scholarly journals Comparison of Mechanical Impedance Methods for Vibration Simulation

1996 ◽  
Vol 3 (3) ◽  
pp. 223-232 ◽  
Author(s):  
Jeffrey A. Gatscher ◽  
Grzegorz Kawiecki
Keyword(s):  
Mechanical Impedance ◽  
Field Measurements ◽  
Cumulative Damage ◽  
Vibration Test ◽  
Element Analysis ◽  
Impedance Measurements ◽  
Testing Strategies ◽  
Impedance Testing ◽  
Vibration Simulation ◽  
Test Requirements

The work presented here explored the detrimental consequences that resulted when mechanical impedance effects were not considered in relating vibration test requirements with field measurements. The ways in which these effects can be considered were evaluated, and comparison of three impedance methods was accomplished based on a cumulative damage criterion. A test structure was used to simulate an equipment and support foundation system. Detailed finite element analysis was performed to aid in computation of cumulative damage totals. The results indicate that mechanical impedance methods can be effectively used to reproduce the field vibration environment in a laboratory test. The establishment of validated computer models, coupled with laboratory impedance measurements, can eliminate the overtesting problems inherent with constant motion, infinite impedance testing strategies.

Finite element analysis of a vibration test bed frame

2017 ◽  
Vol 59 (2) ◽  
pp. 183-187 ◽  
Author(s):  
Dong Lei ◽  
Rui Jiang ◽  
Pengxiang Bai ◽  
Feipeng Zhu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Vibration Test ◽  
Test Bed ◽  
Element Analysis

Dynamic Characterization of an Integral Squeeze Film Bearing Support Damper for a Supercritical CO2 Expander

2017 ◽  
Author(s):  
Bugra Ertas ◽  
Adolfo Delgado ◽  
Jeffrey Moore
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Mechanical Impedance ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Damping Behavior ◽  
Impedance Testing ◽  
Stiffness And Damping ◽  
Onset Of Cavitation

The present work advances experimental results and analytical predictions on the dynamic performance of an integral squeeze film damper (ISFD) for application in a high-speed super-critical CO2 (sCO2) expander. The test campaign focused on conducting controlled orbital motion mechanical impedance testing aimed at extracting stiffness and damping coefficients for varying end seal clearances, excitation frequencies, and vibration amplitudes. In addition to the measurement of stiffness and damping; the testing revealed the onset of cavitation for the ISFD. Results show damping behavior that is constant with vibratory velocity for each end seal clearance case until the onset of cavitation/air ingestion, while the direct stiffness measurement was shown to be linear. Measurable added inertia coefficients were also identified. The predictive model uses an isothermal finite element method to solve for dynamic pressures for an incompressible fluid using a modified Reynolds equation accounting for fluid inertia effects. The predictions revealed good correlation for experimentally measured direct damping, but resulted in grossly overpredicted inertia coefficients when compared to experiments.

Field measurements in two tunnels in Edmonton, Alberta

1980 ◽  
Vol 17 (1) ◽  
pp. 20-33 ◽  
Author(s):  
S. Thomson ◽  
F. El-Nahhas
Keyword(s):  
Body Movement ◽  
Small Diameter ◽  
Ground Surface ◽  
Beam Theory ◽  
Field Measurements ◽  
Element Analysis ◽  
Overburden Pressure ◽  
Pressure Cell ◽  
Horizontal Diameter ◽  
Overburden Thickness

Observations of the deformation of the temporary lining of two tunnels are presented. The Whitemud Creek tunnel was 6.05 m in diameter and was bored through Upper Cretaceous clay shale. The 170 Street tunnel was bored through till and had a diameter of 2.56 m.In the Whitemud Creek tunnel, the vertical diameter decreased by 10–15 mm and the horizontal diameter decreased by 6 mm. Movement was essentially complete in about 3 months. There was a rigid body movement upward of the lining system probably due to unloading of the soil in the invert area. Deformation moduli indicate a softening of the soil around the tunnel, which is consistent with the deformation observations. A finite-element analysis suggests that this softened zone is as important with regard to lining deformation as increasing K0 from 0.67 to 1.0In the 170 Street tunnel, the ground surface showed significant movement despite the small diameter and considerable overburden thickness. The vertical and horizontal diameter decreases were about one half of those of the Whitemud Creek tunnel and were essentially complete in 4–5 weeks. Soil pressures calculated from the observations showed a wide variation. Values derived from lagging deflection yielded a maximum of 63% of overburden pressure whereas pressure cell readings were 3.3% of overburden.It appears that the space between the lagging and the moled surface of the soil is an important factor affecting the magnitude of stresses in the temporary lining. Diameter changes are considered to be the easiest and most reliable observation of tunnel linings. The deflection of the lagging is also simple to observe but may not satisfy simple beam theory. Pressure cell results were disappointing and their use is debatable.

Using the Asphalt Pavement Layer Condition Assessment Program: Case Studies

2003 ◽  
Vol 1860 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Bing Xu ◽  
S. Ranji Ranjithan ◽  
Y. Richard Kim
Keyword(s):  
Case Studies ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Dynamic Effect ◽  
Field Measurements ◽  
Condition Assessment ◽  
Base Layer ◽  
Element Analysis ◽  
Condition Indicators ◽  
Assessment Program

The Asphalt Pavement Layer Condition Assessment Program (APLCAP) is developed in this research to help highway agencies assess layer conditions of asphalt pavements. APLCAP implements a new integrated procedure for condition assessment from falling-weight deflectometer (FWD) deflections. The main components of this procedure include screening of FWD raw deflections, predictions of condition indicators from FWD measurements, structural adjustments for the predicted condition indicators, and layer condition evaluation based on the adjusted condition indicators. This procedure was developed on the basis of dynamic nonlinear finite element analysis and calibrated using field measurements. The three case studies presented show that the APLCAP algorithms can predict the asphalt concrete modulus, pavement critical strains, and strengths of the base and subgrade quite well, but not the compressive strain in the aggregate base layer. Although the APLCAP procedure includes the complicated dynamic effect of FWD loading and nonlinear behavior of unbound materials, the time to obtain results from this procedure is insignificant and therefore suitable for real-time evaluation of pavement conditions.

Evaluating the Effects of Ovality on the Integrity of Pipe Bends

2012 ◽  
Author(s):  
Chris Alexander
Keyword(s):  
Field Measurements ◽  
Element Analysis ◽  
Rigorous Evaluation ◽  
Pipe System ◽  
Extensive Evaluation ◽  
Assessment Approach ◽  
Level 3 ◽  
Multi Level ◽  
Engineering Investigation ◽  
Level 2

This paper provides details on a study performed for a liquids pipeline operator to evaluate the effects of ovality on the mechanical integrity of pipe bends in their 16-inch pipe system. Prior to this study, a caliper tool was run that indicated unacceptable ovality was present in the bends relative to the requirements set forth in ASME B31.4. An engineering investigation was performed based on the methodology of API 579 Fitness for Service. This standard provides guidance on evaluating defects using a multi-level assessment approach (Levels 1, 2, and 3) that rewards rigorous evaluation efforts by reducing the required design margins. Therefore, an extensive evaluation was performed that involved making field measurements of the bends in the ditch. Using these ovality measurements, calculations were performed using the closed-form equations in API 579 for Level 2 assessment. The ovality of several of the bends in the field was deemed unacceptable based on in-field measurements. Consequently, a Level 3 assessment was completed using finite element analysis (FEA). The results of this more rigorous analysis, coupled with more favorable design margins, resulted in this particular bend being acceptable. A tool was developed to permit a general assessment of pipe bends having ovality and was validated by performing a full-scale burst test.

Flatwise Young’s modulus and flatwise shear modulus of plywood measured by flexural vibration test

Holzforschung ◽  
2013 ◽  
Vol 67 (6) ◽  
pp. 683-690 ◽  
Author(s):  
Hiroshi Yoshihara
Keyword(s):  
Finite Element Analysis ◽  
Shear Modulus ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Flexural Vibration ◽  
Vibration Test ◽  
Specimen Length ◽  
Element Analysis ◽  
Flexural Vibration Test ◽  
Vibration Tests

Abstract The flatwise Young’s modulus and the flatwise shear modulus of 3-, 5-, and 7-ply plywoods made of Lauan (Shorea sp.) veneers have been determined by conducting flexural vibration tests with various specimen lengths and by finite element analysis. The results indicate that the flatwise Young’s modulus decreases with decreasing specimen length, whereas the opposite is true for the flatwise shear modulus.

scholarly journals Experiment and finite element analysis of U-profile subjected to dynamic loading

2018 ◽  
Vol 183 ◽  
pp. 02056
Author(s):  
Martin Rund ◽  
Martin Mašek ◽  
Jan Džugan ◽  
Pavel Konopík ◽  
Jiøí Janovec
Keyword(s):  
Dynamic Loading ◽  
Fem Simulation ◽  
Field Measurements ◽  
Material Model ◽  
Tensile Tests ◽  
Ductile Damage ◽  
Experimental Investigations ◽  
Loading Conditions ◽  
Element Analysis ◽  
Dynamic Loading Conditions

The presented study deals with the FEM simulation of dynamic behaviour of U-profile crash under three point bent loading conditions verified by experimental investigations. The material ductile damage behaviour under wide strain rate region covering 0.001 – 1 000 s-1 was experimentally determined with the use of standard and micro tensile tests (M-TT). DIC systems were used for strain field measurements under quasi-static and dynamic loading conditions. Based on these experimental data, material model considering ductile damage was established in Abaqus/Explicit code. Additionally, also metallographic investigations were performed for the fracture behaviour description.

scholarly journals Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure

2020 ◽  
Vol 8 (5) ◽  
pp. 358 ◽  
Author(s):  
Yusak Oktavianus ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Gideon Kusuma ◽  
Colin Duffield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Field Measurement ◽  
Field Measurements ◽  
Element Analysis ◽  
Moment Capacity ◽  
Non Destructive

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.

Calculated and observed behaviour of a reinforced embankment over soft compressible soil

1996 ◽  
Vol 33 (2) ◽  
pp. 324-338 ◽  
Author(s):  
R Kerry Rowe ◽  
C T Gnanendran ◽  
A O Landva ◽  
A J Valsangkar
Keyword(s):  
Progressive Failure ◽  
Large Strain ◽  
Field Measurements ◽  
Clay Material ◽  
Element Analysis ◽  
Foundation Soil ◽  
Clayey Silt ◽  
Modified Cam Clay ◽  
Compressible Soil ◽  
Cam Clay

The finite element analysis of an instrumented geotextile-reinforced test embankment is described and the results are compared with the field measurements. The embankment was constructed to failure on a soft compressible organic clayey silt deposit at Sackville, New Brunswick. The analysis adopts a fully coupled large-strain elasto-plastic Biot consolidation model with modified Cam-clay material behaviour. It is shown that the analysis captured many features of the embankment behaviour. However, it is concluded that the elasto-plastic modified Cam-clay formulation is not adequate for accurately and simultaneously predicting the multiple characteristics (e.g., vertical and horizontal deformations, pore pressures, and geotextile strains) of the embankment behaviour, primarily because of the rate sensitive nature, and the consequent progressive failure of the foundation soil. Key words: embankment, geotextile, reinforcement, analysis, field behaviour, deformations.

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