Enhanced asphalt dynamic modulus prediction: A detailed analysis of artificial hummingbird algorithm-optimised boosted trees

This study introduces and evaluates a novel artificial hummingbird algorithm-optimised boosted tree(AHAboosted)model for predicting the dynamic modulus(E*)of hot mix asphalt concrete.Using a substantial dataset from NCHRP Report-547,the model was trained and rigorously tested.Performance metrics,specifically RMSE,MAE,and R2,were employed to assess the model's predictive accuracy,robustness,and generalisability.When benchmarked against well-established models like support vector machines(SVM)and gaussian process regression(GPR),the AHA-boosted model demonstrated enhanced performance.It achieved R2 values of 0.997 in training and 0.974 in testing,using the traditional Witczak NCHRP 1-40D model inputs.Incorporating features such as test temperature,frequency,and asphalt content led to a 1.23%increase in the test R2,signifying an improvement in the model's accuracy.The study also explored feature importance and sensitivity through SHAP and permutation importance plots,highlighting binder complex modulus|G*|as a key predictor.Although the AHA-boosted model shows promise,a slight decrease in R2 from training to testing indicates a need for further validation.Overall,this study confirms the AHA-boosted model as a highly accurate and robust tool for predicting the dynamic modulus of hot mix asphalt concrete,making it a valuable asset for pavement engineering.

Dynamic shear modulus of undisturbed soil under different consolidation ratios and its effects on surface ground motion

The dynamic shear modulus for three types of undisturbed soil under different consolidation ratios is presented by using the resonant column test method. Its effects on surface ground motion is illustrated by calculation. The test results indicate that the power function is a suitable form for describing the relationship between the ratio of the maximum dynamic shear modulus due to anisotropic and isotropic consolidations and the increment of the consolidation ratio. When compared to sand, the increment of the maximum dynamic shear modulus for undisturbed soil due to anisotropic consolidation is much larger. Using a one-dimensional equivalent linearization method, the earthquake influence factor and the characteristic period of the surface acceleration are calculated for two soil layers subjected to several typical earthquake waves. The calculated results show that the difference in nonlinear properties due to different consolidation ratios is generally not very notable, but the degree of its influence on the surface acceleration spectrum is remarkable for the occurrence of strong earthquakes. When compared to isotropic consolidation, the consideration of actual anisotropic consolidation causes the characteristic period to decrease and the earthquake influence factor to increase.

A New Elasticity and Finite Element Formulation for Different Young's Modulus When Tension and Compression Loadings

This paper presents a new elasticity and finite element formulation for different Young's modulus when tension and compression loadings in anisotropy media. The case studies, such as anisotropy and isotropy, were investigated. A numerical example was shown to find out the changes of neutral axis at the pure bending beams.

Influence of repeated freeze-thaw on dynamic modulus and damping ratio properties of silty sand

Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the normal operation of railway lines. This study is to obtain the influencing rules of freeze-thaw on the dynamic properties （dynamic strain, confining pressure and compactness） of silty sand. Based on an amount of inner tests, the dynamic modulus and damping ratio properties of silty soil subjected to repeated freeze-thaw cycles were deeply researched and analyzed. The results are as follows： At the same dynamic strain, the relationship of dynamic stress and freeze-thaw cycles presents negative cor- relation, and the relationship of dynamic stress, confining pressure and compactness present positive correlation. The dynamic modulus double decreases while the damping ratio double increases with incremental increase in dynamic strain. The dynamic modulus sharply decreases while the damping ratio increases with incremental increase in freeze-thaw cycles, and then the changes level off after six freeze-thaw cycles. The dynamic modulus increases while the damping ratio decreases as the confining pressure and compactness increase at the same strain level.

NANOINDENTATION OF THIN-FILM-SUBSTRATE SYSTEM DETERMINATION OF FILM HARDNESS AND YOUNG'S MODULUS

In the present paper,the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models.Aluminum film and two kinds of substrates,i.e.glass and silicon,are studied.Nanoindentation XP Ⅱ and continuous stiffness mode are used during the experiments.In order to avoid the influence of the Oliver and Pharr method used in the experiments,the experiment data are analyzed with the constant Young's modulus assumption and the equal hardness assumption.The volume fraction model(CZ model)proposed by Fabes et al.(1992)is used and modified to analyze the measured hardness.The method proposed by Doerner and Nix(DN formula)(1986)is modified to analyze the measured Young's modulus.Two kinds of modified empirical formula are used to predict the present experiment results and those in the literature,which include the results of two kinds of systems,i.e.,a soft film on a hard substrate and a hard film on a soft substrate.In the modified CZ model,the indentation influence angle,(?), is considered as a relevant physical parameter,which embodies the effects of the indenter tip radius, pile-up or sink-in phenomena and deformation of film and substrate.

Dynamic shear modulus and damping ratio characteristics of undisturbed marine soils in the Bohai Sea,China

This paper presents results from a series of stress-controlled undrained cyclic triaxial tests on the undisturbed marine silty clay,silt,and fine sand soils obtained from the Bohai Sea,China.Emphasis is placed on the major factors for predominating the dynamic shear modulus(G)and damping ratio(λ)in the shear strain amplitude(γ_(a))from 10^(-5) to 10^(-2),involving depth,sedimentary facies types,and water content of marine soils.The empirical equations of the small-strain shear modulus(G_(max))and damping ratio(λ_(min))using a single-variable of depth H are established for the three marine soils.A remarkable finding is that the curves of shear modulus reduction(G/G_(max))and the damping ratio(λ)with increasing γ_(a) of the three marine soils can be simply determined through a set of explicit expressions with the two variables of depth H and water content W.This finding is validated by independent experimental data from the literature.At the similar depths,the G value of the marine soils of terrestrial facies is the largest,followed b_(y) the neritic facies,and the G value of the marine soils of abyssal facies is the smallest.The sedimentary facies types of the marine soils have slight effect on theλvalue.Another significant finding is that the shear modulus reduction curves plotted against the γ_(a) of the three marine soils at the similar depths are significantly below those of the corresponding terrigenous soils,while the damping curves plotted against γ_(a) are just the opposite.The results presented in this paper serve as a worthful reference for the evaluation of seabed seismic site effects in the Bohai Sea due to lack of experimental data.

Effect of consolidation ratios on maximum dynamic shear modulus of sands

The dynamic shear modulus (DSM) is the most basic soil parameter in earthquake or other dynamic loading conditions and can be obtained through testing in the field or in the laboratory. The effect of consolidation ratios on the maximum DSM for two types of sand is investigated by using resonant column tests. And, an increment formula to obtain the maximum DSM for cases of consolidation ratio κc>1 is presented. The results indicate that the maximum DSM rises rapidly when κc is near 1 and then slows down, which means that the power function of the consolidation ratio increment κc-1 can be used to describe the variation of the maximum DSM due to κc>1. The results also indicate that the increase in the maximum DSM due to κc>1 is significantly larger than that predicted by Hardin and Black's formula.

A Modified approach for calculating dynamic shear modulus of stiff specimens by resonant column tests

An error analysis of the dynamic shear modulus of stiff specimens from tests performed by a new resonant column device developed by the Institute of Engineering Mechanics, China was conducted. A modified approach for calculating the dynamic shear modulus of the stiff specimens is presented. The error formula of the tests was deduced and parameters that impact the accuracy of the test were identified. Using six steel specimens with known standard stiffness as a base, a revised dynamic shear modulus calculation for stiff specimens was formulated by comparing three of the models. The maximum error between the test results and the calculated results shown by curves from both the free-vibration and the resonant-vibration tests is less than 6%. The free-vibration and resonant-vibration tests for three types of stiff samples with a known modulus indicate that the maximum deviation between the actual and the tested value using the modified approach were less than 10%. As a result, the modified approach presented here is shown to be reliable and the new device can be used for testing dynamic shear modulus of any stiff materials at low shear strain levels

Dynamic Elastic Modulus of Cement Paste at Early Age based on Nondestructive Test and Multiscale Prediction Model

This paper introduced a nondestructive testing method to evaluate the dynamic elastic modulus of cement paste. Moreover, the effect of water-cement ratio and conventional admixtures on the dynamic elastic modulus of cement paste was investigated, in which three kinds of admixtures were taken into account including viscosity modifying admixture （VMA）, silica.fume （SF）, and shrinkage-reducing admixture （SRA）. The experimental results indicate that the dynamic elastic modulus of cement paste increases with decreasing water-cement ratio. The addition of SF increases the dynamic elastic modulus, however, the overdosage of VMA causes its reduction. SRA reduces the dynamic elastic modulus at early age without affecting it in later period. Finally, a multiscale micromechanics approach coupled with a hydration model CEMHYD3D and percolation theory is utilized to predict the elastic modulus of cement paste, and the predictive results by the model are in accordance with the experimental data.

Resilient modulus prediction of soft low-plasticity Piedmont residual soil using dynamic cone penetrometer

Dynamic cone penetrometer（DCP） has been used for decades to estimate the shear strength and stiffness properties of the subgrade soils. There are several empirical correlations in the literature to predict the resilient modulus values at only a specific stress state from DCP data, corresponding to the predefined thicknesses of pavement layers（a 50 mm asphalt wearing course, a 100 mm asphalt binder course and a200 mm aggregate base course）. In this study, field-measured DCP data were utilized to estimate the resilient modulus of low-plasticity subgrade Piedmont residual soil. Piedmont residual soils are in-place weathered soils from igneous and metamorphic rocks, as opposed to transported or compacted soils.Hence the existing empirical correlations might not be applicable for these soils. An experimental program was conducted incorporating field DCP and laboratory resilient modulus tests on "undisturbed" soil specimens. The DCP tests were carried out at various locations in four test sections to evaluate subgrade stiffness variation laterally and with depth. Laboratory resilient modulus test results were analyzed in the context of the mechanistic-empirical pavement design guide（MEPDG） recommended universal constitutive model. A new approach for predicting the resilient modulus from DCP by estimating MEPDG constitutive model coefficients（k;,k;and k;） was developed through statistical analyses. The new model is capable of not only taking into account the in situ soil condition on the basis of field measurements,but also representing the resilient modulus at any stress state which addresses a limitation with existing empirical DCP models and its applicability for a specific case. Validation of the model is demonstrated by using data that were not used for model development, as well as data reported in the literature.

Experimental study on the dynamic modulus of compacted loess under bidirectional dynamic load

The dynamic characteristics of compacted loess are of great significance to the seismic construction of the Loess Plateau area in Northwest China,where earthquakes frequently occur.To study the change in the dynamic modulus of the foundation soil under the combined action of vertical and horizontal earthquakes,a hollow cy-lindrical torsion shear instrument capable of vibrating in four directions was used to perform two-way coupling of compression and torsion of Xi'an compacted loess under different dry density and deviator stress ratios.The results show that increasing the dry density can improve the initial dynamic compression modulus and initial dynamic shear modulus of compacted loess.With an increase in the deviator stress ratio,the initial dynamic compression modulus increases,to a certain extent,but the initial dynamic shear modulus decreases slightly.The dynamic modulus gradually decreases with the development of dynamic strain and tends to be stable,and the dynamic modulus that reaches the same strain increases with an increasing dry density.At the initial stage of dynamic loading,the attenuation of the dynamic shear modulus with the strain development is faster than that of the dynamic compression modulus.Compared with previous research results,it is determined that the dynamic modulus of loess under bidirectional dynamic loading is lower and the attenuation rate is faster than that under single-direction dynamic loading.The deviator stress ratio has a more obvious effect on the dynamic compression modulus.The increase in the deviator stress ratio can increase the dynamic compression modulus,to a certain extent.However,the deviator stress ratio has almost no effect on the dynamic shear modulus,and can therefore be ignored.

EFFECT OF DISPERSION OF MICA IN MATRIX ON YOUNG'S MODULUS OF MICA FILLED POLYETHYLENE

The correlation between Young's modulus of mica-filled high density polyethylene (HDPE), low density polyethylene(LDPE) and the state of dispersion of plasma-treated mica in the polymer matrices was studied. The modulus and the number average diameter of mica aggregates in matrix were determined with tensile testing and image analysis respectively. The interface structure of the filler/matrix and the bulk structure of matrix were examined through the dielectric spectrometry, differential scanning calorimetry (DSC) and dynamic viscoelastic spectrometry. The results show that the Young's modulus of the filial polyethylene depends to a great extent upon the state of dispersion of filler in matrix, but it is independent of the interface structure and bulk structure. The better the dispersion, the higher the Young's modulus.

Anomalies in Young's modulus behavior after annealing in polycrystalline SmS

In this paper,the dependencies of Young's modulus and attenuation decrement on samarium sulfide polycrystals(SmS)under various annealing temperatures are studied by the piezoelectric ultrasonic composite oscillator technique at a frequency of 100 kHz in the temperature range of 80-300 K.A decrease in Young's modulus with an increase of the annealing temperature due to the texturing of the material was revealed.At the same time,attenuation peaks were observed at temperatures about 90 and 125 K,presumably due to Niblett-Wilks and Bordoni relaxations.

RELATION BETWEEN DYNAMIC LOSS MODULUS AND DIFFUSION COEFFICIENT IN A MODIFIED PET FIBER

The mobility of polymer chain segments is shown to play a major role in the diffusion ofdisperse dyes in a copolymerization modified PET system, monoepoxy compoundCH_3 (CH_3),OCH_2CH--CH_2 modified PET. The rate of dye diffusion (diffusion coefficient D) hasbeen related to the time-dependent mechanical property, dynamic loss modulus E', which iscontrolled by the mobility of chain segments. In this modified copolyester system, the variance ofamount of modifier in the copolyester fibers causes the change in disperse dye diffusion coefficientto fiber, and in the dynamic loss modulus of the fibers, but the relationship between the diffusionand the dynamic loss modulus is in agreement with the theoretical relation derived by Bell andDumbleton. The relation obtained in this paper is:Ln D=-2. 28Ln E'+26. 81

Influence of Temperature Conditions on Dynamic Young’s Modulus Testing

The Young’s modulus was measured at high temperatures by impulse excitation of vibration method,and the effects of heating rate,holding time and temperature cycle on the test results were analyzed.The results show that the heating rate has obvious effect on the high temperature Young’s modulus of the green body,but has no obvious effect on that of the sintered products;the holding time of the heating process has no regular effect on the Young’s modulus,and the effect varies with the different products at a certain temperature;the method can also be used to test the Young’s modulus during cooling process.

Theoretical Model of Dynamic Bulk Modulus for Aerated Hydraulic Fluid

Existing models of bulk modulus for aerated hydraulic fluids primarily focus on the effects of pressure and air fraction,whereas the effect of temperature on bulk modulus is disregarded.Based on the lumped parameter method and the full cavitation model,combined with the improved Henry’s law and the air polytropic course equation,a theoretical model of dynamic bulk modulus for an aerated hydraulic fluid is derived.The effects of system pressure,air fraction,and temperature on bulk modulus are investigated using the controlled variable method.The results show that the dynamic bulk modulus of the aerated hydraulic fluid is inconsistent during the compression process.At the same pressure point,the dynamic bulk modulus during expansion is higher than that during compression.Under the same initial air faction and pressure changing period,a higher temperature results in a lower dynamic bulk modulus.When the pressure is lower,the dynamic bulk modulus of each temperature point is more similar to each other.By comparing the theoretical results with the actual dynamic bulk modulus of the Shell Tellus S ISO32 standard air-containing oil,the goodness-of-fit between the theoretical model and experimental value at three temperatures is 0.9726,0.9732,and 0.9675,which validates the theoretical model.In this study,a calculation model of dynamic bulk modulus that considers temperature factors is proposed.It predicts the dynamic bulk modulus of aerated hydraulic fluids at different temperatures and provides a theoretical basis for improving the analytical model of bulk modulus.

Dynamic Modulus of Elasticity of Some Mortars Prepared from Selected Jordanian Masonry Cements

In light of the highly demanding cement market in Jordan, comprehensive studies should be undertaken to investigate the properties of the different cement types. This paper studies the Dynamic modulus of elasticity (DME) at 2, 7 and 28 days in mortars using six cement Jordanian types with CaO contents less than that of the ordinary Portland cements. It was found that the DME has strong relation with compressive strength. At the age of 28 days the mortars had some different values of DME. One important result of our work is that DME at the age of 28 days can be derived from those of the two days mixes. To account for the differences in dynamic modulus of elasticity with time, it is highly recommended to study in detail the mortars petrography under the light microscope. Using the scanning electron microscope (SEM), usually with attachment for chemical analysis at the crystal scale, in addition to X-ray diffraction technique may help characterization of the cement phases qualitatively and quantitatively.

Evaluation of Dynamic Modulus of HMA Sigmoidal Prediction Models and Optimization by Approach of U.S. Mesh Sieve by AFNOR and LC Mesh Sieve

Pavement design tools are not universal. Indeed, in the sizing of pavements in the USA, the prediction models used in the calculation of the dynamic modulus of HMA are not adapted to the characterization of the mineral skeleton of the HMA mix designed with the French method. This article aims to assess the predictive models of the dynamic modulus used in the mechanistic-empirical design for their use in the design of bituminous pavements, and to develop new predictive models taking into account the sieve series LC and AFNOR standards. A total of six types of mixtures were subjected to the determination of complex modulus testing by direct tensile-compression on cylindrical specimens (26-700 LC) over a temperature range (5) and frequency (5) data. Dynamic modulus prediction models |E*| are studied Witczak model 1999 and model Witczak 2006. These models do not take into account the AFNOR or LC mesh sieve, an approach was made in relation to the US mesh sieve to replace ρ200 (0.075 mm), ρ4 (4.76 mm), ρ38 (9.5 mm) and ρ34 (19 mm) respectively by the AFNOR mesh P0.08 (0.08 mm), R5 (5 mm), R10 (10 mm) and R14 (14 mm). The result is the production of two models whose are evaluated by correlation with the values |E*| of modulus measured in the laboratory is satisfactory (R2 = 0.83 respectively R2 = 0.71 and p-value = 0.00). The optimization of these approximate models gave new models with the same frame as the original models and a better correlation with the data observed in the laboratory (respectively R2 = 0. 95 and R2 = 0.91 p-value = 0.00).

Development of a Dynamic Modulus Prediction Model for Hot Mixture Asphalt and Study of the Impact of Aggregate Type and Its Electrochemical Properties

The most famous model known in prediction of dynamic modulus for asphalt concretes is the Witczak and Hirsh models. These models didn’t use the mineralogical and chemical properties of aggregates. Witczak models used the passing or refusal percentage to sieve diameters and Hirsh model used the volumetric analysis. All models developed until now considered that the aggregates were geotechnical conforming to standards. In this study the first mineralogical and chemical properties were considered through the percentage of silica in the rock source of aggregates and the electric aggregate particles charge zeta. Dynamic modulus values used for regression process are determined from complex modulus test on nine asphalt concretes mix designed with aggregate types (basalt of Diack, quartzite of Bakel and Limestone of Bandia). Between Twelve initial inputs, the statistical regression by exclusion process keeps only seven parameters as input for the model. The mineralogical model showed good accuracy with R2 equal to 0.09. The student test on the model parameters showed that all the parameters included in the model were meaningful with good p inferior to 0.05. The Fisher test on the model showed the same result. The analysis of the sensitivity of the mineralogical model to zeta potential showed that the dynamic modulus increases with the positive zeta-potentials and decreases with the negative zeta-potentials. The analysis of the sensitivity of the mineralogical model to the silica showed that the dynamic modulus decreases with the increase of the silica.

Dynamic Flexural Modulus and Low-Velocity Impact Response of Supercomposite^TMLaminates with Vertical Z-Axis Milled Carbon Fiber Reinforcement

In work reported here, the dynamic properties and low-velocity impact response of woven carbon/epoxy laminates incorporating a novel 3D interlaminar reinforcement concept with dense layers of Z-axis oriented milled carbon fiber SupercompositeTM prepregs, are presented. Impulse-frequency response vibration technique is used for non-destructive evaluation of the dynamic flexural modulus (stiffness) and loss factor (intrinsic damping) of woven carbon/epoxy control and SupercompositeTM laminates. Low-velocity punch-shear tests were performed on control and SupercompositeTM laminates according to ASTM D3763 Standard using a drop-weight impact test system. Control panels had all layers of 3K plain woven carbon/epoxy prepregs, with a dense interlaminar reinforcement of milled carbon fibers in Z- direction used in designing the SupercompositeTM laminate—both having same areal density. Impulse-frequency response vibration experiments show that with a 50% replacement of woven carbon fabric in control panel with milled carbon fibers in Z direction dynamic flexural modulus reduced 25% - 30% (loss in stiffness) and damping increased by about the same 25% - 30%. Low-velocity punch-shear tests demonstrated about 25% reduction in energy absorption for SupercompositeTM laminates with the replacement of 50% woven carbon fabric in control panel.