Stochastic Response of Piping Systems With Flexible Supports

1996 ◽  
Vol 118 (1) ◽  
pp. 109-114 ◽  
Author(s):  
H. O. Soliman ◽  
T. K. Datta
Keyword(s):  
Frequency Domain ◽  
Cross Sections ◽  
Equations Of Motion ◽  
Response Analysis ◽  
Piping System ◽  
Dynamic Stresses ◽  
Support Points ◽  
Flexible Supports ◽  
Piping Systems ◽  
Support Excitation

A frequency domain spectral analysis of piping systems with flexible supports is presented for uniformly modulated nonstationary support excitations. The support points are idealized by spring-dashpot arrangements. The equations of motion of the resulting nonclassically damped, multipoint excitation system are written and solved in terms of the absolute displacements of the dynamic DOF. This facilitates a direct computation of the dynamic stresses induced at various cross sections of the pipe segments. The method of analysis provides a quasi-stationary response based on the assumption that the modulating function varies slowly with time; the exact response analysis in frequency domain for such systems with nonstationary support excitation is difficult to determine. Using the method of analysis presented, the response of a piping system is obtained for a set of important parametric variations related to the flexibility, damping, and excitation of the supports.

Frequency Domain Analysis of Vibrations in Liquid-Filled Piping Systems

1999 ◽  
Author(s):  
Zongxia Jiao ◽  
Qing Hua ◽  
Kai Yu
Keyword(s):  
Frequency Domain ◽  
Transfer Matrix ◽  
Fluid Structure Interaction ◽  
Viscous Friction ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Piping System ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Piping Systems

Abstract In the analysis of liquid-filled piping systems there are Poisson-coupled axial stress waves in the pipe and liquid column, which are caused by the dilation of the pipe. In some conditions the influence of viscous friction that is usually frequency-dependent should not be omitted, which in fact is another kind of coupled form. It directly influences the amplitude of vibration of piping systems to some degree. The larger the viscosity of the liquid is, the greater the influence will be. Budny (1991) included the viscous friction influence in time domain analysis of fluid-structure interaction, but did not give frequency domain analysis. Lesmez (1990) gave the model analysis liquid-filled piping systems without considering friction. If the friction is not included in frequency domain analysis, the vibration amplitude will be greater than that when friction is included, especially at harmony points, cause large errors in the simulation of fluid pipe network analysis, although it may have little influence on the frequency of harmony points. The present paper will give detail solutions to the transfer matrix that represents the motion of single pipe section, which is the basis of complex fluid-structure interaction analysis. Combined with point matrices that describe specified boundary conditions, overall transfer matrix for a piping system can be assembled. Corresponding state vectors can then be evaluated to predict the piping and liquid motion. At last, a twice-coordinate transformation method is adopted in joint coupling. Consequently, the vibration analysis of spatial liquid-filled piping systems can be carried out. It is proved to be succinct, valid and versatile. This method can be extended to the simulation of the curved spatial pipeline systems.

A Method for the Frequency Domain Seakeeping Analysis of Offshore Structures in the Early Design Stage

2020 ◽  
Author(s):  
Maximilian Liebert
Keyword(s):  
Frequency Domain ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Offshore Structures ◽  
Design Stage ◽  
Design Environment ◽  
Early Design ◽  
Early Design Stage ◽  
Response Amplitude Operators

Abstract The motion analysis of floating offshore structures is a major design aspect which has to be considered in the early design stage. The existing design environment E4 is an open software framework, which is being developed by the Institute of Ship Design and Ship Safety, comprising various methods for design and analysis of mainly ship-type structures. In context of the development to enhance the design environment E4 for offshore applications this paper presents a method to calculate the response motions of semi-submersibles in regular waves. The linearised equations of motion are set up in frequency domain in six degrees of freedom and the seakeeping behaviour is calculated in terms of the amplitudes of the harmonic responses. The hydrodynamic forces onto the slender elements of the semi-submersible are accounted for by a Morison approach. As the drag and damping forces depend quadratically on the amplitudes, these forces are linearised by an energy-equivalence principle. The resulting response amplitude operators of the semi-submersible are validated by comparison with model tests. The method represents a fast computational tool for the analysis of the seakeeping behaviour of floating offshore structures consisting of slender elements with circular cross sections in the early design stage.

Multiharmonic Forced Response Analysis of a Turbine Blading Coupled by Nonlinear Contact Forces

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Christian Siewert ◽  
Lars Panning ◽  
Jörg Wallaschek ◽  
Christoph Richter
Keyword(s):  
Frequency Domain ◽  
Nonlinear Equations ◽  
Forced Response ◽  
Vibration Response ◽  
Contact Forces ◽  
Dynamic Loads ◽  
Response Analysis ◽  
Dynamic Stresses ◽  
Nonlinear Contact ◽  
Turbine Blading

In turbomachinery applications, the rotating turbine blades are subjected to high static and dynamic loads. The static loads are due to centrifugal stresses and thermal strains whereas the dynamic loads are caused by the fluctuating gas forces resulting in high vibration amplitudes, which can lead to high cycle fatigue failures. Hence, one of the main tasks in the design of turbomachinery blading is the reduction in the blade vibration amplitudes to avoid high dynamic stresses. Thus, coupling devices like underplatform dampers and tip shrouds are applied to the blading to reduce the vibration amplitudes and, therefore, the dynamic stresses by introducing nonlinear contact forces to the system. In order to predict the resulting vibration amplitudes, a reduced order model of a shrouded turbine blading is presented including a contact model to determine the nonlinear contact forces. To compute the forced response, the resulting nonlinear equations of motion are solved in the frequency domain using the multiharmonic balance method because of the high computational efficiency of this approach. The transformation from the time domain into the frequency domain is done by applying Galerkin’s method in combination with a multiharmonic approximation function for the unknown vibration response. This results in an algebraic system of nonlinear equations in the frequency domain, which has to be solved iteratively in order to compute the vibration response. The presented methodology is applied to the calculation of the forced response of a nonlinear coupled turbine blading in the frequency domain.

scholarly journals Comparison of ICEPEL Predictions With Single-Elbow Flexible Piping System Experiment

1979 ◽  
Vol 101 (2) ◽  
pp. 142-148 ◽  
Author(s):  
M. T. A-Moneim ◽  
Y. W. Chang
Keyword(s):  
Stainless Steel ◽  
Circumferential Strain ◽  
Structural Response ◽  
Response Analysis ◽  
Piping System ◽  
System Experiment ◽  
Stainless Steel Pipe ◽  
Piping Systems ◽  
In Series ◽  
Nickel 200

The ICEPEL Code for coupled hydrodynamic-structural response analysis of piping systems is used to analyze an experiment on the response of flexible piping systems to internal pressure pulses. The piping system consisted of two flexible Nickel-200 pipes connected in series through a 90-deg thick-walled stainless steel elbow. A tailored pressure pulse generated by a calibrated pulse gun is stabilized in a long thick-walled stainless steel pipe leading to the flexible piping system which ended with a heavy blind flange. The analytical results of pressure and circumferential strain histories are discussed and compared against the experimental data obtained by SRI International.

Dynamic Response of a Piping System Under Harmonic Excitations Considering Pipe-Support Friction With Variable Normal Loads

2013 ◽  
Author(s):  
José Argüelles ◽  
Euro Casanova
Keyword(s):  
Equations Of Motion ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Dynamic Loads ◽  
Computational Time ◽  
Integration Scheme ◽  
Piping System ◽  
Harmonic Excitations ◽  
Piping Systems ◽  
Support Surfaces

Dynamic loads in piping systems are mainly caused by transient phenomena generated by operating conditions or installed equipment. In most cases these dynamic loads may be modeled as harmonic excitations e.g. pulsating flow. On the other hand, when designing piping systems under dynamic loads, it’s a common practice to neglect strong nonlinearities such as shocks and friction between pipe and support surfaces, mainly because of the excessive cost in terms of computational time and the complexity associated with the integration of the nonlinear equations of motion. However, disregarding these nonlinearities for some systems may result in overestimated dynamic amplitudes leading to incorrect analysis and designs. This paper presents a numerical approach to calculate the steady-state response amplitudes of a piping system subject to harmonic excitations and considering dry friction between the pipe and the support surfaces, without performing a numerical integration. The proposed approach permits the analysis of three dimensional piping systems where the normal forces may vary in time and is based in the Hybrid Frequency-Time Domain method (HFT). Results of the proposed approach are compared and discussed with those of a full integration scheme, confirming that HFT is a valid and computationally feasible option.

Simplified Seismic Response Analysis Method Using Reduced Model of Piping System

2018 ◽  
Author(s):  
Michiya Sakai ◽  
Ryuya Shimazu ◽  
Shinichi Matsuura ◽  
Ichiro Tamura
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Seismic Response ◽  
Degrees Of Freedom ◽  
Response Analysis ◽  
Piping System ◽  
Element Analysis ◽  
Mass System ◽  
Piping Systems ◽  
Low Degrees

In the seismic response analysis of piping systems, finite element analysis is performed with analysis method guidelines [1]–[4] established based on benchmark analysis. However, since it takes a great deal of effort to carry out finite element analysis, a simplified method to analyze the seismic response of complex piping systems is required. In this research, we propose a method to reduce an equivalent spring-mass system model with low degrees of freedom, which can take into account the main mode of the complicated piping system. Simplified seismic evaluation is carried out using this spring mass system model with low degrees of freedom, and the accuracy of response evaluation is confirmed by comparison with finite element analysis.

Application of JSME Seismic Code Case by Elastic-Plastic Response Analysis to Practical Piping System

2018 ◽  
Author(s):  
Akihito Otani ◽  
Satoru Kai ◽  
Naoaki Kaneko ◽  
Tomoyoshi Watakabe ◽  
Masanori Ando ◽  
...  
Keyword(s):  
Seismic Design ◽  
Evaluation Methodology ◽  
Design Rule ◽  
Design Evaluation ◽  
Response Analysis ◽  
Piping System ◽  
Plastic Response ◽  
Seismic Code ◽  
Elastic Plastic ◽  
Piping Systems

A Code Case in the framework of JSME Nuclear Codes and Standards is being developed to incorporate a seismic design evaluation methodology for piping by means of advanced elastic-plastic response analysis methods and strain-based fatigue criteria. The Code Case as an alternative seismic design rule over the current rule will provide a more rational seismic design evaluation than the current criteria. This paper demonstrates an application result of the JSME Seismic Code Case to an actual complex piping system. The secondary coolant piping system of Japanese Fast Breeder Reactor, Monju, was selected as a representative of the complex piping systems. The elastic-plastic time history analysis for the piping system was performed and the piping system has been evaluated according to the JSME Seismic Code Case. The evaluation by the Code Case provides a reasonable result in terms of the piping fatigue evaluation that governs seismic integrity of piping systems. Moreover, it is found that the supporting forces and the response accelerations of the piping system obtained by the elastic-plastic response analysis also become more rational results than those with the current elastic response analysis. The contradiction of two requirements in piping design, flexibility for thermal expansion and rigidity for seismic response, can be effectively relaxed by use of the Code Case being developed.

Seismic Proving Test of Ultimate Piping Strength: Simulation Analysis of Simplified Piping System Test

2003 ◽  
Author(s):  
Kenichi Suzuki ◽  
Y. Namita ◽  
H. Abe ◽  
I. Ichihashi ◽  
Kohei Suzuki ◽  
...  
Keyword(s):  
Large Scale ◽  
Simulation Analysis ◽  
Safety Margin ◽  
Response Analysis ◽  
Piping System ◽  
Seismic Safety ◽  
Strain Behavior ◽  
Critical Elements ◽  
Seismic Design Code ◽  
Piping Systems

The six-year program for the Seismic Proving Test of Ultimate Piping Strength has been running since 1998 with the following objectives: i) to clarify the elasto-plastic response and ultimate strength of nuclear piping, ii) to ascertain the seismic safety margin of the current seismic design code for piping, and iii) to assess new allowable stress rules. To resolve outstanding technical issues before proceeding on to a seismic proving test of a large-scale piping system, a series of preliminary tests of materials, piping components and simplified piping systems is intended. A simulation analysis related to the simplified piping system test is described with a focus on the methodology of the non-linear dynamic response analysis of the whole piping system and the strain behavior of the localized critical elements, such as elbows and nozzles.

Seismic Response Analysis of Multiple Supported Piping System Considering Friction Characteristics of Support

2011 ◽  
Author(s):  
Akira Sone ◽  
Kazumasa Tsuchikawa ◽  
Tatsuya Yamauchi ◽  
Arata Masuda
Keyword(s):  
Practical Method ◽  
Reduction Factor ◽  
Maximum Response ◽  
Response Analysis ◽  
Piping System ◽  
Petrochemical Plant ◽  
Maximum Acceleration ◽  
Friction Characteristics ◽  
Response Reduction Factor ◽  
Piping Systems

In this study, a practical method for obtaining the nonlinear seismic maximum response properties of multiple supported piping systems with friction characteristics in industrial plants such as the nuclear power plant and petrochemical plant is presented. In this method, the response reduction effects of friction are effectively considered. The method also facilitates the calculation of maximum nonlinear responses by using those of the linear piping-supporting system. By numerical simulations with a simple 2DOF model, the reduction effect of friction on the maximum acceleration responses of multiple supported piping systems are evaluated in terms of “response reduction factor”. After summarizing the characteristics of the response reduction factor obtained for various system parameters, a practical method for obtained this factor using the maximum linear response of piping system can be introduced. Finally, the maximum response calculated by the proposed method is presented for practical use.

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