Applied Mechanics and Materials Vols. 809-810

Abstract: Currently much of the specialized programs in computer aided design (CAD) have incorporated into their structure a module of simulation and analysis. With these modules it can be simulated the operation of the various drawings equipment in the 3D format and to analyze critical areas of its. Using these modules allows a quick assessment of design to equipment’s. This paper presents a finite element static analysis on current collector components used on the locomotive LE 060 EA used in Romania. It’s considered the situation given by EP3 pantograph located at maximum height.

Abstract: The prediction of polymer properties, based on its composition, it is a complex problem with no easy method to obtain directly and accurately results. Among the tribological properties, the friction coefficient and wear rate are the most interesting ones. The polymers based on epoxy resin, with clay as filler, show different properties depending on the clay concentration. This paper presents an analysis of the polymer properties variation with its filler concentration. Due to the tribological processes complexity, mechanical and thermal properties must be taken into account. The aim of this study is to find an optimal concentration value, with minimal influence on polymer properties. All value properties will be used in a neural network model in order to optimize and predict the composite properties.

Abstract: Friction coefficient and linear wear rate of polyester-carbon nanotubes composites were investigated through ball-on-flat reciprocating test, under dry sliding contact. Three types of nanoscopic fillers were used: multiwall carbon nanotubes (MWCNT), functionalized multiwall carbon nanotubes (MWCNT-COOH) and singlewall carbon nanotubes (SWCNT), with three values of weight content 0.1, 0.15 and 0.2 wt%. Comparative analysis was done for polyester and its composites tested over 14 m sliding distance, under three values of load, 30 N, 40 N and 50 N. Composites containing MWCNT underwent a decrease in friction coefficient and linear wear rate only in case of 50N loading. An improvement of wear behavior under 50N loading was obtained for the composite with 0.10 wt% functionalized carbon nanotubes. Generally, better values of wear rate at 50 N loading were recorded in case of composites with 0.15 wt% and 0.20 wt% MWCNT and SWCNT, respectively. Optical and electronic investigation of the worn surfaces revealed the occurrence of abrasive, adhesive and fatigue wear. Abrasive wear is due to the hard particles detached from the counterpart which produce scratches and furrows on sliding track. Adhesive wear results when soft particle of polymer are caught and blocked among the asperities of counterpart, and it develops over a local area, being influenced by temperature rise. Fatigue and abrasive wear are responsible for the formation of the 3^rd body between contacting parts which affects the friction and wear behavior. Morphological analysis of worn surface showed the rise of transfer film that induces instability of wear parameters.

Abstract: The distribution and the size of longitudinal dynamic forces that develop in the train body found in braking system are influenced by the length of the train. To determine these forces, it is used a mechanical model consisting of rigid bodies, representing the train vehicles, connected by elastic and damping elements with the nonlinear characteristic that shapes the buffer and draw-gear. The results based on numerical simulations highlight the emergence of dynamic longitudinal forces during braking, their evolution over time and the distribution of maximum compression and stretching forces that develop in buffer and draw-gear devices, for different lengths of the passenger train.

Abstract: In order to better protect the engine, air filters with high efficiency should be used as well as appropriate maintenance activities. Maintenance activity must take into account the behaviour of the air filters during exploitation, namely the increases of the gaso-dynamic resistances they produce while air filters are used. This paper presents the variation of the pressure restriction depending on the amount of dust retained by the air filters and also the storage capacity of dust by the air filters. Filters are loaded on a laboratory rig with dust from the roads of Bucharest.

Abstract: Concerned challenge of road safety in research and development, most automotive companies develops more than 50 years, technologies that improve the safety of their vehicles presented. Most research is based on studies carried out in the laboratories accidentology and analysis of human behavior to improve biofidelity test these models in order to develop the most effective equipment to investigate real-life situations that can arise on the road. There are programs on road safety designed around four key areas: prevention, correction, protection and awareness. If, in the best case to protect in case of an incident is crucial to avoid the accident is an absolute priority. Studies show that human error is the basis of 80% of all cases occurring in road events [1]. Today, automotive companies never cease to develop new safety devices which prevent an accident or to protect the passengers. Elections conducted safety relies on a greater degree of prevention, more anticipation, the driver is still the factor responsible for the act of driving Extremely complex, however, and the body structure and reactivity to shock [2]. Shock response is broad and consists of biomechanical response and neuro major spending in the immediate care and rehabilitation.

Abstract: paper presents a case study of ships passing through shallow and narrow waters in Sulina Channel. The method used in this research was simulation using NTPRO 5000 navigational simulator and it was studied the variation of ship squat, draft and under keel clearance for several military ships similar to Romanian Navy vessels, sailing with different speeds. The purpose of this research was to find out which ship types could navigate through Sulina Channel and what is the maximum speed they could pass without grounding due to ship squat. The integration of the trials results showed what the safe speed for each vessel was and it was concluded that the maximum speeds were 8, 12, and 16 knots. Also, a difference between desired and real speed was observed, caused by the restrictive navigation condition. Numerous researches are being done in ship squat domain and Sulina Channel is one of the canals where this phenomenon is studied, but squat simulation on military ships has never been done before in this canal.

Abstract: In the recent decades, the vehicle lighweighting problem has been addressed through various methodologies by different researchers and industries. Significant effort has been made recently to develop lightweight structural solutions by employing state-of-the-art and emerging materials, manufacturing processes and technologies. The presented research aimed to investigate the possibility of designing vehicle lightweight structures using advanced steel grades and novel structural profiles developed by industry by integrating smart design and manufacturing solutions. A case study was developed in the presented paper on a freight wagon structure. The structural stress analysis of the new lightweight design has been carried out through Finite Element Analysis (FEA) for validating the proposed solutions. The FEA considered the standard loading scenarios, taking into account both the static and dynamic operational loads, and the results were evaluated against the traditional design of a similar benchmark homologated vehicle. The results demonstrate that novel steel products can be successfully employed for designing sustainable and feasible lightweight vehicle structures.

Abstract: The engine air supply system is the main source through which impurities from the atmosphere reach inside the kinematic couplings of the engine. The engine protection is ensured by periodically replacement of the air filters. Determining air filters service life is a difficult problem due to different operation conditions of the vehicles. Therefore, air filters are frequently replaced more often than necessary on the principle that a new filter is better than a replaced one. The present paper aims to determine if the air filters replaced during the preventive maintenance activities have reached the end of their service life or they could still be used. The research is based on measuring the pressure restriction and estimating the mass of dust collected by the air filters.

Abstract: Preparing the task for the robotic system takes several steps. Programming a robot, as the last step, is preceded by the analysis of possible variants of its implementation and trajectory planning. However, the first step is to recognize the task and to split it into fragments, according to activity, without the reference how to realize them. The modern robotics seeks the way to shorten the time to of program preparation, developing the so-called "programming at the task level." It consists in writing a program in a language, which is similar to natural one, describing only the basic operations, without going into the details of their realization the robot (like collision-free path selection or communication with the environment through interfaces and sensors). The outcome is, for example the special voice interfaces used in robotized surgery that allow the surgeon to cooperate with assisting robot without the need to divert their attention from the surgical field. In case of industrial robots, this method is treated as the experimental one and the interest is confined to purely scientific. This article discusses some aspects of this method with respect to the first stages of the task planning. A description of the robot’s workspace and defining the basic steps in a language which is similar to natural one, allows the use of logic programming language to generate pseudocode, which eventually leads to the realization of the task. Every activity could be then divided into elementary steps that must be described directly in the robot programming language. The presented method is currently at the early stage of development and does not allow the direct programming of the robot, but the generated pseudocode could be the basis of a complete program.