A continuum damage mechanics (CDM) meso-model was derived for both intraply and interply progressive failure behaviors of a 2D woven-fabric composite laminate under a transversely low velocity impact. An in-plane anisotropic damage constitutive model of a 2D woven composite ply was derived based on CDM within a thermodynamic framework, an elastic constitutive model with damage for the fibre directions and an elastic-plastic constitutive model with damage for the shear direction. The progressive failure behavior of a 2D woven composite ply is determined by the damage internal variables in different directions with appropriate damage evolution equations. The interface between two adjacent 2D woven composite plies with different ply orientations was modeled by a traction-separation law based interface element. An isotropic damage constitutive law with CDM properties was used for the interface element, and a damage surface which combines stress and fracture mechanics failure criteria was employed to derive the damage initiation and evolution for the mixed-mode delamination of the interface elements. Numerical analysis and experiments were both carried out on a 2D woven glass fibre/epoxy laminate. The simulation results are in agreement with the experimental counterparts, verifying the progressive failure model of a woven composite laminate. The proposed model will enhance the understanding of dynamic deformation and progressive failure behavior of composite laminate structures in the low velocity impact process.

Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses, flux leakage or saturation of iron. In this paper, based on results from an experimental set-up designed to study magnetic force, a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients. The parameters of the proposed model are identified using the weighted residual method. Validations of the model identified were performed by comparing the results in time and frequency domains. The results show a good correlation between experiments and numerical simulations.

A coal slurry mixing tank is a key piece of equipment in the preparation of coal slurry for direct coal liquefaction. It is a gas-liquid-solid three-phase mixing device. Based on the performance of the existing coal slurry mixing equipment, a type of test equipment for horizontal continuous coal slurry preparation was developed, but to this point has limited research results. The test equipment consists of a mixing cylinder, mixer, stirring impeller and other components. Slurry mixing experiments were undertaken using the prototype, testing the performance of the device. A mathematical model was proposed specifically for the operation of a coal slurry mixing tank that is horizontally operated with high slurry concentration and rotary flow. The flow field in the horizontal coal mixing tank was simulated with the computational fluid dynamic (CFD) method. The experimental results match well with the CFD simulation results. Results show that the test device of a coal slurry mixing tank can be used to model the mixing of pulverized coal and the solvent oil. A strong correlation was obtained.

The single cylinder and multi-cylinder pumping dynamics model of a swash plate piston pump were improved. Particular attention has been paid to the design influences of key parts of the valve plate such as relief groove, pre-compression/ expansion and fluid inertia effect of the unsteady flow. Some important parameters, such as the discharge area, discharge coefficient, fluid bulk modulus, were especially analyzed using numerical methods or by experiment-based estimation. Consequently, the mathematical results of pressure pulsation and flow ripple agree well with experimental results from the test-rig of the flow ripple. Therefore, the cross angle and the pre-compression angle of the valve plate was optimized, based on the pumping dynamics model. Considering both the flow ripple and the cylinder pressure of the pump, the cross angle is set to be 2.2° to 2.7° with a pre-compression angle of 1.7° to 2.2°, so the pumping dynamics character can obtain the best result.

For automated vehicles, comfortable driving will improve passengers’ satisfaction. Reducing fuel consumption brings economic profits for car owners, decreases the impact on the environment and increases energy sustainability. In addition to comfort and fuel-economy, automated vehicles also have the basic requirements of safety and car-following. For this purpose, an adaptive cruise control (ACC) algorithm with multi-objectives is proposed based on a model predictive control (MPC) framework. In the proposed ACC algorithm, safety is guaranteed by constraining the inter-distance within a safe range; the requirements of comfort and car-following are considered to be the performance criteria and some optimal reference trajectories are introduced to increase fuel-economy. The performances of the proposed ACC algorithm are simulated and analyzed in five representative traffic scenarios and multiple experiments. The results show that not only are safety and car-following objectives satisfied, but also driving comfort and fuel-economy are improved significantly.

Two experimental tests of three-storied reinforced concrete structural walls having large openings were performed. Based on an original macro model, a multiple modified macro-model was proposed to develop a simple method to design a reinforced concrete structural wall with large openings and various opening locations. The interaction between reinforcement ties and concrete struts formed along the perimeter of openings was neglected in the original model. However, the strut-and-tie node was proposed to take account of such interaction in the proposed model. The predicted behavior of two specimens using such a proposed model was compared with the experimental results. It is shown that the behavior of structural walls with large openings could be modeled well using the proposed model. Moreover, the study indicates that the proposed model is applicable even in cases of multi-story structural walls having large openings and various opening locations.

This study explored the potential of using probabilistic neural networks (PNN) to predict shrinkage of thermal insulation mortar. Probabilistic results were obtained from the PNN model with the aid of Parzen non-parametric estimator of the probability density functions (PDF). Five variables, water-cementitious materials ratio, content of cement, fly ash, aggregate and plasticizer, were employed for input variables, while a category of 56-d shrinkage of mortar was used for the output variable. A total of 192 groups of experimental data from 64 mixtures designed using JMP7.0 software were collected, of which 120 groups of data were used for training the model and the other 72 groups of data for testing. The simulation results showed that the PNN model with an optimal smoothing parameter determined by the curves of the mean square error (MSE) and the number of unrecognized probability densities (UPDs) exhibited a promising capability of predicting shrinkage of mortar.

Top-down crack in asphalt pavements has been reported as a widespread mode of failure. A solid understanding of the mechanisms of crack growth is essential to predict pavement performance in the context of thickness design, as well as in the design and optimization of mixtures. Using the coupled element free Galerkin (EFG) and finite element (FE) method, top-down crack propagation in asphalt pavements is numerically simulated on the basis of fracture mechanics. A parametric study is conducted to isolate the effects of overlay thickness and stiffness, base thickness and stiffness on top-down crack propagation in asphalt pavements. The results show that longitudinal wheel loads are disadvantageous to top-down crack because it increases the compound stress intensity factor (SIF) at the tip of top-down crack and shortens the crack path, and thus the fatigue life descends. The SIF experiences a process “sharply ascending—slowly descending—slowly ascending—sharply ascending again” with the crack propagating. The thicker the overlay or the base, the lower the SIF; the greater the overlay stiffness, the higher the SIF. The crack path is hardly affected by stiffness of the overlay and base.