Preliminary discussion on the ignition mechanism of exploding foil initiators igniting boron potassium nitrate

Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics.An oscilloscope,a photon Doppler velocimetry,and a plasma spectrum measurement system were employed to obtain information of electric characteristics,impact pressure,and plasma temperature.The results of the electric characteristics and the impact pressure were inconsistent with ignition results.The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration(HTD).It eventually concludes that the ignition mechanism in this research is the microconvection heat transfer rather than the shock initiation,which differs from that of exploding foil initiators detonating explosives.Furthermore,the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper.The HTD is the critical parameter for judging the ignition success,and it is influenced by two factors:the late time discharge and the energy of the electric explosion.The longer time of the late time discharge and the more energy of the electric explosion,the easier it is to expand the HTD,which improves the probability of the ignition success.

Bearing capacity of circular footings on multi-layered sand-waste tire shreds reinforced with geogrids

The presence of waste tires poses an environmental challenge as they occupy a significant amount of land and are expensive to dispose in landfills.However,reusing waste tires can address this issue when waste tires are used in geotechnical applications.To determine the viability of this approach,laboratoryscale tests were conducted to investigate load-bearing capacity of circular footings on sand-tire shred(STS)mixtures with shredded waste tire contents of 5%e15%by weight and three different widths of shreds.The investigation focused on analyzing the thickness of layers composed of STS mixtures,the soil cap,and the impact of geogrids on bearing capacity.The results indicate that a specific mixture of sand and tire shreds provides the highest footing-bearing capacity.In addition,the optimal shred content and size were found to be 10%by weight and 2 cm×10 cm,respectively.Furthermore,for a given tire shred width,a particular length provides the largest bearing capacity.The results agree well with that of previous research conducted by the first author and his colleagues in direct shear and California bearing ratio(CBR)tests.The primary finding of this research is that the use of two-layered STS mixtures reinforced by geogrids significantly enhances the bearing capacity.

Enhancing Fire Safety in Commercial Vehicles: Assessing the Efficacy and Advantages of Exploding Fire Extinguishing Balls

Fire incidents in commercial vehicles pose significant risks to passengers, drivers, and cargo. Traditional fire extinguishing systems, while effective, may have limitations in terms of response time, coverage, and human intervention [1]. This study investigates the efficacy of a novel fire suppression technology—the Exploding Fire Extinguishing Ball (EFEB) —as an alternative and complementary fire safety solution for commercial vehicles. The research employs a multidisciplinary approach, encompassing engineering, materials science, fire safety, and human factors analysis. A systematic literature review establishes a comprehensive understanding of existing fire suppression technologies, including EFEBs. Subsequently, this study analyzes the unique features of EFEBs, such as automatic activation, as well as manual activation upon exposure to fire, and their potential to provide rapid, localized, and autonomous fire suppression. The study presents original experimental investigations to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. Experiments include controlled fires in confined spaces and dynamic simulations to emulate real-world fire incidents. Data on activation times, extinguishing capability, and coverage area are collected and analyzed to compare the efficacy of EFEBs with traditional fire extinguishing methods. Furthermore, this research shows the practical aspects of implementing EFEBs in commercial vehicles. A feasibility study examines the integration challenges, cost-benefit analysis, and potential regulatory implications. The study also addresses the impact of EFEBs on vehicle weight, stability, and overall safety. Human factors and user acceptance are crucial elements in adopting new safety technologies. Therefore, this research utilizes an experimental design to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. This dissertation presents original controlled experiments to emulate real-world fire incidents, including controlled fires in confined spaces and dynamic simulations. The experimental approach ensures rigorous evaluation and objective insights into EFEBs’ potential as an autonomous fire suppression system for commercial vehicles. This includes the perspectives of drivers, passengers, fleet operators, insurance agencies, and regulatory bodies. Factors influencing trust, perceived safety, and willingness to adopt EFEBs are analyzed to provide insights into the successful integration of this technology. The findings of this research will contribute to the knowledge of fire safety technology and expand the understanding of the applicability of EFEBs in commercial vehicles.

Mechanical properties and damage evolution characteristics of waste tire steel fiber-modified cemented paste backfill

During the process of constructional backfill mining,the cemented paste backfill(CPB)typically exhibits a high degree of brittleness and limited resistance to failure.In this study,the mechanical and damage evolution characteristics of waste tire steel fiber(WTSF)-modified CPB were studied through uniaxial compression tests,acoustic emission(AE)tests,and scanning electron microscopy(SEM).The results showed that the uniaxial compressive strength(UCS)decreased when the WTSF content was 0.5%,1%,and 1.5%.When the WTSF content reached 1%,the UCS of the modified CPB exhibited a minimal decrease(0.37 MPa)compared to that without WTSF.When the WTSF content was 0.5%,1%,and 1.5%,peak strain of the WTSF-modified CPB increased by 18%,31.33%,and 81.33%,while the elastic modulus decreased by 21.31%,26.21%,and 45.42%,respectively.The addition of WTSF enhances the activity of AE events in the modified CPB,resulting in a slower progression of the entire failure process.After the failure,the modified CPB retained a certain level of load-bearing capacity.Generally,the failure of the CPB was dominated by tensile cracks.After the addition of WTSF,a gradual increase in the proportion of tensile cracks was observed upon loading the modified CPB sample to the pore compaction stage.The three-dimensional localization of AE events showed that the WTSF-modified CPB underwent progressive damage during the loading,and the samples still showed good integrity after failure.Additionally,the response relationship between energy evolution and damage development of WTSF-modified CPB during uniaxial compression was analyzed,and the damage constitutive model of CPB samples with different WTSF contents was constructed.This study provides a theoretical basis for the enhancement of CPB modified by adding WTSF,serving as a valuable reference for the design of CPB constructional backfill.

Development and Validation of a Scaled Electric Combat Vehicle Tire Model

Pneumatic tire modeling and validation have been the topic of several research papers, however, most of these papers only deal with pneumatic passenger and truck tires. In recent years, wheeled-scaled vehicles have gained lots of attention as a feasible testing platform, nonetheless up to the authors’ knowledge there has been no research regarding the use of scaled tires and their effect on the overall vehicle performance characteristics. This paper presents a novel scaled electric combat vehicle tire model and validation technique. The pro-line lockdown tire size 3.00 × 7.35 is modeled using the Finite Element Analysis (FEA) technique and several materials including layered membrane, beam elements, and Mooney-Rivlin for rubber. The tire-rim assembly is then described, and the rigid body analysis is presented. The tire is then validated using an in-house custom-made static tire testing machine. The tire test rig is made specifically to test the pro-line tire model and is designed and manufactured in the laboratory. The tire is validated using vertical stiffness and footprint tests in the static domain at different operating conditions including several vertical loads. Then the tire is used to perform rolling resistance and steering analysis including the rolling resistance coefficient and the cornering stiffness. The analysis is performed at different operating conditions including longitudinal speeds of 5, 10, and 15 km/h. This tire model will be further used to determine the tractive and braking performance of the tire. Furthermore, the tire test rig will also be modified to perform cornering stiffness tests.

Predictive modelling of volumetric and Marshall properties of asphalt mixtures modified with waste tire-derived char:A statistical neural network approach

The goals of this study are to assess the viability of waste tire-derived char(WTDC)as a sustainable,low-cost fine aggregate surrogate material for asphalt mixtures and to develop the statistically coupled neural network(SCNN)model for predicting volumetric and Marshall properties of asphalt mixtures modified with WTDC.The study is based on experimental data acquired from laboratory volumetric and Marshall properties testing on WTDCmodified asphalt mixtures(WTDC-MAM).The input variables comprised waste tire char content and asphalt binder content.The output variables comprised mixture unit weight,total voids,voids filled with asphalt,Marshall stability,and flow.Statistical coupled neural networks were utilized to predict the volumetric and Marshall properties of asphalt mixtures.For predictive modeling,the SCNN model is employed,incorporating a three-layer neural network and preprocessing techniques to enhance accuracy and reliability.The optimal network architecture,using the collected dataset,was a 2:6:5 structure,and the neural network was trained with 60%of the data,whereas the other 20%was used for cross-validation and testing respectively.The network employed a hyperbolic tangent(tanh)activation function and a feed-forward backpropagation.According to the results,the network model could accurately predict the volumetric and Marshall properties.The predicted accuracy of SCNN was found to be as high value>98%and low prediction errors for both volumetric and Marshall properties.This study demonstrates WTDC's potential as a low-cost,sustainable aggregate replacement.The SCNN-based predictive model proves its efficiency and versatility and promotes sustainable practices.

Study of the Evolution of Properties of Concrete Containing Used Tire Aggregates

Concrete is generally composed of cement, water, gravel, and sand. However, some research focuses on substituting aggregates with waste materials. In this study, used tires are used as a substitute for gravel. Characteristics such as tensile strength, compressive strength, and porosity were monitored at 7, 14, and 28 days of maturation. The results show that aggregates made from used tires are suitable for concrete production and can replace natural gravel. Regarding the formed concrete, low substitution rates lead to improved concrete properties, but only at an early age. A reaction between the cement and rubber could be the underlying cause. Additionally, the products of this reaction may mitigate the evolution of the compressive strength of the concrete over time.

Finite Element Simulation of Radial Tire Building and Shaping Processes Using an Elasto-Viscoplastic Model

The comprehensive tire building and shaping processes are investigated through the finite element method(FEM)in this article.The mechanical properties of the uncured rubber from different tire components are investigated through cyclic loading-unloading experiments under different strain rates.Based on the experiments,an elastoviscoplastic constitutive model is adopted to describe themechanical behaviors of the uncured rubber.The distinct mechanical properties,including the stress level,hysteresis and residual strain,of the uncured rubber can all be well characterized.The whole tire building process(including component winding,rubber bladder inflation,component stitching and carcass band folding-back)and the shaping process are simulated using this constitutive model.The simulated green tire profile is in good agreement with the actual profile obtained through 3D scanning.The deformation and stress of the rubber components and the cord reinforcements during production can be obtained fromthe FE simulation,which is helpful for judging the rationality of the tire construction design.Finally,the influence of the parameter“drum width”is investigated,and the simulated result is found to be consistent with the experimental observations,which verifies the effectiveness of the simulation.The established simulation strategy provides some guiding significance for the improvement of tire design parameters and the elimination of tire production defects.

Non-Pneumatic Tire Design and Modeling: An Overview of Research

The research provides valuable insights into the intricate world of Non-Pneumatic (NP) tire technology, covering various facets from modeling and validation to material properties, design optimization, and tire-soil interactions. It begins with an exploration of existing NP tire modeling techniques, emphasizing the importance of accurate and reliable models for NP tires, including static and dynamic validation methods, and demonstrating the influence of structural features and material properties on tire performance. The review emphasizes the challenges and prospects of NP tires and aims to support the development of innovative airless tire solutions. The reviewed papers collectively contribute to a deeper understanding of NP tires, their applications, and potential enhancements in performance and efficiency across various industries.

Workability and Durability of Concrete Incorporating Waste Tire Rubber:A Review

Environmental problems caused by waste tires are becoming increasingly prominent.There is an urgent need to find a green way to dispose of waste tires,and scholars have made considerable efforts in this regard.In the construction industry,rubber extracted from waste tires can be added to concrete to alleviate environmental problems to a certain extent.As a new building material,rubber concrete has superior properties compared to ordinary concrete and has been widely used in many fields.Numerous studies have been conducted worldwide to investigate the effect of waste tire rubber on the performance of concrete.It has been reported that the addition of waste tire rubber has a significant influence on the performance of concrete.Workability influences the hardened performance of rubber concrete,especially the durability.Based on the current research results,the workability and durability of concrete manufactured with waste tire rubber,including water absorption and permeability,carbonation resistance,chloride ion permeability resistance,and freeze-thaw resistance,are summarized in this paper.It is concluded that the addition of waste tires has a negative effect on the workability of concrete.In terms of durability,concrete exhibits better chloride ion penetration resistance and frost resistance,with a higher water absorption rate,and lower anti-permeability and carbonation resistance owing to the addition of waste tire rubber.

Determination of the Sound Absorption Capacity of Hydraulic Concrete Mixtures Added with Waste Tire Rubber

There are different types of pollutants that are harmful to the environment, including smog, chemicals that are dumped into rivers, scrap tires, etc. The latter have the particularity that it is not possible to recycle them to manufacture new tires. In the present work, hydraulic concrete plates added with waste tire rubber were manufactured to modify their sound absorption capacity. It was found that the rubber additions produce changes in the density of the material and in the sound absorption capacity. When the material is exposed to high-frequency sounds that correspond to high-pitched sounds, its absorption capacity increases. On the contrary, when the test frequency is low, that is, bass sounds, the sound absorption capacity decreases. The results obtained in this work suggest that the proposed mixtures are suitable for the possible manufacture of acoustic insulating shields.

汽车轮胎滚动阻力研究综述

汽车轮胎稳态滚动阻力作为轮胎力学特性之一,对汽车的动力性、燃油经济性、制动性、操纵稳定性以及轮胎使用寿命等具有重要影响。阐述了轮胎滚动阻力产生机理,总结了轮胎滚动阻力的试验测量、数值仿真和理论计算方法;分析了车轮结构参数及材料属性对轮胎滚动阻力的影响;指出了汽车轮胎滚动阻力研究的技术挑战及发展趋势,可为轮胎滚动阻力的研究提供一定的参考。

Waste Recovery and Sustainable Development. A Case Study of Material Development from Used Tires in Africa

This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for the manufacture of O-rings has been developed, with properties close to those found on the market. The process includes an experimental methodology of a sulfur vulcanization system choice and the quantification of ingredients, as well as the experimental determination of cure parameters. Mechanical tests on the samples completed the work by providing the mechanical characteristics of both unaged and aged (thermo-oxidative ageing) novel material. This process has a high potential for sustainable development and industrialization, making it a valuable contribution to the recycling of rubber in African developing countries.

某直列式点火器双路瞎火故障分析与改进

针对某直列式点火器在低温点火试验中出现的双路冲击片点火管瞎火问题,进行了故障定位及原因分析,提出了改进措施并对其有效性进行了试验验证。结果表明:造成双路瞎火故障的原因是点火器转接件焊点异常处的气体间隙弧光放电;提出将2个回路的触发信号时间间隔调整为50μs,按照HB 7262航空产品电装工艺的相关规定细化电装工艺,增加对能量传输通道的介质耐压检测等改进措施。验证试验表明采取改进措施后,消除了弧光放电现象,点火器内的2个爆炸箔表面均有明显的电爆炸痕迹。

超声波脱硫再生胶对NR/SSBR/BR胎面胶性能的影响

将具有较高脱硫程度的超声波脱硫轮胎胶粉再生胶(DGTR)加入到天然橡胶/溶聚丁苯橡胶/高顺式顺丁橡胶(NR/SSBR/BR)胎面胶料中,研究了DGTR用量对胎面橡胶复合材料流变性能、硫化特性和力学性能的影响。流变性能测试结果表明,随着DGTR用量的增加,在较低频率下复合材料的黏度和储能模量增加,损耗因子降低,说明DGTR能改善填料在橡胶基体中的分散,降低胎面胶滚动阻力。硫化特性和力学性能结果表明,DGTR的加入能缩短胎面胶料的硫化时间,并提高其撕裂强度和300%定伸应力;当其用量不超过20份时,对胎面胶料拉伸强度影响较小。

用于轮胎振动分析的壳模型优化研究

虽然现有壳模型在0~500 Hz频带内精度高,适合用于轮胎结构振动分析,但由于模型中耦合了胎侧二维壳模型,导致胎冠振动模态难以分离,且模型自由度和所需输入参数增加。本文对该壳模型进行改进:在保持胎冠壳模型不变的基础上,应用轮胎环模型和板模型中对胎侧的近似方法,采用弹性基底代替胎侧二维壳模型,简化了原模型的边界条件并缩减了输入参数个数;针对改进后的壳模型建立了求解方法,实现了胎冠模态频率和振型的求解。并通过与实验数据的对比,验证了改进后的壳模型及其求解方法的正确性。

基于流固耦合的轮胎花纹滑水性能研究

以205/55 R16型号轮胎为研究对象,基于Abaqus CEL流固耦合方法构建轮胎滑水有限元模型。将模拟得到的轮胎垂直刚度与实验数据进行对比,验证轮胎模型可靠性的前提下,优化欧拉域,更好地捕捉并分析轮胎滑水时水流印迹特征。结合NASA经验公式评估模拟得到的临界滑水速度,验证轮胎滑水模型可靠性,分析不同充气压力和水膜厚度对轮胎临界滑水速度的影响。通过引入V型横向花纹和增加F1 Nose结构优化轮胎花纹结构,验证花纹沟槽子模型优化合理性,对比优化前、后轮胎临界滑水速度和水流压力。结果表明:此优化方法能有效提高轮胎的滑水性能。

应用新结构、新材料开发配套低滚动阻力轮胎

应用新结构、新材料开发配套12R22.5 C600低滚动阻力轮胎。应用超高强度骨架材料,胎体采用0.17+5×0.215+10×0.235CCST钢丝帘线,带束层采用4+3×0.35ST钢丝帘线,钢丝包布采用0.17+5×0.215+10×0.235CCST钢丝帘线;优化配方设计,胎面胶采用低滚动阻力胶料,基部胶采用低滞后损失胶料;优化胎冠弧设计以及胎肩和胎圈部位材料分布。成品轮胎的充气外缘尺寸符合国家标准要求,耐久性能良好,滚动阻力达到欧盟标签C级,满足客户的需求,轮胎装车后行驶里程达到20万km,与普通轮胎相比,平均每百公里可节油1.13 L。

非充气轮胎的滚动越障振动仿真分析

采用仿真分析方法探究非充气轮胎的滚动越障振动特性。建立非充气轮胎的有限元模型,对辐条式原始非充气轮胎(简称原始轮胎)和轮辐仿生优化非充气轮胎(简称优化轮胎)的滚动越障振动进行仿真分析,研究滚动速度和障碍物高度对原始轮胎和优化轮胎的径向和纵向振动的影响,以及两种轮胎的振动特性与其滚动越障时接地压力峰值标准差之间的关系。结果表明:越障时滚动速度和障碍物高度的增大会加剧非充气轮胎的径向和纵向振动;与原始轮胎相比,优化轮胎的减振效果主要体现在滚动速度和障碍物高度变化时其振动特性较为平稳;接地压力峰值标准差能够在一定程度上表征非充气轮胎的振动强度。非充气轮胎的滚动越障振动仿真分析为其动态特性研究奠定了一定的理论基础,对提高车辆的稳定性具有重要的意义。

矿用重载轮胎趾口空问题的研究

通过市场返回轮胎断面剖析,结合有限元仿真分析造成矿用重载轮胎趾口空的原因,并提出相应的解决措施。通过采取适当减小胎圈内直径,适当增大胎圈与轮辋过盈量、三角胶尺寸、胎体反包高度,提高耐磨胶的硬度和耐老化性能,在推荐充气压力和负荷范围内使用轮胎及在车辆上安装液压减速器以降低刹车片使用频次等措施,可降低趾口空发生率,延长轮胎使用寿命。