Analysis of the Impact Factor of Rail Grinding on Their Condition

The Doctoral Thesis “Analysis of the impact of rail grinding on their condition” is developed by Viktors Ivanovs to obtain a Doctoral Degree in Engineering. The scientific supervisor is Assoc. Professor Dr. sc. ing. Pāvels Gavrilovs. In this Doctoral Thesis rail steels are considered according to standards EN 13674-1:2011 and GOST R 51685-2013. Rail steel defects and reasons for their causes are reviewed. The statistics of damaged and heavily damaged rails in the network “Latvijas dzelzceļš” in the period 2011–2019 is studied and analysed in detail. The statistics of rail grinding train operation in “Latvijas dzelzceļš” within the year period 2011–2019 is gathered and analysed. A research of hardness of 60 E1 type rail running surface, of metal chemical composition of the damaged rail with code X 10.1., and structure analysis was performed. Likewise, statistics of wheelset rejection in the network “Latvijas dzelzceļš” in the period 2016–2019 are gathered and analysed, as well as the number of wheel rim defects in the railway of Russian Federation. The main defects of wheelsets are reviewed. The actual wear of wheels and rails in Latvia and the stated wear in the railway of Russia are modelled. Repair profiles of rail head grinding for Latvian rail ways are modelled and their influence on side wear determined due to the rail and wheel surface interaction. Calculations regarding the wheels with flange angle of 66.8° from worn out profile durability coefficient were performed for Latvian railway according to the entry conditions on rail profiles, developed in this dissertation. A rail grinding method was developed. The wheelset repair and wheel grinding economic expenses were calculated. Recommendations for wheel and rail side wear reduction are presented.

Design Optimization of Diffuser Augmented Wind Turbine

The wind turbine power decreases at low wind speed. A flanged diffuser plays a role of a device for collecting and accelerating the approaching wind, and thus the optimization of the diffuser shape presents an important way to enhance the wind turbine power. In this work, a numerical parametric study was conducted on the diffuser to obtain the initial optimum form of flanged diffuser. Then, the Simplex algorithm is used to obtain the optimal diffuser shape starting from the obtained initial shape. Finally, the obtained optimum diffuser shape is used with conventional wind turbine blade. The diffuser shape is defined by four variables: open angle, flange height, centerbody length, and flange angle. The numerical simulation of flanged diffuser is carried out using the “CFDRC package. The results indicated that, the optimum diffuser shape can be obtained using simplex algorithm which maximizes the entrance average velocity to reach 1.77 times wind speed. The power augmented by a factor about 2.76:5.26 of a selected small wind turbine using the obtained diffuser shape compared to that without diffuser.

Rotational Changes in the Distal Tibial Fragment Relative to the Proximal Tibial Fragment at the Osteotomy Site after Open-Wedge High-Tibial Osteotomy

The present study is aimed at assessing the changes in tibial rotation at the osteotomy site after an open-wedge, high-tibial osteotomy (OWHTO) and analysing the factors that affect rotational changes in the distal tibial fragment relative to the proximal tibial fragment at the same site. This study involved 53 patients (60 knees; 16 males and 37 females) with medial osteoarthritis (OA) who underwent OWHTO and preoperative and 3-month postoperative computed tomography (CT) scans. Rotational angles of the distal tibia were measured using Stryker OrthoMap 3D by comparing preoperative and postoperative CTs. The mean rotational angle yielded an external rotation of 2.9 ° ± 4.8 ° . There were 17 knees with internal rotations, 37 knees with external rotations, and one knee with no rotation. The rotational angle significantly correlated with the resultant change in the femorotibial angle (correction angle) and the angle between the ascending and transverse osteotomy lines on the anterior osteotomised surface on which a flange was formed with the distal tibial osteotomised surface (flange angle). The flange angle affected the rotation, but it may have been affected by our surgical technique. The rotational angle did not significantly correlate with the change in the angle of the posterior tibial slope or body mass index. There were significant correlations between the rotational angle and correction angle ( r = 0.42 , p < 0.05 ). Additionally, the rotational angle correlated with the flange angle ( r = − 0.41 , p < 0.05 ).

Stochastic Analysis of Transit Wheel Wear and Optimized Forecasting of Wheel Maintenance Requirements

As transit vehicle wheels accrue mileage, they experience flange and tread wear based on the contact between the railhead and wheel-running surface. When wheels wear excessively, the likelihood of accidents and derailments increases. Thus, regular maintenance is performed on the wheels, until they require replacement. One common maintenance practice is truing; using a specially designed cutting machine to bring a wheel back to an acceptable profile. This process removes metal from the wheel and is often based on wheel flange thickness standards (and sometimes wheel flange angle). Wheel replacement is usually driven by rim thickness, which is continually reduced by wear and metal removed by truing. This research study used wheel wear data provided by the New York City Transit Authority (NYCTA) to analyze wheel wear trends and forecast wheel maintenance (truing based on flange thickness) and wheel life (replacement based on rim thickness). Using automatic wheel-scanning technology, NYCTA was able to collect wheel profile measurements for nearly 4,000 wheels in its fleet over a six-month period, measured weekly. The resulting wheel measurement data was analyzed using advanced stochastic techniques to determine relationships for the changes in flange thickness over time for each wheel in the fleet. Flange thickness wear rate relationships for each wheel were then used to forecast the time it would take for a wheel to reach the flange thickness maintenance threshold as defined by NYCTA standards. Furthermore, a subpopulation of wheels that exhibited very high rates of wear were classified as “bad actors” and identified for further investigation to understand the cause of accelerated wear. This allows for identification and addressing of causal factors that relate to accelerated wear, such as angle of attack and L/V ratio. NYCTA has recently started capturing such data that relates truck performance, which can be related to rate of wear.

Analysis of process-induced deformation on the spring-in of carbon fiber-reinforced polymer thin laminates

The cure process of carbon fiber-reinforced polymer laminates induces residual stress inside the parts that causes geometrical unconformities. The most important unconformity is the spring-in that means the deviation of the flange-to-flange angle from the design angle. The spring-in value depends on some process parameters, such as the lay-up sequence of the plies, as demonstrated in previous works. The aim of this work is to study the dependence of the spring-in on the deviations in the orientation of the plies due to a hand process. A numerical tool was developed and experimentally tested.

Effect of Gasket Compression Resilience on the Tightness of Bolted Flange System

Gasket is an important sealing element of bolted flange connection structure. The nonlinear performance of the gasket material will make the flange angle and gasket compression force change. Therefore, it plays an important role in the tightness of bolted flange connection system. Apart from acknowledgment of this effect, there exists no established design calculation procedure that accounts for tightness. In this paper, the mechanical properties of the gasket at room temperature were studied, it is known that the rebound performance of the gasket is related to the initial preload. And the effect of the compressive resilience of the gasket on the tightness of the bolt flange system was discussed. The tightness of the bolt flange system can be achieved by adjusting the initial preload and working pressure of the gasket, it provides the basis for design and evaluate the tightness of bolted flange connection system.

Effects of Independently Rolling Wheels on Flange Climb Derailment

The effects of independently rolling wheels (IRW) on flange climb derailment have been investigated through simulations using Transportation Technology Center, Inc. (TTCI)’s *NUCARSTM dynamic modeling software. Simulations of single wheelsets and hypothetcal light rail vehicles equipped with IRWs show that flange angle and flange length parameters play an important role in preventing derailments. That role is especially critical for independent rolling wheels due to their lack of self-steering capability. The speed contour concept was proposed for engineers to adopt the flange angle and flange length in a logical way for wheel profile design in new vehicles and wheel profile maintenance. It is also shown that the sensitivity of IRW to flange climb is also very dependent on particular vehicle designs.