Impact Work-Rate and Wear of a Loosely Supported Beam Subject to Harmonic Excitation

2002 ◽  
Author(s):  
Jakob Knudsen ◽  
Ali R. Massih
Keyword(s):  
Companion Paper ◽  
Harmonic Excitation ◽  
Work Rate ◽  
Fretting Wear ◽  
Process Time ◽  
Wear Process ◽  
Stable Attractor ◽  
Wear Damage ◽  
Wear Law ◽  
The Impact

Impact work-rate of a weakly damped beam with elastic two-sided amplitude constraints subject to harmonic excitation is calculated. Impact work-rate is the rate of energy dissipation to the impacting surfaces. The beam is clamped at one end and constrained by unilateral contact sites near the other end. This system was an object of a vibro-impact experiment which was analyzed in our earlier paper (Knudsen and Massih 2000). Detailed nonlinear dynamic behavior of this system is evaluated in our companion paper (Knudsen and Massih 2002b). Computations show that the work-rate for asymmetric orbits is signifi-cantly higher than for symmetric orbits at or near the same frequency. For the vibro-impacting beam, under conditions that exhibit a stable attractor, calculation of work-rate allows us to predict the “lifetime” of the contacting beam due to fretting-wear damage by extending the stable branch and using the local gap between contacting surfaces as a control parameter. That is, upon computation of the impact work-rate, the fretting-wear process time is calculated through back-substitution of the work-rate and gap-width in a given wear law.

Fretting Wear Damage of Heat Exchanger Tubes: A Proposed Damage Criterion Based on Tube Vibration Response

1998 ◽  
Vol 120 (3) ◽  
pp. 297-305 ◽  
Author(s):  
M. Yetisir ◽  
E. McKerrow ◽  
M. J. Pettigrew
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Vibration Frequency ◽  
Vibration Amplitude ◽  
Work Rate ◽  
Nonlinear Finite Element ◽  
Fretting Wear ◽  
Finite Element Program ◽  
Wear Damage ◽  
The Impact

A simple criterion is proposed to estimate fretting wear damage in heat exchanger tubes with clearance supports. The criterion is based on parameters such as vibration frequency, midspan vibration amplitude, span length, tube mass, and an empirical wear coefficient. It is generally accepted that fretting wear damage is proportional to a parameter called work rate. Work rate is a measure of the dynamic interaction between a vibrating tube and its supports. Due to the complexity of the impact-sliding behavior at the clearance supports, work rate calculations for heat exchanger tubes require specialized nonlinear finite element codes. These codes include contact models for various clearance support geometries. Such nonlinear finite element analyses are complex, expensive and time consuming. The proposed criterion uses the results of linear vibration analysis (i.e., vibration frequency and mid-span vibration amplitude due to turbulence) and does not require a nonlinear analysis. It can be used by nonspecialists for a quick evaluation of the expected work rate, and hence, the fretting wear damage of heat exchanger tubes. The proposed criterion was obtained from an extensive parametric study that was conducted using a nonlinear finite element program. It is shown that, by using the proposed work rate criteria, work rate can be estimated within a factor of two. This result, however, requires further testing with more complicated flow patterns.

Experimental Fretting-Wear Studies of Steam Generator Materials

1995 ◽  
Vol 117 (4) ◽  
pp. 312-320 ◽  
Author(s):  
N. J. Fisher ◽  
A. B. Chow ◽  
M. K. Weckwerth
Keyword(s):  
Steam Generator ◽  
Contact Force ◽  
Environmental Conditions ◽  
Analytical Techniques ◽  
Work Rate ◽  
Fretting Wear ◽  
Flow Induced Vibration ◽  
Dynamic Interactions ◽  
Support Materials ◽  
Wear Damage

Flow-induced vibration of steam generator tubes results in fretting-wear damage due to impacting and rubbing of the tubes against their supports. This damage can be predicted by computing tube response to flow-induced excitation forces using analytical techniques, and then relating this response to resultant wear damage using experimentally derived wear coefficients. Fretting-wear of steam generator materials has been studied experimentally at Chalk River Laboratories for two decades. Tests are conducted in machines that simulate steam generator environmental conditions and tube-to-support dynamic interactions. Different tube and support materials, tube-to-support clearances, and tube support geometries have been studied. The effect of environmental conditions, such as temperature, oxygen content, pH and chemistry control additive, have been investigated as well. Early studies showed that damage was related to contact force as long as other parameters, such as geometry and motion, were held constant. Later studies have shown that damage is related to a parameter called work-rate, which combines both contact force and sliding distance. Results of short and long-term fretting-wear tests for CANDU steam generator materials at realistic environmental conditions are presented. These results demonstrate that work-rate is an appropriate correlating parameter for impact-sliding interaction.

Probabilistic Assessment of Fretting Wear in Steam Generator Tubes Under Flow Induced Vibrations

2003 ◽  
Author(s):  
Greg D. Morandin ◽  
Richard G. Sauve´
Keyword(s):  
Steam Generator ◽  
Degradation Mechanism ◽  
Probabilistic Methods ◽  
Fretting Wear ◽  
Nonlinear Flow ◽  
Impact Wear ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
Wear Damage ◽  
The Impact

Successful life management of steam generators requires an ongoing operational assessment plan to monitor and address all potential degradation mechanisms. A degradation mechanism of concern is tube fretting as a result of flow-induced vibration. Flow induced vibration predictive methods routinely used for design purposes are based on deterministic nonlinear structural analysis techniques. In previous work, the authors have proposed the application of probabilistic techniques to better understand and assess the risk associated with operating power generating stations that have aging re-circulating steam generators. Probabilistic methods are better suited to address the variability of the parameters in operating steam generators, e.g., flow regime, support clearances, manufacturing tolerances, tube to support interactions, and material properties. In this work, an application of a Monte Carlo simulation to predict the propensity for fretting wear in an operating re-circulation steam generator is described. Tube wear damage is evaluated under steady-state conditions using two wear damage correlation models based on the tube-to-support impact force time histories and work rates obtained from nonlinear flow induced vibration analyses. Review of the tube motion in the supports and the impact/sliding criterion shows that significant tube damage at the U-bend supports is a result of impact wear. The results of this work provide the upper bound predictions of wear damage in the steam generators. The EPRI wear correlations for sliding wear and impact wear indicate good agreement with the observed damage and, given the preponderance of wear sites subject to impact, should form the basis of future predictions.

Fretting-Wear Damage due to Vibration in Nuclear and Process Equipment

2017 ◽  
Author(s):  
Michel J. Pettigrew ◽  
Metin Yetisir ◽  
Nigel J. Fisher ◽  
Bruce A. W. Smith ◽  
Colette E. Taylor ◽  
...  
Keyword(s):  
Mechanical Energy ◽  
Work Rate ◽  
Point Of View ◽  
Contact Forces ◽  
Fretting Wear ◽  
Process Equipment ◽  
Damage Development ◽  
Simple Formulation ◽  
Piping Systems ◽  
Wear Damage

The problem of fretting-wear damage between a vibrating structure and its supports is discussed in this paper. Typical components of concern are piping systems and pipe-supports, multispan heat exchanger tubes and tube supports, and nuclear fuel bundles and fuel channels. Fretting-wear damage is related to the dynamic interaction between a structure and its supports. This interaction is conveniently formulated in terms of a parameter called “work rate” to predict fretting-wear damage. Work rate is simply the integral of contact force over sliding distance per unit time. Fretting-wear damage may be investigated from an energy point of view. It is essentially the mechanical energy or power dissipated through contact forces and sliding that causes fretting-wear damage. Development of a simple formulation that relates tube vibration response and fretting-wear damage is reviewed in this paper. Some new practical examples and simple calculations are discussed.

A Simple Energy Approach to Assess Vibration and Fretting-Wear Damage in Process Equipment

2007 ◽  
Author(s):  
Michel J. Pettigrew ◽  
Metin Yetisir ◽  
Nigel J. Fisher ◽  
Colette E. Taylor ◽  
Bruce A. W. Smith
Keyword(s):  
Heat Exchanger ◽  
Mechanical Energy ◽  
Work Rate ◽  
Energy Approach ◽  
Fretting Wear ◽  
Process Equipment ◽  
Nuclear Fuels ◽  
Heat Exchanger Tube ◽  
Wear Damage ◽  
Exchanger Tube

Excessive flow-induced vibration causing fretting-wear damage can seriously affect the performance of process equipment such as heat exchangers, condensers, nuclear steam generators, nuclear fuels, reactor internals, and piping systems. Fretting-wear damage generally takes place between a vibrating structure and its supports. It can be predicted with a fretting-wear coefficient obtained experimentally and a parameter called work-rate that formulates the dynamic interaction between structure and support. The work-rate is essentially the rate of mechanical energy dissipated at the support. On the other hand, the total available mechanical vibration energy in a structure is related to its mass, vibration frequency, mode shape, damping, and vibration amplitude. This leads to the development of a simplified formulation based on energy considerations to relate the vibration response of a structure to fretting-wear damage at its supports. The basic energy equations and the formulation of a simplified energy relationship to predict fretting-wear damage are outlined in this paper. The relationship is verified against experimental data for a multi-span heat exchanger tube. The energy approach is also compared to time domain calculations performed with a non-linear finite element code. The results indicate that the simple energy approach may be very useful to estimate fretting-wear damage in practical situations. Finally, the application of the method is illustrated for a typical heat exchanger tube and for nuclear fuels.

The Study of Underfill Epoxy Hardness in Reducing Curing Process Time for Flip Chip Packaging

2011 ◽  
Vol 462-463 ◽  
pp. 1194-1199
Author(s):  
Zainudin Kornain ◽  
Azman Jalar ◽  
Rozaidi Rashid ◽  
Shahrum Abdullah
Keyword(s):  
Thermal Expansion ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Process Time ◽  
Curing Process ◽  
Curing Time ◽  
Hold Temperature ◽  
Flip Chip Packaging ◽  
Time Cycle ◽  
The Impact

Underfilling is the vital process to reduce the impact of the thermal stress that results from the mismatch in the co-efficient of thermal expansion (CTE) between the silicon chip and the substrate in Flip Chip Packaging. This paper reported the pattern of underfill’s hardness during curing process for large die Ceramic Flip Chip Ball Grid Array (FC-CBGA). A commercial amine based underfill epoxy was dispensed into HiCTE FC-CBGA and cured in curing oven under a new method of two-step curing profile. Nano-identation test was employed to investigate the hardness of underfill epoxy during curing steps. The result has shown the almost similar hardness of fillet area and centre of the package after cured which presented uniformity of curing states. The total curing time/cycle in production was potentially reduced due to no significant different of hardness after 60 min and 120 min during the period of second hold temperature.

Time Domain Simulation of the Vibration of a Steam Generator Tube Subjected to Fluidelastic Forces Induced by Two-Phase Cross-Flow

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Téguewindé Sawadogo ◽  
Njuki Mureithi
Keyword(s):  
Steam Generator ◽  
Two Phase Flow ◽  
Work Rate ◽  
Fretting Wear ◽  
Phase Flow ◽  
Reference Case ◽  
Two Phase ◽  
Steam Generator Tube ◽  
Wide Range ◽  
Instability Regime

Having previously verified the quasi-steady model under two-phase flow laboratory conditions, the present work investigates the feasibility of practical application of the model to a prototypical steam generator (SG) tube subjected to a nonuniform two-phase flow. The SG tube vibration response and normal work-rate induced by tube-support interaction are computed for a range of flow conditions. Similar computations are performed using the Connors model as a reference case. In the quasi-steady model, the fluid forces are expressed in terms of the quasi-static drag and lift force coefficients and their derivatives. These forces have been measured in two-phase flow over a wide range of void fractions making it possible to model the effect of void fraction variation along the tube span. A full steam generator tube subjected to a nonuniform two-phase flow was considered in the simulations. The nonuniform flow distribution corresponds to that along a prototypical steam-generator tube based on thermal-hydraulic computations. Computation results show significant and important differences between the Connors model and the two-phase flow based quasi-steady model. While both models predict the occurrence of fluidelastic instability, the predicted pre-instability and post instability behavior is very different in the two models. The Connors model underestimates the flow-induced negative damping in the pre-instability regime and vastly overestimates it in the post instability velocity range. As a result the Connors model is found to underestimate the work-rate used in the fretting wear assessment at normal operating velocities, rendering the model potentially nonconservative under these practically important conditions. Above the critical velocity, this model largely overestimates the work-rate. The quasi-steady model on the other hand predicts a more moderately increasing work-rate with the flow velocity. The work-rates predicted by the model are found to be within the range of experimental results, giving further confidence to the predictive ability of the model. Finally, the two-phase flow based quasi-steady model shows that fluidelastic forces may reduce the effective tube damping in the pre-instability regime, leading to higher than expected work-rates at prototypical operating velocities.

Time Domain Models for Damping-Controlled Fluidelastic Instability Forces in Tubes With Loose Supports

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Marwan Hassan ◽  
Achraf Hossen
Keyword(s):  
Time Domain ◽  
Cross Flow ◽  
Work Rate ◽  
Interaction Parameters ◽  
Similar Response ◽  
Fluid Force ◽  
Support Interaction ◽  
Fluidelastic Instability ◽  
The Impact ◽  
Normal Work

This paper presents simulations of a loosely supported cantilever tube subjected to turbulence and fluidelastic instability forces. Several time domain fluid force models are presented to simulate the damping-controlled fluidelastic instability mechanism in tube arrays. These models include a negative damping model based on the Connors equation, fluid force coefficient-based models (Chen, 1983, “Instability Mechanisms and Stability Criteria of a Group of Cylinders Subjected to Cross-Flow. Part 1: Theory,” Trans. ASME, J. Vib., Acoust., Stress, Reliab. Des., 105, pp. 51–58; Tanaka and Takahara, 1981, “Fluid Elastic Vibration of Tube Array in Cross Flow,” J. Sound Vib., 77, pp. 19–37), and two semi-analytical models (Price and Païdoussis, 1984, “An Improved Mathematical Model for the Stability of Cylinder Rows Subjected to Cross-Flow,” J. Sound Vib., 97(4), pp. 615–640; Lever and Weaver, 1982, “A Theoretical Model for the Fluidelastic Instability in Heat Exchanger Tube Bundles,” ASME J. Pressure Vessel Technol., 104, pp. 104–147). Time domain modeling and implementation challenges for each of these theories were discussed. For each model, the flow velocity and the support clearance were varied. Special attention was paid to the tube/support interaction parameters that affect wear, such as impact forces and normal work rate. As the prediction of the linear threshold varies depending on the model utilized, the nonlinear response also differs. The investigated models exhibit similar response characteristics for the lift response. The greatest differences were seen in the prediction of the drag response, the impact force level, and the normal work rate. Simulation results show that the Connors-based model consistently underestimates the response and the tube/support interaction parameters for the loose support case.

scholarly journals PERCEPTION OF SUSTAINABLE DESIGN INTEGRATION BENEFITS AMONG INDUSTRY PRODUCT DEVELOPMENT TEAMS: A CASE STUDY

2020 ◽  
Vol 1 ◽  
pp. 2475-2484
Author(s):  
T. Chatty ◽  
J. Faludi
Keyword(s):  
Product Development ◽  
Sustainable Design ◽  
Process Time ◽  
Positive Perception ◽  
Development Teams ◽  
Industry Practice ◽  
Design Integration ◽  
The Impact ◽  
Development Practice

AbstractHow do employees perceive the impact of incorporating sustainability considerations into their product development practice? In this case study, we observe how these perceptions can be shifted by teaching workshops on how to apply sustainable design methods in practice. We compare the trends for different methods on various dimensions such as creativity, design process time, product marketability etc. Results show an overall shift towards positive perception for all the methods on a majority of factors, indicating a way to ease the adoption of sustainable design into industry practice.

Assessment of Fretting‐Wear Damage in Nuclear and Process Equipment

2021 ◽  
pp. 373-395
Author(s):  
Michel J. Pettigrew ◽  
Metin Yetisir ◽  
Nigel J. Fisher ◽  
Bruce A. W. Smith ◽  
Victor P. Janzen
Keyword(s):  
Fretting Wear ◽  
Process Equipment ◽  
Wear Damage
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