The paper presents the main ride problems found in passenger-car suspensions and numerical data illustrating present practice. Analyses of transient conditions are shown: ( a ) for a single sprung mass, ( b ) for the car as a system with two degrees of freedom, ( c ) for the effect of the seat cushion. The motions of the unsprung masses between road surface and chassis are defined as shake motions. Data are given for the vertical motion “wheelhop.” As an example of secondary shakes, the sideshake of an axle is described from test data.

Scavenging mechanical energy from the deformation of roadways using piezoelectric energy transformers has been intensively explored and exhibits a promising potential for engineering applications. We propose here a new packaging method that exploits MC nylon and epoxy resin as the main protective materials for the piezoelectric energy harvesting (PEH) device. Wheel tracking tests are performed, and an electromechanical model is developed to double evaluate the efficiency of the PEH device. Results indicate that reducing the embedded depth of the piezoelectric chips may enhance the output power of the PEH device. A simple scaling law is established to show that the normalized output power of the energy harvesting system relies on two combined parameters, i.e., the normalized electrical resistive load and normalized embedded depth. It suggests that the output power of the system may be maximized by properly selecting the geometrical, material, and circuit parameters in a combined manner. This strategy might also provide a useful guideline for optimization of piezoelectric energy harvesting system in practical roadway applications.

Highways consume enormous electric power and therefore contribute to heavy economic costs due to the operation of auxiliary road facilities including lighting, displays, and health-monitoring systems for tunnels and bridges, etc. We here propose a new strategy of electric power supply for highways by harvesting mechanical energy from the reciprocating deformation of road pavements. A series of wheel tracking tests are performed to demonstrate the possibility of using piezoelectric elements to transform the mechanical energy stored in pavements due to vehicular load into electricity. An analytical electromechanical model is developed to predict the correlations between electric outputs and loading conditions in the wheel tracking test. A simple scaling law is derived to show that the normalized output power depends on the normalized loading period, location, and size of the piezoelectric device. The scaling law is further extended to a practical highway application according to the analogy between the wheel tracking test and a highway in an idealized condition of periodic vehicular load. It suggests that the output power may be maximized by tuning the material and geometry of the piezoelectric device under various conditions of speed limit and vehicle spacing. The present results may provide a useful guideline for designing mechanical energy-harvesting systems in various road pavements.

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.

A rigorous theoretical foundation for solving elastodynamic inverse problem of multilayered media under an impulse load is established in this paper. The inversion is built upon the forward dynamic analysis of multilayered elastic media using transfer matrix approach, with which displacement continuity is assumed at the interfaces of upper and lower adjacent layers. Formulations for inverse analysis are derived in both the time domain and the complex frequency domain. Least square estimates and nonlinear optimization algorithms are used to implement parameter identification. The proposed theory and formulae can be utilized to develop a computer software for nondestructive evaluation of laminated civil and aerospace structure (highway and airport pavements, bridge decks, soil foundations, aircraft wing, etc.), exploration and dynamic source detection and identification, and petroleum exploration in geophysics.

The purpose of this paper is to study the dynamics of the accelerating bicycle. It is shown that time-scale separation can be used to study the oscillatory characteristics of the accelerating machine using time-invariant models. These models are used to explain practically observed wobble-mode bursting oscillations that are associated most frequently with down-hill riding. If the vehicle is cornering under constant acceleration, at a fixed roll angle, it is shown that for low values of acceleration (and braking), it follows closely a logarithmic spiral shaped trajectory. The studies presented are facilitated by a novel adaptive control scheme that centers the machine’s trajectory on any arbitrary point in the ground plane. The influences of cambered road surfaces are also investigated. The bicycle model employed is an extension of that originally developed by Whipple, and comprises two road wheels and two laterally-symmetric frame assemblies that are free to rotate relative to each other along an inclined steering axis. For the most part, the front frame is treated as being flexible and the bicycle is fitted with force generating road tires, rather than classical nonholonomic rolling constraints. This research provides the ground work required for generating more complex dynamic models for high-performance motorcycle studies.

In this paper Fourier transform is used to derive the analytical solution of a Kirchhoff plate on a viscoelastic foundation subjected to harmonic circular loads. The solution is first given as a convolution of the Green’s function of the plate. Poles of the integrand in the integral representation of the solution are identified for different cases of the foundation damping and the load frequency. The theorem of residue is then utilized to evaluate the generalized integral of the frequency response function. A closed-form solution is obtained in terms of the Bessel and Hankel functions corresponding to the frequency response function of the plate under a harmonic circular load. The result is partially verified by comparing the static solution of a point source obtained in this paper to a well-known result. This analytical representation permits one to construct fast algorithms for parameter identification in pavement nondestructive test.

In this paper, the analytic solution for simulating the thermal stress field in a bituminous pavement is put forward based on a two-dimensional thermoviscoelastic layered system. The numerical analysis is made for the thermal stress field under the typical weather conditions in the north of China. Some new results are obtained. A discussion on the optimum thickness design for the bituminous pavement is given in the final section.

This paper is concerned with the problem of dynamic instability during ice-lifting from a flat surface through penetration of the interface by means of a sharp blade. The blade is subjected to a horizontal impulsive load and a constant horizontal thrust, both applied suddenly and simultaneously. The principle of the balance of energy is used to analyze the deformation of the ice associated with the crack propagation along the interface. In our formulation, the effect of wave propagation in the ice is neglected. However, the inertia force due to the acceleration of the blade is included. The motion of the blade is investigated by the numerical solution of a complex, nonlinear, initial value problem. It is found that under a given horizontal thrust, if the initial velocity of the blade is sufficiently small, the motion of the blade may stop. However, if the initial velocity of the blade is sufficiently large, the motion of the blade is always forward and the crack can propagate indefinitely along the interface.