Antimicrobial Activity and Degradation Ability Study on Nanoparticle-Enriched Formulations Specially Designed for the Neutralization of Real and Simulated Biological and Chemical Warfare Agents

The present work reveals a comprehensive decontamination study on real and simulated biological and chemical warfare agents (BCWA). The emphasis was on evaluating the antimicrobial activity against real biological warfare agents, such as Bacillus anthracis, and also the capacity of neutralizing real chemical warfare agents, such as mustard gas or soman, by employing three different types of organic solutions enriched with ZnO, TiO2, and zeolite nanoparticles, specially designed for decontamination applications. The capacity of decontaminating BCWA was evaluated through specific investigation tools, including surface monitoring with the swabs method, minimum inhibitory (MIC) and minimum bactericidal concentration (MBC) evaluations, time-kill tests for microorganisms, and GC-MS for monitoring chemical agents on different types of surfaces (glass, painted metal, rubber, and cotton butyl rubber). These tests revealed high decontamination factors for BCWA even after only 10 min, accomplishing the requirements imposed by NATO standards. At the completion of the decontamination process, the formulations reached 100% efficacy for Bacillus anthracis after 10–15 min, for soman after 20–30 min, and for mustard gas in an interval comprised between 5 and 24 h depending on the type of surface analyzed.

Study on dynamic mechanical properties of O-ring with large ring diameter ratio based on metal rubber

The demand for High temperature resistant metal rubber seals (MRS) with large ring-to-diameter ratio is very urgent in the industrial field. In this work, an O-type MRS with a large ring-to-diameter ratio was developed by embedding the spiral network metal rubber into the stainless steel ring with a special preparation process. The effects of frequency, porosity, and amplitude on the dynamic experimental performance of O-type MRS were studied in detail. The mechanical properties of the MRS were characterized by dynamic tests, and the damping sensitivity were analyzed by orthogonal tests. The results show that MRS has better stability under different frequencies of vibration. The energy consumption and loss factor of the sample increase with increases of porosity. With an increase in loading amplitude, the energy consumption and loss factor of the same porosity test sample increases, whereas the dynamic average stiffness of the specimen gradually decreases. Furthermore, the range analysis of the orthogonal experiment shows that the factors affecting the damping performance of the seal are porosity>amplitude>frequency. This study fills in the dynamic mechanical properties of O-shaped MRS, and provides a certain foundation for the engineering application of O-shaped MRS.

Investigation of Mechanical Behavior of Layered Metal-Rubber Composites Based on Steel and Aluminum Alloy

Metal-polymer composites are advanced materials for the aerospace, automotive and railway industry where details and elements of construction are affected by impact, cyclic and vibration loads. In the present work layered composites based on steel, aluminum alloy and rubber as intermediate layers were obtained by cold and hot bonding using adhesives. Adhesive lap-shear bond strength of layered composites fabricated by various techniques was determined using tensile shear test. To evaluate the mechanical behavior of layered metal-rubber composites under simulated operational conditions static, dynamic and cyclic, three points bending tests were carried out. The results of mechanical tests of these composites indicated that hot bonding is the most preferred fabrication method for the formation of increased mechanical characteristics.

English Estimating Fatigue of Nr45 Natural Rubber Used in Crank Pulley

Rubber is used as a vibration damper in many engineering applications, especially in the automotive industry. Rubber is used to dampen torsional vibration in internal combustion engines. Therefore, crank pulleys are used to dampen the crankshaft in a certain frequency range. Rubber durability is very important for the crank pulley to perform its duty for a long time. In this study, the dynamic life of NR45 natural rubber with two different mixtures used in crank pulleys was determined by the prepared test approach. A metal-rubber component structure used in the slip test samples was formed and produced. The metal-rubber component is left to force the rubber in the vertical direction with its natural frequency and specified amplitude to simulate torsional vibration in crank pulleys. A test setup design was carried out to force the metal-rubber component at the determined frequency. In the study, life expectancy estimates based on amplitude and frequency were created on experimental data.

Performance degradation of metal rubber seal under high temperature and pressure

Seals are crucial components of mechanical devices; seal degradation limits the performance of mechanical systems and even causes accidents. In this work, we used a complex sealing test system to conduct long-term leakage experiments of metal rubber seals as a function of temperature and pressure. The leakage rate was the performance degradation indicator. We developed an experimental performance degradation pattern by linear regression. We combined the leakage pattern of metal rubber seals with leakage theory and found that the increase in the equivalent leakage channel height is the immediate reason for metal rubber seal performance degradation, itself fundamentally attributable to the time-dependent plasticity caused by material creep.

Predicting Nonlinear and Anisotropic Mechanics of Metal Rubber Using a Combination of Constitutive Modeling, Machine Learning, and Finite Element Analysis

Metal rubber (MR) is an entangled fibrous functional material, and its mechanical properties are crucial for its applications; however, numerical constitutive models of MR for prediction and calculation are currently undeveloped. In this work, we provide a numerical constitutive model to express the mechanics of MR materials and develop an efficient finite elements method (FEM) to calculate the performance of MR components. We analyze the nonlinearity and anisotropy characteristics of MR during the deformation process. The elasticity matrix is adopted to express the nonlinearity and anisotropy of MR. An artificial neural network (ANN) model is built, trained, and tested to output the current elastic moduli for the elasticity matrix. Then, we combine the constitutive ANN model with the finite element method simulation to calculate the mechanics of the MR component. Finally, we perform a series of static and shock experiments and finite element simulations of an MR isolator. The results demonstrate the feasibility and accuracy of the numerical constitutive MR model. This work provides an efficient and convenient method for the design and analysis of MR components.