Design and feasibility analysis of a novel auto hold system in hydrostatic transmission wheeled vehicle

Auto hold refers to vehicle’s function of automatic braking under shutdown condition and automatic relieving braking force when vehicle starts. This paper presents a concrete structure of the novel auto hold system of hydrostatic transmission wheeled vehicle, and deeply analyses the working mechanism and control method. To validate its feasibility, AMESim software is adopted to establish the simulation model of the auto hold system based on mathematical theories. By using the data of a certain comprehensive operation mode as input, the curve of braking force of the auto hold system is obtained through simulation. It can be known through analysis that the proposed auto hold system can realize rapid response and provides stable braking force under different road conditions. Finally, the feasibility of the proposed auto hold system is validated by comparing the simulation data with actual braking force required and the electronic vehicle parking technology. It turns out that the auto hold system can meet the requirements of all road conditions. Besides, it also can provide a fault tolerance range for real vehicle experiments, and it will not cause adverse impacts due to excessive parking brake force

Simulation of the support-enclosing rock mass interaction for deep mining

Purpose. To develop analytical model for a support-enclosing rock interaction to determine parameters for operational stability of deep mine workings while decreasing metal consumption and increasing efficient use of resources. Methods. Involving various strength degradation functions and variations of physical and mechanical properties of rocks, mathematical modeling is used to consider the ranges of force action of a support on the enclosing rock mass of deep mine workings. Findings. Analytical dependence of a support effect on the rock border displacement as well as on the changes in cross section of the mine working has been obtained. Effective interval of the support force resistance to block limit zones of the rock mass deformations has been substantiated. Innovative approach relying on the priority of the support working capacity as well as its forming characteristics has been proposed. The results of the studies help regulate the use of available supports, and the development of new designs meeting the increased geomechanical requirements of deep mining. Originality. It has been determined for the first time that 150 – 250 kN/m2 interval of a support resistance is the most efficient and achievable; while mining deepening (more than 1000 m), a support resistance achieves 350 – 400 kN/m2. Higher values are not practical. Practical implications. The results of the studies help regulate the use of available supports, and the development of new designs meeting the increased geomechanical requirements of deep mining and to determine the required parameters of both force and deformational characteristics of supports making.Мета. Розробка аналітичної моделі взаємодії кріплення й масиву для визначення параметрів забезпечення експлуатаційної стійкості гірничих виробок на великих глибинах, зниження їх металоємності та підвищення ресурсозбереження. Методика. Математичним моделюванням із залученням різних функцій знеміцнення та варіації фізико-механічних властивостей гірських порід розглянуті діапазони силових впливів кріплення на масив, що містить виробку глибокого закладення. Результати. Встановлено аналітичну залежність впливу кріплення на зміщення породного контуру та зміну площі перерізу виробки. Обґрунтовано ефективний інтервал силового опору кріплення для блокування граничних зон деформацій масиву. Досліджено параметри працездатності кріплення та його утворюючих характеристик – робочого опору та конструктивної піддатливості як роботи, що забезпечує формування системи “кріплення – масив». Наукова новизна. Запропоновано новий науковий підхід, заснований на пріоритетності параметра працездатності кріплення та його утворюючих характеристик. Вперше встановлено, що найбільш ефективним і реально досяжним є інтервал опору кріплення 150 – 250 кН/м2, зі збільшенням глибини ведення гірничих робіт понад 1000 м опір кріплення сягає 350 – 400 кН/м2, а більш – є недоцільним. Практична значимість. Результати досліджень з достатньою для практичного застосування точністю можуть використовуватися для визначення необхідних параметрів силових і деформаційних характеристик кріплень, дозволяють регламентувати практику використання існуючих кріплень та розробку нових конструкцій, що відповідають підвищеним геомеханічним вимогам великих глибин розробки.Цель. Разработка аналитической модели взаимодействия крепи и вмещающего массива для определения параметров обеспечения эксплуатационной устойчивости горных выработок на больших глубинах, снижения их металлоемкости и повышения ресурсосбережения. Методика. Математическим моделированием с привлечением различных функций разупрочнения и вариации физико-механических свойств горных пород рассмотрены диапазоны силовых воздействий крепи на вмещающий массив выработок глубокого заложения. Результаты. Получена аналитическая зависимость влияния крепи на смещение породного контура и изменения площади сечения выработки. Обоснован эффективный интервал силового отпора крепи для блокировки предельных зон деформаций массива. Исследованы параметры работоспособности крепи и образующих его характеристик – рабочего сопротивления и конструктивной податливости как работы, обеспечивающей формирование системы “крепь – массив”. Научная новизна. Предложен новый научный подход, основанный на приоритетности параметра работоспособности крепи и его образующих характеристик. Впервые установлено, что наиболее эффективным и реально достижимым является интервал отпора крепи 150 – 250 кН/м2, с увеличением глубины ведения горных работ более 1000 м отпор крепи может достигать 350 – 400 кН/м2, а более – является нецелесообразным. Практическая значимость. Результаты исследований с достаточной для практического применения могут использоваться для определения необходимых параметров силовых и деформационных характеристик крепей, позволяют регламентировать практику использования существующих крепей и разработку новых конструкций, отвечающих повышенным геомеханическим требованием больших глубин разработки.The authors express particular gratitude to Hennadii Hor, Doctor of Physical and Mathematical Sciences, Professor, Senior Researcher of Donetsk Institute of Applied Mathematics and Mechanics for his help while carrying out the research and processing the results of the mathematical model

A bibliography /with abstracts/ on gas-lubricated bearings Interim report

Gas lubricated bearings - annotated bibliograph

Volume 1 – Symposium

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group A: Materials Group B: System design & integration Group C: Novel system solutions Group D: Additive manufacturing Group E: Components Group F: Intelligent control Group G: Fluids Group H | K: Pumps Group I | L: Mobile applications Group J: Fundamental

Plasma sprayed titanium coatings with/without a shroud

Abstract: Titanium coatings were deposited by plasma spraying with and without a shroud. The titanium coatings were then assessed by scanning electron microscopy. A comparison in microstructure between titanium coatings with and without the shroud was carried out. The results showed that the shroud played an important role in protecting the titanium particles from oxidation. The presence of the shroud led to a reduction in coating porosity. The reduction in air entrainment with t he shroud resulted in better heating of the particles, and an enhanced microstructure with lower porosity in the shrouded titanium coatings were observed compared to the air plasma sprayed counterpart

Development Of A Semi-Swath Craft For Malaysian Waters

Small Waterplane Area Twin Hull (SWATH) and Catamaran vessels are known to have more stable platform as compared to mono-hulls. A further advantage of SWATH as compared to Catamaran is its smaller waterplane area that provides better seakeeping qualities. However, the significant drawback of the SWATH vessel is when encountering head-sea at high forward speed. Due to its low stiffness, it has a tendency for large pitch motions. Consequently, this may lead to excessive trim or even deck wetness. This phenomenon will not only degrade the comfortability but also results in structural damage with greater safety risks. In this research a modified SWATH design is proposed. The proposed design concept represents a combination of Catamaran and SWATH vessel hull features that will lead to reduce in bow-diving but still maintains good seakeeping capabilities. This is then called the Semi- SWATH vessel. In addition, the full-design of this vessel has been equipped by fixed fore fins and controllable aft fins attached on each lower hull. In the development of controllable aft fins, the PID controller system was applied to obtain an optimal vessel’s ride performance at speeds of 15 (medium) and 20 (high) knots. In this research work, the seakeeping performance of Semi-SWATH vessel was evaluated using time-domain simulation approach. The effect of fin stabilizer on the bare hull performance is considered. The validity of numerical evaluation was then compared with model experiments carried out in the Towing Tank at Marine Technology Laboratory, UTM. It is shown that the Semi-SWATH vessel with controllable fin stabilizer can have significantly reduction by about 42.57% of heave motion and 48.80% of pitch motion

Physiologic responses to water immersion in man: A compendium of research

A total of 221 reports published through December 1973 in the area of physiologic responses to water immersion in man were summarized. The author's abstract or summary was used whenever possible. Otherwise, a detailed annotation was provided under the subheadings: (1) purpose, (2) procedures and methods, (3) results, and (4) conclusions. The annotations are in alphabetical order by first author; author and subject indexes are included. Additional references are provided in the selected bibliography

Predicting lubrication performance between the slipper and swashplate in axial piston hydraulic machines

Engineering of the sliding interfaces within swashplate type axial piston machines represents the most complex and difficult part of the design process. The sliding interfaces are subject to significant normal loads which must be supported while simultaneously preventing component wear to ensure long lasting operation. Proper lubrication design is essential to separate the solid bodies from each other, but the complexity of the physics involved makes this a difficult problem. This work focuses on lubrication and the resulting energy losses at the sliding interface between the slipper and swashplate. ^ To better understand the slipper lubrication performance, a numerical model has been developed to predict the behavior of a design. The numerical model considers the multi-physics, multi-scale, and transient nature of the lubrication problem by utilizing novel segmented physics solvers and numerical techniques. Partitioned solvers considering the fluid pressure and temperature distributions, structural deformation due to fluid pressure and viscous heating, as well as a solid body dynamics from transient loads have been originally developed and tightly coupled. Although the effort necessary to implement this was significant, by avoiding a more traditional co-simulation approach, high computational efficiency and model fidelity can be achieved. ^ To validate the developed numerical model, a specialized test rig was designed and manufactured. Miniature high-speed inductive position sensors were mounted inside the swashplate of a commercially manufactured pump with only minimal modifications. These six sensors measured the distance between the sensor face and the slipper land as the slipper passed over the sensor, effectively measuring the direct film thickness in real time. The thickness of lubrication represents the greatest unknown predicted by the model and provides the most rigorous validation as well as experimental insight into actual slipper operation. New slippers were installed in the test rig, measured, and then following a period of operation, were measured again. A significant change in film thickness behavior was measured due to the presence of a worn slipper surface during the second period of testing, and this same behavioral change was captured with the simulation model. ^ The developed numerical model was used to conduct case studies demonstrating the potential of virtual pump lubrication design. Slipper sensitivity to operating conditions and materials were explored. Operational changes such as slipper tipping and liftoff at high speeds were numerically observed and would serve to aid a designer in improving the robustness of a design. A multi-modeling approach using a surrogate model based upon a design of experiment study and the full numerical model explored the inter-dependence of variables in a multi-land slipper design. In particular, a decrease in total power loss while increasing the outer stabilizing land width at a constant hydrostatic balance factor was observed for low pressure operatio