Elastodynamic Inversion of Multilayered Media via Surface Waves—Part II: Implementation and Numerical Verification

2011 ◽  
Vol 78 (4) ◽  
Author(s):  
Feiquan Luo ◽  
Lu Sun ◽  
Wenjun Gu
Keyword(s):  
Computer Program ◽  
Dynamic Analysis ◽  
Numerical Algorithms ◽  
Numerical Verification ◽  
Falling Weight Deflectometer ◽  
Multilayered Media ◽  
Estimated Parameters ◽  
Multilayered Medium ◽  
Analysis Computer ◽  
Falling Weight

An effective inverse analysis computer program that integrates nonlinear optimization algorithm and forward dynamic analysis of multilayered medium is developed for inferring structural and material properties (e.g., modulus, thickness, and the number of layers) of the medium. Using dynamic deflection information obtained from forward dynamic analysis of the multilayered medium as a hypothetical deflection measured from the field during pavement nondestructive evaluation (NDE) using falling weight deflectometer, the estimated parameters of the medium are compared with the known true parameters of the medium used to perform the static and forward dynamic analyses. Based on two different multilayered media, a number of important observations and conclusions are made regarding the accuracy and efficiency of the proposed numerical algorithms and developed computer program. The inversion methods presented in this paper show improved NDE results over many of the existing algorithms.

Dynamic simulation of falling weight deflectometer tests on flexible pavements using the spectral element method: forward calculations

2009 ◽  
Vol 36 (6) ◽  
pp. 944-956 ◽  
Author(s):  
Simon Grenier ◽  
Jean-Marie Konrad ◽  
Denis LeBœuf
Keyword(s):  
Dynamic Analysis ◽  
Spectral Element Method ◽  
Flexible Pavements ◽  
Computer Code ◽  
Spectral Element ◽  
Falling Weight Deflectometer ◽  
Viscous Effects ◽  
Damping Material ◽  
Falling Weight ◽  
Element Method

A dynamic analysis based on the spectral element method is described for the interpretation of falling weight deflectometer (FWD) tests on flexible pavements. This dynamic approach was implemented in the computer code Dynamic Analysis of Pavement - Université Laval (DYNAPAV-UL) that includes both frequency-independent hysteretic damping and frequency-dependent viscous damping material models. A parametric study was conducted on a four-layer flexible pavement to evaluate the influence of different layer moduli on deflection basins and deflection histories. The viscous behaviour of the asphalt concrete layer was also investigated. While the deflection basin currently used in static methods gives some details of the pavement response under transient loading, the simulations of FWD tests using the dynamic model suggest that the time histories should be included as well for the interpretation of FWD deflection measurements. In fact, important dynamic phenomena due to inertial effects and viscous effects are only revealed by deflection histories.

The Analysis and Design of a Fire Engine Safety Cab Using Finite Element Methods

1977 ◽  
Vol 191 (1) ◽  
pp. 187-193 ◽  
Author(s):  
J. C. Miles ◽  
G. A. Wardill
Keyword(s):  
Finite Element ◽  
Computer Program ◽  
Three Dimensional ◽  
Analysis And Design ◽  
Vehicle Structure ◽  
Collapse Analysis ◽  
Incremental Formulation ◽  
Analysis Computer ◽  
Fire Engine ◽  
Analysis Computer Program

A three dimensional structural collapse analysis computer program is described, and illustrated by reference to a safety vehicle structure analysed and designed using the program. The particular problems of large displacements and material non-linearity are accounted for, and a method of estimating the permanent set which results after impact is described. Based on an incremental formulation of the conventional finite-element method, the computer program is capable of tracing the complete load deflection characteristics of a structure up to and beyond the point of collapse.

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