Study on the Mechanism of Fatigue Failure at Branch Connections Caused by Shell Mode Vibration

2017 ◽  
Author(s):  
Shunji Kataoka
Keyword(s):  
Fatigue Failure ◽  
Design Method ◽  
Acoustic Vibration ◽  
Beam Model ◽  
Stress Concentrations ◽  
Piping Systems ◽  
Mode Vibration ◽  
Rigid Model ◽  
Shell Vibration ◽  
Acoustic Fatigue

Acoustically induced vibration (AIV) is a vibration of piping systems caused by the acoustic loading generated mainly from pressure reducing devices. Recently, the capacities of the pressure reducing systems have been increased and some of the piping systems which are susceptible to acoustic fatigue, such as in flare and depressuring system. Demands on the development of reasonable design method for AIV is increasing. In this paper, the mechanisms of the fatigue failure of branch connection due to AIV were intensively studied. Firstly, the mechanism of the stress concentration was discussed. branch vibration caused by the shell mode vibration was assessed using several branch connection models, massless rigid model, fixed rigid model, and beam model. Next, the relationship between shell-vibration and stress concentrations is studied and re-organized based on acoustic vibration theories. Finally, the risk of the fatigue failure of the branch connection due to acoustic loading was discussed.

Acoustically Induced Structural Fatigue of Piping Systems

1999 ◽  
Vol 121 (4) ◽  
pp. 438-443 ◽  
Author(s):  
F. L. Eisinger ◽  
J. T. Francis
Keyword(s):  
Fluid Pressure ◽  
Acoustic Vibration ◽  
Piping System ◽  
Metal Fatigue ◽  
Hydrocarbon Gases ◽  
Structural Fatigue ◽  
Piping Systems ◽  
Geometry Parameter ◽  
Acoustic Fatigue ◽  
The Relationship

Piping systems handling high-pressure and high-velocity steam and various process and hydrocarbon gases through a pressure-reducing device can produce severe acoustic vibration and metal fatigue in the system. It has been previously shown that the acoustic fatigue of the piping system is governed by the relationship between fluid pressure drop and downstream Mach number, and the dimensionless pipe diameter/wall thickness geometry parameter. In this paper, the devised relationship is extended to cover acoustic fatigue considerations of medium and smaller-diameter piping systems.

Investigation of Design Method for Piping Systems to Prevent Acoustic Fatigue in Process Plants

2002 ◽  
Author(s):  
Itsuro Hayashi ◽  
Teruo Hioki ◽  
Hiroshi Isobe
Keyword(s):  
Pipe Wall ◽  
Interaction Analysis ◽  
Design Method ◽  
Pipe Wall Thickness ◽  
Sound Structure ◽  
Material Fatigue ◽  
Process Plant ◽  
Piping Systems ◽  
Process Plants ◽  
Acoustic Fatigue

Piping systems for steam or gases with a pressure reducing device can cause acoustically induced vibration, resulting in material fatigue failure in process plant. Numerical investigation using sound-structure interaction analysis has been done to find the possible solution to reduce the dynamic stress level in the piping structure. The result shows that reinforcing of the pipe structure such as use of circumferential stiffener rings change the structural characteristic and the maximum stress in the pipe wall. Structural natural frequency is applied to evaluate both effectiveness of reinforcement of pipe structure and the effectiveness of the increase of pipe wall thickness.

Multi Mode Vibration Control and Broder Band Motion Control of Three Dimensional Shaking Table

2005 ◽  
Author(s):  
Tsunehiro Wakasugi ◽  
Toru Watanabe ◽  
Kazuto Seto
Keyword(s):  
Vibration Control ◽  
Controller Design ◽  
Design Method ◽  
Three Dimensional ◽  
Design Procedure ◽  
Equation System ◽  
State Equation ◽  
Shaking Table ◽  
Mode Vibration ◽  
And Control

This paper deals with a new system design method for motion and vibration control of a three-dimensional flexible shaking table. An integrated modeling and controller design procedure for flexible shaking table system is presented. An experimental three-dimensional shaking table is built. “Reduced-Order Physical Model” procedure is adopted. A state equation system model is composed and a feedback controller is designed by applying LQI control law to achieve simultaneous motion and vibration control. Adding a feedforward, two-degree-of-freedom control system is designed. Computer simulations and control experiments are carried out and the effectiveness of the presented procedure is investigated. The robustness of the system is also investigated.

scholarly journals Mechanism and Prevention and Control of Mine Earthquake in Thick and Hard Rock Strata considering the Horizontal Stress Evolution of Stope

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ming Zhang ◽  
Xuelong Hu ◽  
Hongtao Huang ◽  
Guangyao Chen ◽  
Shan Gao ◽  
...  
Keyword(s):  
Hard Rock ◽  
Design Method ◽  
Horizontal Stress ◽  
Prevention Measures ◽  
Stress Concentrations ◽  
Estimation Model ◽  
Working Face ◽  
Mining Design ◽  
And Control ◽  
Rock Strata

This study investigated the mechanism, prevention measures, and control methods for earthquake disasters typically occurring in mines with thick and hard rock strata. A mine stope with large faults and thick hard rock strata in Hebei Province was taken as the background study object. Then, theoretical analysis and numerical simulation methods were adopted in conjunction with field monitoring to explore how horizontal stress evolves in the thick and hard hanging roofs of such mines, potentially leading to mining earthquakes. Then, based on the obtained results, a mining design method was proposed to reduce the horizontal stress levels of earthquake mitigation. The results showed that, under the control of large faults, semiopen and semiclosed stopes with thick hard rock strata are formed, which cause influentially pressurized and depressurized zones during the evolution of the overburden movements and horizontal stress. It was determined that the stress concentrations mainly originated from the release and transfer of horizontal stress during the rock fractures and movements in the roof areas, which were calculated using a theoretical estimation model. The horizontal stress concentrations formed “counter torques” at both ends of the thick and hard strata, which prevented the support ending due to tensile failures. As a result, the limit spans were increased. This study proposed a mining strategy of using narrow working faces, strip mining processes, and reasonable mining speeds, which could effectively reduce horizontal stress concentrations and consequently prevent and control mining earthquakes. This study’s research results were successfully applied to the mining practices in working face 16103.

Performance-Based Analysis of Coupled Support Structures and Piping Systems Subject to Seismic Loading

2015 ◽  
Author(s):  
Oreste S. Bursi ◽  
Fabrizio Paolacci ◽  
Md Shahin Reza
Keyword(s):  
Seismic Design ◽  
Seismic Analysis ◽  
Design Method ◽  
Design Guidelines ◽  
Piping System ◽  
Support Structures ◽  
Limit States ◽  
Piping Systems ◽  
Allowable Stress Design

The prevailing lack of proper and uniform seismic design guidelines for piping systems impels designers to follow standards conceived for other structures, such as buildings. The modern performance-based design approach is yet to be widely adopted for piping systems, while the allowable stress design method is still the customary practice. This paper presents a performance-based seismic analysis of petrochemical piping systems coupled with support structures through a case study. We start with a concept of performance-based analysis, followed by establishing a link between limit states and earthquake levels, exemplifying Eurocode and Italian prescriptions. A brief critical review on seismic design criteria of piping, including interactions between piping and support, is offered thereafter. Finally, to illustrate actual applications of the performance-based analysis, non-linear analyses on a realistic petrochemical piping system is performed to assess its seismic performance.

A Compact Cantilever Model That Includes Fillets

2012 ◽  
Author(s):  
Aarti Chigullapalli ◽  
Jason V. Clark
Keyword(s):  
Radius Of Curvature ◽  
Model Parameters ◽  
Beam Model ◽  
Stress Concentrations ◽  
Feature Size ◽  
Element Analysis ◽  
Size Limitation ◽  
Reducing Stress ◽  
Analytical Expressions ◽  
Typical Model

In this paper we present analytical expressions for determining the stiffness of cantilevers with fillets and tappers. We consider the unavoidable fillet due to the feature size limitation of lithography that rounds acute vertices, and the intentional tapper that is often used for reducing stress concentrations or can be used to reduce the effect of fillets. Previous compact models have not included the stiffness contributions from fillets. However, although fillets are small, they can measurably affect the performance of MEMS by affecting deflection or resonance frequency by their second most significant digit. We extend the well-known analytical beam model to include fillets. To our knowledge, this is the first analytical model of a filleted cantilever. In addition to the typical model parameters of beams, our model also includes process variation overcut and fillet radius of curvature, which are key parameters for MEMS designers. Our analytical solution is within 0.01% of finite element analysis.

Structural Safety Assessment Based on the Fatigue Analysis of the Ice-Resistant Jacket Platforms

2010 ◽  
Author(s):  
Xiaofei Che ◽  
Dayong Zhang ◽  
Qianjin Yue
Keyword(s):  
Risk Assessment ◽  
Fatigue Failure ◽  
Safety Assessment ◽  
Design Method ◽  
Hot Spot ◽  
Cyclic Stress ◽  
Fatigue Analysis ◽  
Structural Safety ◽  
Bohai Bay ◽  
General Process

Most of the ice-resistant jacket platforms in Bohai Sea have been close to or reached their service life. In order to keep the platforms perform safely, a reasonable risk assessment of the existing platforms should be considered. The hazard of the structural fatigue failure under the ice-induced vibrations is so serious, which plays an important role in the safety of the platforms. In this paper, the general process of the structural safety assessment based on the fatigue analysis is established. Firstly, risk assessment of fatigue failure needs to determine whether the cyclic stress of hot-spot induced by ice-vibrations under normal ice condition is so significant. Then, the method of estimating ice-induced fatigue life of existing platforms is developed based on the field data and the safe life design method. Finally, as an application example, the safety assessment of one old jacket platform in Bohai Bay is carried on, which can provide a warrant for owners to repair or reject platforms.

Effect of Longitudinal Fastener Stiffness on Fastening System Loading - Initial Findings

2021 ◽  
Author(s):  
Christian J. Khachaturian ◽  
Marcus S. Dersch ◽  
J. Riley Edwards ◽  
Matheus Trizotto
Keyword(s):  
North America ◽  
Analytical Model ◽  
Fatigue Failure ◽  
Analytical Method ◽  
Vertical Load ◽  
Stress Concentrations ◽  
Laboratory Experimentation ◽  
The Past ◽  
Track Stiffness ◽  
Fatigue Failures

Abstract Over the past 20 years, there have been at least 10 derailments due to spike fatigue failures in North America. Researchers believe that fatigue failure is caused by a combination of lateral and longitudinal spike loading. The literature indicates the vertical load and fastener friction must be considered when estimating failure locations. Though the in-track vertical, lateral, and longitudinal fastener forces have been quantified at a location that has experienced spike failures, there is a need to account for additional fasteners and track locations. Fastening systems can affect track stiffness, thus, laboratory experimentation was performed to quantify stiffness of multiple fastening systems. This data was input into an analytical model which quantified the effect of stiffness on longitudinal fastener loading. The data indicate there is significant variance in fastening system stiffness within, and between, systems. However, this variation in fastener stiffness has a reduced effect on the load transferred to the fastening system. More work is needed to validate this in the lab or field given variability within a system could lead to stress concentrations that are not fully captured using the current idealized analytical method.

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