scholarly journals Assessment of Structural Dynamic Response and Vehicle-Track Interaction of Precast Slab Track Systems

2021 ◽  
Vol 11 (8) ◽  
pp. 3558
Author(s):  
Linh Vu ◽  
Dong Doo Jang ◽  
Yun Suk Kang
Keyword(s):  
Numerical Analysis ◽  
Load Transfer ◽  
Structural Response ◽  
Analysis Program ◽  
Train Track ◽  
Structural Dynamic ◽  
Running Safety ◽  
Slab Track ◽  
Train Operation ◽  
Load Transfer Efficiency

Recently, precast slab tracks have been used widely in railway applications, especially in conventional urban railway lines. These types of tracks are rapidly constructed and limit interruptions to train operation. However, the problems of dynamic stability when the trains run on the discontinuous type of tracks must be seriously considered. This paper focuses on analyzing the train-track interaction in two types of tracks under the dynamic load by using the numerical analysis program (APATSI) to evaluate the structural response as well as the running safety to precisely understand the load transfer efficiency of precast slab track systems.

Numerical Analysis of Mechanical Interaction of Pipe-in-Pipe Flowline

2017 ◽  
Author(s):  
M. T. Akolawole ◽  
Yongchang Pu
Keyword(s):  
Numerical Analysis ◽  
Load Transfer ◽  
Structural Response ◽  
Material Model ◽  
Polyamide 6 ◽  
Elastic Response ◽  
Mechanical Interaction ◽  
High Production Rate ◽  
The Impact ◽  
Outer Pipe

Pipe-in-pipe (PIP) flowline is a unique solution for long subsea tie-backs in deepwater and ultra-deepwater fields. This is because of its optimum thermal performance over wet insulation. However, pipelines are subjected to the highest loading condition during installation. Significant limitation imposed on existing installation vessel in deepwater, is peculiar to S-lay installation method. Contrary to the level of stress experienced with the S-lay installation method at specific locations such as overbend and sagbend region, this method is still widely utilized because of its high production rate. These regions are dominated by bending curvatures which are defined by different load conditions. Due to the composition of PIP system, it is important to understand the structural response of the flowline, the mechanical interaction occurring between various components and the amount of load transfer at this location. Although, the mechanical interaction within the PIP system are case specific. However, it has been observed that prior to case study analysis; simple pipe models are being developed to assess the mechanical interaction of this system. This paper addresses the impact of the centralizer material on the structural response and load transfer between the outer pipe and inner pipe. The numerical analysis was carried out using Ansys software and was based on Euler Bernoulli bending theory. The centralizer was clamped on to the inner pipe with the clearance between the centralizer and the outer pipe included in the model. The core of the analysis, was modeling the visco-elastic response of nylon rings (Polyamide 6), from which centralizers are made. The centralizer was spaced based on S-lay or J-lay installation criteria against heat sink. The results demonstrated the relationship between spacing of the centralizer and areas of first contact, amount of force transferred through the centralizer material, non-linearity introduced by contact formulation, alongside the time and temperature dependent behavior of visco-elastic material. The result correlated accurately with the bending principle. Different material model was assessed to determine accuracy of results obtained, in the absence of experimental test data to model visco-elastic response. In addition, the bending curvature was used to predict the mechanical interaction in installation and operation analysis, where limitations of explicitly modeling centralizers exist.

scholarly journals Load Transfer Efficiency Based on Structural Deflection Assessment of the Precast Floating Track

2020 ◽  
Vol 11 (1) ◽  
pp. 120
Author(s):  
Linh Vu ◽  
Yun Suk Kang
Keyword(s):  
Finite Element ◽  
Load Transfer ◽  
Transfer Efficiency ◽  
Element Analysis ◽  
Railway Stations ◽  
Vibration Isolators ◽  
Slab Track ◽  
Test Standards ◽  
Load Carrying ◽  
Load Transfer Efficiency

In Korea, a precast floating track with anti-vibration isolators was recently developed to reduce the vibration and noise in urban railway stations, without disrupting train operations. This precast floating slab track is a newly developed structure and differs from existing conventional slab tracks. In this study, a Finite Element Method program (MIDAS CIVIL 2019) was used to analyze the load-carrying ability of structures under the train axle loads. After finishing the design, to understand more precisely about load transfer efficiency of this type of track, an assembly test (two load cases) was conducted with three precast panels (with rail 60 K mounted on) and compared with Finite Element Analysis results. The final results satisfied the test standards in Korea, which confirms that the precast floating track has an acceptable safety factor and structural behavior.

Deflection-based load transfer efficiency of Floating Slab Track

2014 ◽  
Vol 18 (2) ◽  
pp. 616-624 ◽  
Author(s):  
Wonseok Chung ◽  
Kusung Kwon ◽  
Seung Yup Jang
Keyword(s):  
Load Transfer ◽  
Transfer Efficiency ◽  
Slab Track ◽  
Load Transfer Efficiency

Numerical Analysis of Fire Behavior of a Large Space Pre-Stressed Steel Structure under Fire

2011 ◽  
Vol 71-78 ◽  
pp. 3729-3732
Author(s):  
Ming Zhou ◽  
Zhi Guo Xie ◽  
Xin Tang Wang
Keyword(s):  
Numerical Analysis ◽  
Fire Behavior ◽  
Thermal Response ◽  
Structural Response ◽  
Steel Structure ◽  
Large Space ◽  
Fire Source ◽  
Lattice Shell ◽  
In Fire ◽  
Influence Degree

The computational model of numerical analysis of a suspended pre-stressed steel reticulated shell subjected to fire load is established with using the software Marc. Based on the model presented here, numerical analysis of thermal response and structural response of the pre-stressed steel structure are computed. The different space height and different rise-span ratio are considered for analysis of response temperature, displacements and stresses of the pre-stressed lattice shell under fire for one fire source. It is also shown that displacement of the node right above the inner cable is the maximum among the four nodes presented here as the fire source is located at the position right below the second-ring cable of the structure. It is concluded that the influence degree of space height of the structure on the fire response of the structure is not great, but rise-span ratio has obvious and great effect on displacements and stresses of the pre-stressed steel structure with large span in fire.

scholarly journals Fish Cells, a new zero Poisson’s ratio metamaterial—Part I: Design and experiment

2020 ◽  
Vol 31 (13) ◽  
pp. 1617-1637
Author(s):  
Mohammad Naghavi Zadeh ◽  
Iman Dayyani ◽  
Mehdi Yasaee
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Poisson’S Ratio ◽  
Structural Integrity ◽  
Structural Response ◽  
Poisson's Ratio ◽  
Experimental Investigations ◽  
Fish Cells ◽  
Force Displacement ◽  
Model Approach

A novel cellular mechanical metamaterial called Fish Cells that exhibits zero Poisson’s ratio in both orthogonal in-plane directions is proposed. Homogenization study on the Fish Cells tessellation is conducted and substantially zero Poisson’s ratio behavior in a homogenized tessellation is shown by numerical analysis. Experimental investigations are performed to validate the zero Poisson’s ratio feature of the metamaterial and obtain force–displacement response of the metamaterial in elastic and plastic zone. A detailed discussion about the effect of the numerical model approach and joints on the structural response of the metamaterial is presented. Morphing skin is a potential application for Fish Cells metamaterial because of the integration benefits of zero Poisson’s ratio design. The structural integrity of the Fish Cells is investigated by studying the stiffness augmentation under tension and in presence of constraints on transverse edges. Finally, geometrical enhancements for improved integrity of the Fish Cells are presented that result in substantially zero stiffness augmentation required for morphing skins.

scholarly journals An integrated numerical framework to investigate the running safety of overlong freight trains

2020 ◽  
Vol 235 (1) ◽  
pp. 47-60
Author(s):  
Visakh V Krishna ◽  
Daniel Jobstfinke ◽  
Stefano Melzi ◽  
Mats Berg
Keyword(s):  
Compressive Force ◽  
Radio Communication ◽  
Freight Train ◽  
Running Safety ◽  
Loading Patterns ◽  
Train Operation ◽  
Train Dynamics ◽  
Fail Safe ◽  
P Type ◽  
Brake Block

Long freight trains up to 1500 m in length are currently not in regular operation in Europe. One of the important reasons for the same is high inter-wagon forces generated during the operation, especially when pneumatic (P-type) brake systems are used. For long trains with multiple locomotives at different positions along the train, radio communication with necessary fail-safe mechanisms can be used to apply the brakes. Long freight train operation on a given line is subjected to various attributes such as braking/traction scenarios, loading patterns, wagon geometries, brake-block materials, buffer types, track design geometries, etc., which are referred to as heterogeneities. The complex longitudinal train dynamics arising in the train due to various heterogeneities play a major role in determining its running safety. In this context, the maximum in-train force refers to the maximum force developed between any two wagons along the train during operation. The tolerable longitudinal compressive force is the maximum compressive force that can be exerted on a wagon without resulting in its derailment. Here, the authors adopt a bottom-up approach to model pneumatic braking systems and inter-wagon interactions in multibody simulation environments to study the complex longitudinal train dynamics behavior and estimate maximum in-train forces and tolerable longitudinal compressive forces, subjected to various heterogeneities. These two force quantities intend to facilitate a given freight train operation by providing guidelines regarding the critical heterogeneities, that currently limit its safe operation. In doing so, the authors propose the notion to have an operation-based approval for long freight trains using the simulations-based tool.

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