Dynamic failure analysis of static seals under pressure fluctuation in an ultrahigh-pressure water piston pump

For ultrahigh-pressure piston pumps, in the reciprocating action of the piston, the fretting between the static face seal and the mating surface occurs with the change of the pressure in the piston chamber. This phenomenon will seriously affect the service life of the seal ring and lead to the failure of the pump. However, the failure of static seals used to seal ultrahigh-pressures is usually studied from the directions of shear, stress, or rubber material. These studies cannot explain the failure phenomenon of the sealing ring found in our experiment. This paper analyzed the failure of the face seal ring in a piston pump with a maximum pressure of 120 MPa. A two-dimensional axisymmetric finite element model was established based on the Mooney-Rivlin constitutive relation of the rubber material, and the fretting conditions of the sealing ring were analyzed. Combined with the wear scars observed by the scanning electron microscope the face seal ring’s dynamic failure mechanism on the ultrahigh-pressure piston pump was determined. A better sealing scheme was proposed and verified by the duration test of the pump, which provided a basis for the design of the sealing of the ultrahigh-pressure fluid with high-frequency fluctuations.

A simulation strategy to determine the mechanical behaviour of cork-rubber composite pads for vibration isolation

The present work aimed to determine the performance of new cork-rubber composites, applying a modelling-based approach. The static and dynamic behaviour under compression of new composite isolation pads was determined using mathematical techniques. Linear regression was used to estimate apparent compression modulus and dynamic stiffness coefficient of compounds samples based on the effect of fillers, cork and other ingredients. Using the results obtained by regression models, finite element analysis (FEA) was applied to determine the behaviour of the same cork-rubber material but considering samples with different dimensions. The majority of the regression models presented R2 values above 90%. Also, a good agreement was found between the results obtained by the presented approach and previous experimental tests. Based on the developed methodology, the compression behaviour of new cork-rubber compounds can be accessed, improving product development stages.

The numerical analysis of partial discharge activities of silicone rubber composites

This paper discussed on the partial discharge phenomenon occurs in insulating materials-based silicone rubber. In general, the partial discharges occur due to the presence of additional substances or void in the material. The methods that are used to study partial discharge are offline monitoring, online monitoring, and numerical analysis. The numerical analysis was performed on this silicone rubber compound with the introduction of three identical void with the radius of 1.15 mm. The simulation results show that the pure silicone rubber material experiences the high impact of partial discharge activities compared to the second material; microvaristor filled with silicone rubber.

Liquid smoke application in latex as an environment-friendly natural coagulant

Liquid smoke has many benefits, especially in the food, fishery, timber, and plantation industries. It is used as a preservative or durability increased and aroma and taste addition in the food and fishery industry. In the wood industry, liquid smoke can resist termite attacks, while in the plantation industry, it functions as a latex coagulant containing antifungal, antibacterial, and antioxidants that can improve rubber product’s quality. Most of the rubber farmers in Bangka Belitung still use alum as a coagulant to coagulate their latex. However, alum coagulant can reduce the quality of the processed rubber material (bokar). The reason farmers use alum is that raw materials are cheap, therefore getting coagulant raw materials at low prices and not pollute the environment with a less moderate aroma/odor caused by non-recommended coagulant materials (alum) are needed. This study aims to apply liquid smoke as a natural coagulant in latex freezing. The research method used a Completely Randomized Design, with liquid smoke concentration replicated three times. Parameters observed were clotting time speed and organoleptic test for odor during 14 days of storage. The results showed that the best concentration of liquid smoke was 15% no odor and a clotting time of 8.23 minutes.

Toothbrush Abrasion of Restorations Fabricated with Flowable Resin Composites with Different Viscosities In Vitro

The purpose of this study was to examine toothbrush-induced abrasion of resin composite restorations fabricated with flowable resin composites of different viscosities in vitro. In this study, six types of flowable resin composites with different flowability (Beautifil Flow F02, F02; Beautifil Flow F10, F10; Beautifil Flow Plus F00, P00; Beautifil Flow Plus F03, P03; Beautifil Flow Plus X F00, X00; and Beautifil Flow Plus X F03, X03) were used. For the toothbrush abrasion test, the standard cavity (4 mm in diameter and 2 mm in depth) formed on the ceramic block was filled with each flowable resin composite (n = 10) and brushed for up to 40,000 strokes in a suspension containing commercial toothpaste under the conditions of 500 g load, 60 strokes/min, and 30 mm stroke distance. After every 10,000 strokes, the brushed surface of the specimen was impressed with a silicone rubber material. The amount of toothbrush-induced abrasion observed on each impression of the specimen was measured using a wide-area 3D measurement device (n = 10). The viscosity was determined using a cone-and-plate rotational measurement system. Because of the effect of different shear rates on viscosity and clinical use, the values 1.0 and 2.0 s−1 were adopted as data (n = 6). In this study, the results of the toothbrush abrasion test demonstrated no significant differences in the amount of toothbrush-induced abrasion among flowable resin composites used (p > 0.05). No significant correlation was reported between toothbrush-induced abrasion and viscosities of flowable resin composites.

The COMPOND COMPOSITION OF AIRLESS TIRE TREAD (AIRLES TYRE)

The tire without air is a tire that has a very extraordinary influence on the units of vehicle users, both public vehicles and tactical vehicles in the military. In addition to being used in the field of duty, this airless tire can be used for other supporting vehicles of army so there are not many obstacles during operations. Therefore, it takes good materials and proper calculations in making this airless tire tread so that in the future there are no obstacles when using it. The research methods used are experimental methods and field studies. The study was conducted repeatedly and the data was taken directly in the field. After mechanical testing of the rubber material is done to find out the physical properties of the strength of the material. Furthermore, the entire printing and assembly process is carried out and tested on the vehicle, for the conclusion of static analysis of rubber sample material that has been done has determined the proper hardness for the material connected with polyurethane, the appropriate hardness for this rubber is 80 KN/mm. The process has been tested from each sample of rubber hardness variations and the results are determined, in addition to rheometer testing or maturation process takes 5 minutes and is given a temperature of 100 °C and is assisted by hydraulic so that air from volcanic rubber is lost with the help of hydraulic pressure.

Milestone Sistem Perniagaan Karet di Rimbo Bujang Rentang Tahun 1980-2020

Processed rubber material (bokar) is a commodity that has been the mainstay of the Indonesian government. In order to realize the hegemony of production, the government organizes a transmigration program. This is at the same time to overcome the population problem on the island of Java. This qualitative type of research was carried out using the Bogdan and Taylor field approach using time series data. Patton's data analysis process, presented with manageable data. The data interpretation uses ideal types, path dependency and contingency strategies and Neuman's domain analysis. Research in Rimbo Bujang, in the 1980-2020 period, shows that the rubber trading system in the ex-transmigration sites of Jambi Province can be classified into three phases: first, trade between transmigrant farmers and the government. Second, farmers trade with cooperatives and middlemen. Third, farmers trade with middlemen using an auction pattern. Although the transmigration program in Rimbo Bujang was successful, it still left socio-economic problems, triggered by the trade system which tends to ignore Islamic economic principles. Findings in the field indicate that the absence of the state in plantation smallholder commerce contributes to the moral hazard of market participants. The change of plantation varieties from rubber to oil palm in the last decade does not rule out the possibility of repeating the previous cycle of rubber trading patterns.

Optimal design of a commercial rubber isolator based on creep and creep-resistance analyses

Creep is a common important physical phenomenon in rubber material, which induces the instability of geometrical dimension and deteriorates the mechanical performances. The present work develops an optimal design approach of a commercial rubber isolator based on creep analysis. First and foremost, a nonlinear creep constitutive model of rubber material is established, which can capture the hyper-elastic and time-dependent creep behaviors. Complete mechanical and creep tests of rubber materials are conducted, and material parameters are identified according to the experimental data. Then, the parametric finite element model of a rubber isolator is established, with which the time-dependent creep analysis based on the proposed creep constitutive model is conducted. The accuracy of the numerical creep analysis is validated at material level and structural component level. For engineering application, a sensitivity analysis and optimization design for creep-resistance of the rubber isolator is developed by combing finite element simulation and optimization method. The results show that creep-resistance characteristics of the optimal rubber isolator is largely improved, which provides a long-term stable behavior in vibration attenuation. The proposed method may provide an efficient tool for predicting the creep performance and optimal analysis of other commercial rubber-base products.

The Comparison of Fractional Derivative Model and Classical Spring-Dashpot Model in the Identification of Viscoelastic Characteristics of a Rubber Material

In the design of viscoelastic materials used in rubber products, not theoretical approaches but experimental approaches have been usually employed. This is due to the difficulties in mathematical procedures of the dynamic material characteristics such as the dependencies of strain amplitude, frequency and/or environmental temperature in deformation. In mathematical approach there are two kind of analytical models for a complex module of the material, which are a fractional derivative model and a spring-dashpot model. However there are few papers dealing with the study of the identifications of parameters for the experimental modulus actually obtained not only by using the fractional derivative model but also by using the spring-dashpot model and the discussion of the comparisons of the two models. In the present paper, the complex elastic modulus for a rubber material are obtained experimentally for a wide range of excitation frequency, and the modulus-frequency relations are derived analytically by using the two models, respectively. Finally, the applicability of the models are discussed from the numerical results.