND METHODS: Materials that were used in this study are acrylic-based auto-polymerizing SDL (Durabase Soft, Reliance Dental Manufacturing LLC, Illinois, USA) and silicone-based auto-polymerizing SDL (Mollosil, Detax GmbH, Ettlingen, Germany). In this study, we used monopoly as sealer coating for acrylic-based auto-polymerizing SDL and varnish for silicone-based auto-polymerizing SDL. Thermocycling was performed for 2000 cycles for a 2-year simulation time. For shore hardness test, a total of 40 discs shaped samples were made with a diameter of 35 mm and a thickness of 6 mm. The samples were divided into eight groups (n = 5), namely, the uncoated and non-thermocycling acrylic-based auto-polymerizing SDL, the coated and non-thermocycling acrylic-based auto-polymerizing SDL, the uncoated and thermocycling acrylic-based auto-polymerizing SDL, the coated and thermocycling acrylic-based auto-polymerizing SDL, the uncoated and non-thermocycling silicone-based auto-polymerizing SDL, the coated and non-thermocycling silicone-based auto-polymerizing SDL, the uncoated and thermocycling silicone-based auto-polymerizing SDL, and the coated and thermocycling silicone-based auto-polymerizing SDL. The hardness test was carried out using the shore A durometer. RESULTS: The obtained data were tested using the independent t-test with a significance level of p < 0.05. The results showed that there was a significant effect between coated and uncoated acrylic-based SDL group that underwent thermocycling and in the silicone-based SDL group. The study showed that the hardness value was lower in both coated acrylic-based and silicone-based SDL groups compared to the non-coated group, so it can be concluded that the sealer coating is able to protect the hardness of SDL material against aging with a thermocycling simulation. The results also showed that there was a significant effect of thermocycling on the hardness of the material both in the coated acrylic-based SDL group, the uncoated acrylic-based SDL group, and the uncoated silicone-based SDL group. Study also showed that there was no significant effect of thermocycling in the coated silicone-based SDL group. CONCLUSION: Based on the results, it can be concluded that the use of sealer coating can maintain the hardness properties of both acrylic-based SDL and silicon-based self-polymerizing SDL so that it can increase the durability of SDL materials. However, the effect of sealer coating in protecting the hardness of SDL materials against aging was more evident in the silicone-based SDL group.

Mechanical Properties of Novel Reinforced Spray in Place Pipe Material With Potential Fully Structural Performance Application

Many utility owners in the United States are actively searching for new and innovative rehabilitation techniques to help them regain control and repair large tracts of their networks; moreover, traditional open cut replacement is too costly and slow to keep up with demand. Many trenchless techniques such as Spray-In-Place Pipe (SIPP) lining have been adopted by municipalities to renew their aging pipeline systems. The further development of SIPP linings could benefit the water community in the United States and around the world. SIPP lining could play a key role in controlling the future expected burden caused by the aging distribution networks. This study aimed to investigate the mechanical properties of a newly proposed reinforced spray in place pipe (SIPP) lining material that boasts structural characteristics. This material is a spray applied two component polyurethane high build coating. Three forms of sample were investigated during these tests: (1) No Fiber-Baseline (2) Rigid-with one layer of carbon fiber (3) Rigid—with two layers of carbon fiber. Three types of tests are performed: tensile, flexural, and hardness tests. This study included both experimental and Finite Element Analysis (FEA). Target mechanical properties of proposed material can be improved by using carbon fiber (CF) as reinforcement and based on the results of this study, the SIPP lining material with two layers of CF reinforcement has the highest value of 8,067 psi and 16,534 psi during the tensile and flexural test, respectively.

Analysis of rope load sharing on multi-rope friction winders

Ensuring that all the head ropes on a multi-rope friction winder share the load equally has been a design and maintenance issue since they were first developed. Accurate machining of the rope grooves is necessary to meet this objective. Early analysis of the change of rope loads for ropes in grooves that are mismatched in depth treated the grooves as rigid. Groove depth tolerances deduced from this analysis are stringent and difficult to achieve in practice. Test work indicated that the inherent flexibility of groove lining materials alleviates the load-sharing problem. However, no analysis of rope load changes due to mismatched flexible grooves has been published. In this paper we develop new equations for the rope load variation for flexible grooves. By allowing flexibility to reduce to zero, the corresponding rigid rope groove equations are obtained. New criteria for tolerable groove depth variations are developed from this analysis, which depend on the flexibility of the groove lining material.

Effects of grain size on the performance of brake linings with Al2O3 additives

International organizations such as the World Health Organization (WHO) and the International Labor Organization (ILO) have called for an end to the use of asbestos and its derivatives in all sectors, primarily due to the negative effects on human and environmental health. For this reason, manufacturing and use of asbestos linings are also prohibited in most developed countries. For this purpose, there are many studies in the literature on the development and research of nonasbestos linings. In the literature, topics such as material content, production, cost, braking performances and mechanical properties of composite linings are commonly encountered. With the technology in the developing world, the working conditions of vehicle elements are getting more difficult. For this reason, during braking, the amount of energy required to be damped against the unit area in the pad surfaces increases, and since the lining surface areas get smaller, the operating temperatures exceed the limits of the material components. Under these conditions, the design of the lining material content is extremely important, taking into account parameters such as load and operating conditions, in order to slow down or stop the vehicle safely. In this study, the braking performance, mechanical and tribological properties of the samples obtained from a number of production processes such as mixing, pre-shaping and pressing of the materials by altering the particle sizes (50 μm, 75 μm and 125 μm) of the filler and friction materials used together with powdered alumina (Al2O3) were investigated. The most suitable parameters were determined as lining material for the samples obtained.

AWARENESS REGARDING USE OF LINING UNDER POSTERIOR COMPOSITE RESTORATIONS AMONG GENERAL DENTISTS OF LAHORE

Objective: To evaluate awareness among the General Dentists of Lahore regarding the use of lining materials under posterior resin restorations. Study Design: Cross-sectional study. Place and Duration of Study: The study was conducted in Lahore, from Sep 2019 to Jan 2020. Methodology: Non-probability consecutive sampling technique was used. A sample size of 271 was calculated. The questionnaires were distributed by 2 surveyors to the general dentists of Lahore, Pakistan. Results: The response rate was 100%. Amongst these dentists, 191 (63.87%) affirmed that they use lining materials in initial depth cavities, 248 (82.94%) used lining material under moderate depth restorations and 285 (95.31%) used lining materials under advanced depth cavities with calcium hydroxide being the most commonly used material. Conclusion: The findings of the present study indicate that general dentists of Lahore are unaware of the contemporary concepts regarding the placement of cavity liners and tend to place liners in initial and moderate depth cavities under posterior resin restorations.

Hot-pressing design of tubular polyester nonwoven lining material for pipeline rehabilitation

In view of the strength loss and dimension shrinkage of polyester nonwoven used for the sewage pipeline in the hot-pressing process, the response surface methodology was proposed to optimize the technological parameters of lining material. Select the temperature, time and pressure to enhance the hot-pressing process of lining material with the response value of the rate of dimensional change and tensile strength. The results showed that the temperature was 180°C, time was 3s, and pressure was 2.8MPa. Under this process, the rate of dimensional change was 4.23%, transverse tensile strength was 7.95MPa, and longitudinal tensile strength was 5.26MPa. It showed that the response surface methodology had practical application value, and provided a theoretical basis for the hot-pressing parameters of lining material with maximum tensile strength and minimum dimensional shrinkage. The paper also tested the adhesive strength, air permeability and water permeability of lining material under the optimal process, founding that the prepared material had excellent adhesive strength, air permeability, water permeability, and could meet the construction requirements of pipeline rehabilitation and the use requirements of conveying medium.

Wear analysis of eco-friendly non-asbestos friction-lining material applied in an automotive drum brake: Experimental and finite-element analysis

Brake friction lining material is the critical element of a braking system, since it provides friction resistance to the rotating drum for controlling automobiles. The present study involves wear analysis of newly developed eco-friendly non-asbestos friction lining material for automotive drum brake applications using experimental study, finite-element analysis, and microstructural investigations. Theoretical interpretation of braking force at different automobile speeds was derived using fundamentals. Specimen drum brake liner with eco-friendly material compositions was produced using an industrial hot compression molding process at one of the manufacturer. The surface wear of the liner was measured using an effective and accurate method. Furthermore, a finite-element analysis model was developed considering actual operating conditions and various components of the drum brake system. The model was elaborated for various result outcomes, including Von-Mises stresses and total deformation of components of the drum brake, and further used to estimate the surface wear of the friction lining material in terms of transverse directional deformation. Finally, microstructural analysis of the friction lining material was carried out using scanning electron microscopy and energy dispersive spectroscopy. From the results, it is seen that the developed friction lining material is wear resistant. The finite-element analysis model can be effectively utilized to study the tribological characteristics of friction lining materials.

Friction lining coefficient of the drive friction pulley

Mine hoisting KOEPPE system or friction hoist winch work with traction pulley, the pulley rim grooves are lined. Lining has to provide a higher friction coefficient between the rope and the traction pulley. The constructors of mine hoisting machines require from the manufacturers a guaranteed appropriate and stabile value of a friction coefficient at different pressures between a rope and a friction lining under different external conditions (drought, moisture, icing, etc.). The paper presents processed measurements performed on the six samples of the friction lining (G1-G6) made of rubber and the sample of the standard used friction lining (K25). The samples (G1-G6) differ in the chemical composition of the rubber. Due to the confidentiality of the material composition of the friction linings the hardness of the lining material as a discriminator was chosen. The measured values of the friction coefficient of the rubber friction lining samples were compared with the values of the friction coefficient of the friction lining (K25) usually mounted on friction lining pulley.