Pavement displacement sensitivity to layer moduli

2002 ◽  
Vol 39 (6) ◽  
pp. 1395-1398
Author(s):  
Dieter Stolle
Keyword(s):  
Finite Element ◽  
Surface Displacement ◽  
Falling Weight Deflectometer ◽  
Contribution Ratio ◽  
Displacement Sensitivity ◽  
Stiffness Characteristics ◽  
Element Technique ◽  
Falling Weight ◽  
The Relationship ◽  
Displacement Measurements

The backcalculation of layer moduli using falling weight deflectometer data has proven to be challenging owing to the insensitivity of displacement measurements to the stiffness characteristics of some layers. This note describes a rigorous, yet simple, finite element technique for identifying the relationship between surface displacement and the elastic modulus of each layer. An example is given to demonstrate the application of the procedure.Key words: pavements, subgrade, backcalculation, contribution ratio.

Interpretation of pavement deflection measurement data using an elastodynamic stochastic approach

1998 ◽  
Vol 25 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Mehdi Parvini ◽  
Dieter FE Stolle
Keyword(s):  
Finite Element ◽  
Measurement Data ◽  
Stochastic Approach ◽  
Falling Weight Deflectometer ◽  
Stochastic Finite Element ◽  
Element Approach ◽  
Subgrade Modulus ◽  
Low Sensitivity ◽  
Falling Weight ◽  
Surface Deflections

Pavement deflection measurements, together with backcalculation procedures, are widely used to estimate the layer moduli of pavement-subgrade systems. Sensitivity analysis of a sample problem indicates that conclusions drawn from static analyses with regards to deflection sensitivity to variation in layer moduli may apply when characterizing uncertainty associated with the interpretation of the falling weight deflectometer (FWD) data. The uncertainty associated with the values of the backcalculated parameters from deflection data is investigated in this paper using an elastodynamic, stochastic finite element approach. The results of the simulations indicate that, in order to properly estimate surface layer moduli, loading frequencies higher than that of excitation by typical FWD loading are required. The low sensitivity of deflection uncertainty to random variations in surface modulus, when compared with that associated with subgrade modulus, is demonstrated to contribute to high variations in backcalculated surface modulus from measured surface deflections. Although focus is placed on uncertainties in elastic modulus and deflection, the methodology presented in the paper can be used to quantify uncertainties associated with other layer properties and pavement responses.Key words: stochastic, finite element, pavement deflection, elastodynamic, backcalculation, layer moduli, falling weight deflectometer test.

scholarly journals Relationship between deformation moduli obtained using light falling weight deflectometer and static plate test on various types of soil

2014 ◽  
Vol 9 (4) ◽  
pp. 251-259 ◽  
Author(s):  
Karel Pospisil ◽  
Petr Zednik ◽  
Josef Stryk
Keyword(s):  
Test Methods ◽  
Falling Weight Deflectometer ◽  
Loading Test ◽  
Plate Test ◽  
Plate Loading Test ◽  
Static Modulus ◽  
Different Types ◽  
Falling Weight ◽  
The Relationship ◽  
Plate Loading

There is increasing effort to optimize test methods for evaluation of subgrade. It takes effect in aspiration in replacement of static plate loading test by other faster test methods. One of them is the use of Light Falling Weight Deflectometer. In many countries in Europe both static and dynamic plate tests are standardized. The presented paper introduces results of the research project dealing with the sensitivity of the relationship between static modulus and modulus obtained from the Light Falling Weight Deflectometer on specific types of soil. It is shown that there are significant differences in relationship between moduli values obtained using both methods on different types of soil.

Correlation of Non-Destructive Pavement Test Devices

2014 ◽  
Vol 912-914 ◽  
pp. 613-616
Author(s):  
Sheng Chun Li
Keyword(s):  
Field Measurements ◽  
Falling Weight Deflectometer ◽  
Pavement Rehabilitation ◽  
Ningxia Hui Autonomous Region ◽  
Aashto 1993 ◽  
Falling Weight ◽  
Near Future ◽  
The Relationship ◽  
Non Destructive ◽  
Rehabilitation Strategy

This paper studies the correlation of non-destructive pavement test devices, the falling weight deflectometer (FWD) and Benkelman Beam (BB), in evaluation of pavement structure capacity. Field measurements were made at an expansion highwayG6 in Ningxia Hui Autonomous Region, China. Based on the deflection results measured with FWD and BB, the relationship between FWD and BB was established. The subgrade moduli of the test section were back-calculated. The results show that the ratio of E(sta) and MR(dyn) is consistent with the suggestion of AASHTO 1993. Due to the fact that the use of FWD test is convenient and the results are stable, it demonstrates that the falling weight deflectometer (FWD) is an appropriate device to evaluate the pavement structural and to select the optimal pavement rehabilitation strategy in the near future.

The Plastic Ratcheting of Thin Cylindrical Shells Subjected to Axisymmetric Thermal and Mechanical Loading

1987 ◽  
Vol 109 (4) ◽  
pp. 387-393 ◽  
Author(s):  
S. Karadeniz ◽  
A. R. S. Ponter ◽  
K. F. Carter
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Mechanical Loading ◽  
Material Properties ◽  
Thermal Loading ◽  
Cylindrical Shells ◽  
Temperature Fields ◽  
Mechanical Loads ◽  
Element Technique ◽  
The Relationship

The paper discusses the relationship between material properties and structural ratcheting for thin cylindrical shells subjected to severe thermal loading. The need to understand this problem arises in the design of Sodium Cooled Fast Reactors. A sequence of shakedown solutions are presented using a finite element technique [13]. It is shown that for tubes subject to moving temperature fields, ratcheting can occur even when no mechanical loads are applied and the material strongly cyclically hardens. Only small movements are required. Stationary thermal cycling is less likely to produce ratcheting. The calculations are compared with two sets of experimental data, which serve to confirm these conclusions.

Research on the Identification Method for Void Location of Semi-Rigid Base Pavement

2011 ◽  
Vol 94-96 ◽  
pp. 1257-1260
Author(s):  
Yan Hui Zhong ◽  
Bei Zhang ◽  
Cheng Chao Guo ◽  
Jin Qi
Keyword(s):  
Finite Element ◽  
Field Test ◽  
Critical Value ◽  
Rigid Base ◽  
Falling Weight Deflectometer ◽  
Analysis Model ◽  
Finite Element Software ◽  
Identification Method ◽  
Falling Weight

Using finite element software, the analysis model of semi-rigid base pavement with voids is established. Variation of deflection under load of Falling Weight Deflectometer (FWD) is studied and the reference critical value is obtained to determine whether there are the voids. According to analysis of the deflection basin data under different location, the identification method for the void location of semi-rigid base pavement is established. The field test shows that it is feasible to use this technology in void identification for semi-rigid base pavement.

Dynamic Interpretation of Falling Weight Deflectometer Test Results: Spectral Element Method

2000 ◽  
Vol 1716 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Rafid AI-Khoury ◽  
Athanassios Scarpas ◽  
Cor Kasbergen ◽  
Johan Blaauwendraad
Keyword(s):  
Iterative Algorithms ◽  
Spectral Element ◽  
Falling Weight Deflectometer ◽  
Reflection And Refraction ◽  
Element Program ◽  
Pavement Structure ◽  
Element Technique ◽  
Falling Weight ◽  
Impact Of Falling ◽  
Element Method

The use of spectral analysis as a means of analyzing the dynamic impact of falling weight deflectometer (FWD) load pulses on pavements is covered. The spectral element technique is utilized. Only forward analyses of pavement dynamics are presented, with the emphasis on the suitability of the method for solving inverse problems. LAMDA (layered media dynamic analysis), a newly developed spectral element program, is utilized for the simulation of the interaction between the FWD load pulse and the pavement structure. In LAMDA, the formulation of the wave propagation, reflection, and refraction in a layer is done in a closed form. The assembling of the elements (in the multilayer system) is carried out in a manner similar to that in the finite element method. Consequently, the size of the mesh of a pavement structure is as large as the number of the layers involved. This reduces the computational requirements substantially and hence enables utilization of LAMDA in iterative algorithms for backcalculation purposes.

Application of holographic interferometry to cylinder deformation

1987 ◽  
Vol 22 (2) ◽  
pp. 63-74 ◽  
Author(s):  
W T Evans ◽  
R M Russell ◽  
A White
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Holographic Interferometry ◽  
Surface Displacement ◽  
Field Of View ◽  
Surface Point ◽  
Temperature Distributions ◽  
Detailed Surface ◽  
Analysis Package ◽  
Displacement Measurements

Detailed surface displacement measurements have been made on the surface of a thermally deformed cylinder using a real-time holographic interferometry technique to measure the cartesian components of surface displacement at any surface point in the field of view. No assumptions were made as to the type and direction of displacements being measured and the resulting equations were analysed using a computer analysis package (I)† developed at the Polytechnic of Wales. For comparative purposes, elastic finite-element programs working on experimental temperature distributions were used in a theoretical model of the experiments.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

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