An Accurate Spatial Discretization and Substructure Method With Application to Moving Elevator Cable-Car Systems—Part II: Application

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
H. Ren ◽  
W. D. Zhu
Keyword(s):  
Linear Model ◽  
Axial Force ◽  
Linear Models ◽  
Coupled Model ◽  
Bending Moment ◽  
Current Method ◽  
Coupled Vibrations ◽  
Length Variant ◽  
Suspension Cable ◽  
Elevator Cable

This paper uses the methodology developed in Part I of this work to study the longitudinal, transverse, and their coupled vibrations of moving elevator cable-car systems. A suspension cable is a one-dimensional length-variant distributed-parameter component. When there is only one suspension cable connected to the car, the car is modeled as a point mass. When there are multiple suspension cables, the car is modeled as a rigid body, and the rotation of the car is considered. There are complicated matching conditions between the cable and car, which cannot be satisfied in the classical assumed modes method but can be satisfied in the current method. Hence, not only the longitudinal and transverse displacements but also the internal forces/moment, such as the axial force, the bending moment, and the shear force, which are related to the spatial derivatives of the longitudinal and transverse displacements, are accurately calculated. The results from different choices of boundary motions and trial functions are essentially the same, and the convergence is much faster than that of the assumed modes method. The longitudinal-transverse coupled vibrations of a moving cable-car system are also studied using the current method, and the results are compared with those from the linear models. While the result from the linear model for the transverse vibration agrees well with that from the nonlinear coupled model, the axial force from the linear model can significantly differ from that from the nonlinear model when the car approaches the top of the hoistway.

An Accurate Spatial Discretization and Substructural Method With Application to Moving Elevator Cable-Car Systems: Part II—Application

2011 ◽  
Author(s):  
H. Ren ◽  
W. D. Zhu
Keyword(s):  
Linear Model ◽  
Axial Force ◽  
Linear Models ◽  
Coupled Model ◽  
Bending Moment ◽  
Current Method ◽  
Coupled Vibrations ◽  
Length Variant ◽  
Suspension Cable ◽  
Elevator Cable

This paper uses the methodology developed in Part I of this work to study the longitudinal, transverse, and their coupled vibrations of moving elevator cable-car systems. A suspension cable is a one-dimensional length-variant distributed-parameter component. When there is only one suspension cable connected to the car, the car is modeled as a point mass. When there are multiple suspension cables, the car is modeled as a rigid body, and the rotation of the car is also included. There are complicated matching conditions between the cable and the car, which cannot be satisfied in the classical assumed modes method, but can be satisfied in the current method. Hence not only the longitudinal and transverse displacements, but also the internal forces/moment, such as the axial force, the bending moment, and the shear force, which are related to the spatial derivatives of the longitudinal and transverse displacements, are accurately calculated. The results from different choices of boundary motions and trial functions are essentially the same, and the convergence is much faster than that of the assumed modes method. The longitudinal-transverse coupled vibrations of a moving cable-car system are also studied using the current method, and the results are compared with those from the linear models. While the result from the linear model for the transverse vibration agrees well with that from the nonlinear coupled model, the axial force from the linear model can significantly differ from that from the nonlinear model when the car approaches the top of the hoistway.

scholarly journals Analysis of a Linear Model for Non-Synchronous Vibrations Near Stall

2021 ◽  
Vol 6 (3) ◽  
pp. 26
Author(s):  
Christoph Brandstetter ◽  
Sina Stapelfeldt
Keyword(s):  
Linear Model ◽  
Linear Models ◽  
Structural Vibration ◽  
Experimental Investigations ◽  
Vibration Modes ◽  
Critical Problem ◽  
Safety Critical ◽  
Unstable Vibration ◽  
Aero Engines ◽  
Lock In

Non-synchronous vibrations arising near the stall boundary of compressors are a recurring and potentially safety-critical problem in modern aero-engines. Recent numerical and experimental investigations have shown that these vibrations are caused by the lock-in of circumferentially convected aerodynamic disturbances and structural vibration modes, and that it is possible to predict unstable vibration modes using coupled linear models. This paper aims to further investigate non-synchronous vibrations by casting a reduced model for NSV in the frequency domain and analysing stability for a range of parameters. It is shown how, and why, under certain conditions linear models are able to capture a phenomenon, which has traditionally been associated with aerodynamic non-linearities. The formulation clearly highlights the differences between convective non-synchronous vibrations and flutter and identifies the modifications necessary to make quantitative predictions.

Closed-form moment-curvature relations for reinforced concrete cross sections under bending moment and axial force

2016 ◽  
Vol 129 ◽  
pp. 67-80 ◽  
Author(s):  
Pedro Dias Simão ◽  
Helena Barros ◽  
Carla Costa Ferreira ◽  
Tatiana Marques
Keyword(s):  
Reinforced Concrete ◽  
Closed Form ◽  
Axial Force ◽  
Cross Sections ◽  
Bending Moment

Preliminary Parametric Assessment of a Bolted Endplate Joint under Combined Axial Force and Cyclic Bending Moment

2011 ◽  
Vol 255-260 ◽  
pp. 718-721
Author(s):  
Z.Y. Wang ◽  
Q.Y. Wang
Keyword(s):  
Finite Element Analysis ◽  
Axial Force ◽  
Seismic Design ◽  
Axial Load ◽  
Failure Modes ◽  
Bending Moment ◽  
Element Analysis ◽  
Cyclic Behaviour ◽  
Joint Behaviour ◽  
Steel Joints

Problems regarding the combined axial force and bending moment for the behaviour of semi-rigid steel joints under service loading have been recognized in recent studies. As an extended research on the cyclic behaviour of a bolted endplate joint, this study is performed relating to the contribution of column axial force on the cyclic behaviour of the joint. Using finite element analysis, the deteriorations of the joint performance have been evaluated. The preliminary parametric study of the joint is conducted with the consideration of flexibility of the column flange. The column axial force was observed to significantly influence the joint behaviour when the bending of the column flange dominates the failure modes. The reductions of moment resistance predicted by numerical analysis have been compared with codified suggestions. Comments have been made for further consideration of the influence of column axial load in seismic design of bolted endplate joints.

scholarly journals A Cascaded Unsupervised Model for PoS Tagging

2021 ◽  
Vol 20 (1) ◽  
pp. 1-23
Author(s):  
Necva Bölücü ◽  
Burcu Can
Keyword(s):  
Linear Model ◽  
Language Processing ◽  
Bayesian Model ◽  
Linear Models ◽  
Syntactic Category ◽  
Semantic Parsing ◽  
Pos Tagging ◽  
Part Of Speech ◽  
Sentence Level ◽  
Log Linear

Part of speech (PoS) tagging is one of the fundamental syntactic tasks in Natural Language Processing, as it assigns a syntactic category to each word within a given sentence or context (such as noun, verb, adjective, etc.). Those syntactic categories could be used to further analyze the sentence-level syntax (e.g., dependency parsing) and thereby extract the meaning of the sentence (e.g., semantic parsing). Various methods have been proposed for learning PoS tags in an unsupervised setting without using any annotated corpora. One of the widely used methods for the tagging problem is log-linear models. Initialization of the parameters in a log-linear model is very crucial for the inference. Different initialization techniques have been used so far. In this work, we present a log-linear model for PoS tagging that uses another fully unsupervised Bayesian model to initialize the parameters of the model in a cascaded framework. Therefore, we transfer some knowledge between two different unsupervised models to leverage the PoS tagging results, where a log-linear model benefits from a Bayesian model’s expertise. We present results for Turkish as a morphologically rich language and for English as a comparably morphologically poor language in a fully unsupervised framework. The results show that our framework outperforms other unsupervised models proposed for PoS tagging.

Load Regime Diagram of a Pipe With Cyclically Plastic Bending

2002 ◽  
Author(s):  
Yanping Yao ◽  
Ming-Wan Lu
Keyword(s):  
Axial Force ◽  
Bending Moment ◽  
Boundary Curve ◽  
Plastic Behavior ◽  
Cyclic Bending ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Load Regime ◽  
Reversed Cyclic ◽  
Cyclic Bending Moment

The criteria of piping seismic design based on linear elastic analysis has been proved to be conservative, which is mainly because the influence of plastic deformation on piping dynamic response is neglected. In the present paper, a pipe under seismic excitation is simplified as an beam with tubular cross section subjected to steady axial force and fully reversed cyclic bending moment, and the elastic-plastic behavior of the pipe is studied. Various behavior of the pipe under different combinations of axial force and cyclic bending moment is discussed and the boundary curve equations between them are obtained. Also the load regime diagram for a pipe which is formed by the boundary curve equations in the loading plane is given, from which the elastic-plastic behavior of the pipe can be determined directly.

A Simple Approach for Including Weld Residual Stresses in the Calculation of Pipe Circumferential Through-Wall Crack Opening Displacements

2016 ◽  
Author(s):  
Richard Olson
Keyword(s):  
Residual Stresses ◽  
Axial Force ◽  
Analytic Solution ◽  
Crack Opening ◽  
Bending Moment ◽  
Generalized Solution ◽  
Finite Element Analyses ◽  
Opening Displacement ◽  
Crack Face ◽  
Basic Equations

Current methodologies for predicting the crack opening displacement (COD) of circumferentially through-wall cracked pipe do not include the effect of weld residual stresses (WRS). Even the most advanced COD prediction methodology only includes the effect of applied axial force, bending moment, and crack face pressure. For some years, it has been known that weld residual stresses do alter the COD, but there has been no convenient way to include them in a COD prediction without doing case-specific finite element analyses. This paper documents a generalized solution for including WRS effects on COD. The model uses a closed-form analytic solution to approximate the crack face rotations that the WRS would induce which, subsequently, can be added to the typical axial force-bending-crack face pressure COD solution. The methodology is described and the basic equations for the solution are presented. Following this, application to cases to evaluate the efficacy of the approach are presented which show a mixture of results ranging from amazingly good to “of questionable value” with respect to the FEA results.

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