Military tanks and armored vehicles use tracks with excellent mobility in rough terrain, the transmission, a key component of tracked vehicle driving performance, performs shifting, steering and braking functions of tracked vehicles. There was concern about the deterioration of the driving performance of the tracked vehicle due to the occurrence of oil leakage in the output part of the transmission that rotates the track of the vehicle. Throughㅇ failure mechanism analysis and characteristic factor analysis using 4M(Man, Machine, Material, Method) quality management, it was confirmed that the factor affecting oil leakage in the output part was damage to the output shaft coupling surface, which is the contact surface of the output part oil seal. Based on this, a quality improvement plan was derived by applying a protective cap to prevent damage to the coupling surface, increasing the coupling surface hardness to improve the oil seal sealing function, and revising the work standard throughout production, process movement and assembly stages. The effectiveness of the proposed improvement was verified through a single transmission test, a power pack test, and a track vehicle installation test, and the effectiveness was verified through follow-up observation. It is expected that the improvements derived from this study will be utilized in the future analysis of similar equipment quality problems.

This study presents a systematic causal analysis of the fuel consumption rate reduction phenomenon observed in mortar-carrier tracked vehicles during driving tests. The investigation focused on identifying the root causes and developing effective improvement measures. Through comprehensive inspections and tests of the chassis and power pack components, along with data analysis, the study identified the damage of the engine flywheel housing gasket and the clogging of the transmission exhaust pump strainer as the main causes of the reduced fuel consumption rate. The causal relationship between the two phenomena was empirically proven using material composition analysis and statistical techniques, enhancing the reliability and validity of the diagnosis. Based on the root cause analysis results, improvements were implemented, including the replacement of the engine gasket and the cleaning of the transmission exhaust pump strainer. The effectiveness of the improvements was quantitatively verified, confirming a significant enhancement in fuel consumption rate and cruising range. By employing a systematic and scientific analysis methodology, this study provides a foundation for improving the reliability and maintenance efficiency of similar weapon systems and power transmission systems in general.

In this study, a finite element analysis was used to analyze the stress state and vibration characteristics generated by continuous contact between wheels and rails when driving urban railway vehicles. The rails applied to the analysis were divided into straight and curved shapes, and three-dimensional modeling was performed to analyze the changes in structural characteristics of wheels and rails when driving on straight and curved rails. As a result of the analysis, the stress characteristics were up to 6.5 MPa on a straight rail and 9.81 MPa on a curved rail, and it is believed that this increase in stress will increase noise due to an increase in friction at the interface. The vibration characteristics of the wheels and rails showed similar behavior from the 3rd mode to the 9th mode of the rail to the intrinsic vibration characteristics from the 4th mode to the 6th mode of the wheel.

This study is to investigate the cause of the malfunction of the ground tracked combat vehicle rotating roller and set future direction of improvement. The integrity of the initially used plate and rotating roller was evaluated. As evaluation methods, mechanical property test, radiographic test and size checking test were performed. PA66, PA12, PET, and POM were selected among polymer materials and tested for water absorption rates. Through mechanical property test and radiographic test, the materials used initially were identified to be sound. In the evaluation of the selected four polymer materials, it was confirmed that the PET was excellent in the mechanical properties and the water absorption rate. PET is excellent in mechanical properties and water absorption.

Unlike wheeled vehicles, tracked armored vehicles require a highly developed transmission technology since the transmission has to not only shift gears but also steer and brake the heavy ground weapon system precisely. Even though weapons systems including the K00 Infantry Fighting Vehicle (IFV) have recently been developed with domestic technology, it is true that many core parts in the systems are still being imported. In this paper localization process of the accumulator which is one of the most important hydraulic parts in the K00 transmission is introduced. In order to determine design variables such as operating pressure we analyzed torque characteristics of the transmission and calculated spring constant by disassembling the original accumulator. And tests such as durability, safety, etc. were conducted to assure the validation of the development. We expect that the process of reverse engineering we adopted will be helpful to localize similar hydraulic parts.

ISU (In-arm hydropneumatic Suspension Unit) are popularly applied to recently developed tracked vehicles because of better performance of ISU than the one of the conventional HSU (Hydraulic Suspension Unit). However, function deterioration and malfunction phenomena of the several ISUs were observed due to leakage of hydraulic fluid during operation of the tracked vehicles. The objective of this study is the investigation of fundamental leakage mechanism of hydraulic fluid for the ISU. The leakage mechanism was investigated by comparing both results of the technical data analysis and overhaul inspection of the ISU which occurred leakage of hydraulic fluid. Finally, the leakage mechanism found in the current investigation was verified by using experimental methods.

In this paper, a study on noise reduction characteristics of the precast floating track system, being developed as measures to mitigate noise and vibration of existing as well as constructing elevated railroad stations, is presented using numerical analysis. One of the most prominent sound analysis program, Virtual Lab., is utilized in investigating noise reduction performance of the precast floating track system, and structural velocity data, obtained from vibration analysis on a model-updated elevated railroad station considering vehicle-track-structure interaction, are used for the input of the sound analysis. The sound analysis is performed using the finite element method, and noise reduction performance before and after installing the precast floating track system is compared at three enclosed areas in the Daecheon Station, selected as a representative of elevated railroad stations in this nation. From the comparison result, it is seen that the precast floating track system can decrease noise by average of 5dB∼8dB when the Saemaeul train passing through the station and 10dB∼15dB when the KTX train passing through. Also, the noise reduction characteristics is different depending on the type of train and the distance from the track.

In this paper, interior noise that is brought into inside of coach when it passes by straight line track, railway turnout section, curved track, and rail lubricator section with test coach was measured in accordance of track characteristic of urban railway vehicle. It was evaluated with 60km/h of constant speed in the motorized trailer, no.3 car T1 motorized trailer of urban railway vehicle. Interior noise characteristic value is higher in order of curve, rail lubricator, railway turnout, and straight track as a result of the test. The highest characteristic value is 86.7dB in the curved track. And, the lowest characteristics value is 75.5dB(A) in the straight track. For accurate result comparison, it is transformed into sound pressure distribution by time domain, sound pressure level by time domain, sound pressure level for frequency domain and completed analysis.

철도교량은 차량과 교량의 상호작용에 의해 유발되는 동하중을 받고 있다. 이러한 동적인 효과는 교량 각 부재에 충격과 피로를 유발하고, 교량의 잔존수명에 영향을 미치게 된다 따라서 수치적 또는 시험적 방법에 의한 교량의 실제적인 동적 거동을 분석하는 것이 매우 중요하다. 본 논문에서는 KTX 차량의 주행에 따른 교량의 동적 특성을 구조적 안전성, 주행 안전성 및 승차감 측면에서 평가할 수 있는 차량/궤도/교량 상호작용 해석프로그램을 개발하였다. 차량/궤도/교량의 실질적인 모델링을 위하여 차륜/레일 접촉 모델링을 위한 헤르찌안 스프링 및 도상에 대한 윈클러 요소를 적용하였다. 또한 개발 프로그램은 준3차원해석으로 차량의 복선제도 주행에 따른 3차원 편심 효과를 고려하기 위해 비톤 자유도 및 기하학적인 관계에 따른 제약조건식을 사용하였다. 개발프로그램의 검증을 위해서 고속철도교량중 가장 일반적인 형식인 PSC 박스교(2@40m=80m)에 대해 수치해석결과 및 계측시험 결과를 비교하였다.

본 연구에서는 ANSYS와 ABAQUS 상용 유한요소 코드를 이용하여 궤도차량의 정적.동적 해석을 충격하중과 주행하중에 대해서 수행하였다. 궤도차량이 충격하중을 받을 때 최대 동적 Von Mises응력은 상판의 빔보강재와 레이스링사이에서 발생하였으며 응력수준은 390-450MPa이다. 정하중에 대한 동하중수 1.6을 고려했을 경우 동적 해석과 동적하중계수가 포함된 정하중 해석은 유사한 결과를 보이고 있다. 과도응력은 주로 레이싱링 주위에서 발생하고 있다. 주행하중의 경우 최대응력은 로드휠 유기압 현가장치 #1번에서 450MPa정도이며, 정적해석과 비선형 해석의 결과가 유사하다.

In this study, a contact node and a penalty spring were introduced at the bottom of the contact spring, and the track irregularity effect was implemented. Through this present approach, the non-linearity of the contact spring can be expressed using non-linear spring elements of ANSYS itself. The applicability of the improved analysis technique has been verified through various demonstrated cases. A stable solution was obtained even for a problem where the contact spring’s non-linearity changed rapidly.