Dynamic Modulus Measurements Research Articles

Preprocessing and postprocessing analysis for hot-mix asphalt dynamic modulus experimental data

Dynamic modulus (|E*|) measurements of hot-mix asphalt (HMA) mixtures are critical for understanding material behavior but present significant challenges due to the complex testing procedures and precision required. While substantial efforts have focused on developing predictive models for |E*|, the critical role of experimental data preprocessing has been largely overlooked in the existing literature. This study addresses this gap by proposing a novel, comprehensive framework for both preprocessing and post-processing of dynamic modulus data. Leveraging the well-established ASU |E*| database and the NCHRP 1–40D Witczak prediction model as benchmarks, we introduce advanced empirical techniques, including probability distribution analysis, scatter and box plots, correlation coefficients, and mutual information metrics, to refine data quality and enhance the interpretability of predictive models. Our approach reveals new insights into the interaction of various input factors and |E*| values, leading to improved model robustness and reliability. The post-processing techniques further substantiate the predictive power of the Witczak model, yielding significant enhancements in accuracy and reliability. This research pioneers a standardized data preparation methodology that sets a new precedent in asphalt material engineering, offering a robust foundation for future |E*| modeling and analysis.

Factors Influencing Measurement of Dynamic Elastic Modulus from Disk-Shaped Concrete Specimen

The decrease in dynamic elastic modulus is a primary indicator of quantitative damage in concrete. To quantitatively assess depth-by-depth damage within a concrete structure, cylindrical specimens obtained through coring can be cut into disk specimens to measure the dynamic elastic modulus of concrete at each depth. To minimize external damage during coring, it is essential to extract cylinders with the smallest possible diameter. In addition, for higher resolution in depth-based damage assessment, creating disk specimens with the smallest possible thickness is necessary. However, there is no information available in the literature on experimental limitation of smallest possible diameter and thickness for dynamic elastic modulus of disk-shaped specimens. This study evaluated whether the dynamic modulus measured from various sizes of concrete disk specimens provided sufficient reliability compared to reference values obtained from cylinders. Moreover, the study examined how the presence of coarse aggregate and variation in the water–cement ratio significantly influenced the dynamic modulus measurement. In addition, test results from impulse excitation technique (IET) and impact resonance (IR) were compared to find a more reliable test method for dynamic elastic modulus of disk specimen. The experimental findings revealed that as the thickness-to-radius ratio of the disk specimens decreased, measured data variation increased. Mortar specimens without coarse aggregates showed less variability compared to concrete specimens, and the variation in dynamic modulus measured by IR was lower than that measured by IET.

Moisture Impact on Static and Dynamic Modulus of Elasticity in Structural Normal-Weight Concretes.

In the case of concrete built into a structure, the static secant modulus of elasticity (Ec,s) is often estimated based on its dynamic value (Ed) measured by the ultrasonic pulse velocity method instead of direct tests carried out on drilled cores. Meanwhile, the prevailing equations applied to estimate Ec,s often overlook the impact of concrete moisture. This study aimed to elucidate the moisture impact across two normal-weight structural concretes differing in compressive strength (51.6 and 71.4 MPa). The impact of moisture content was notably more evident only for the weaker concrete, according to dynamic modulus measurements. In other cases, contrary to the literature reports and expectations, this effect turned out to be insignificant. These observations may be explained by two factors: the relatively dense and homogeneous structure of tested concretes and reduced sensitivity of Ec,s measurements to concrete moisture condition compared to Ed measurements obtained using the ultrasonic method. Additionally, established formulas to estimate Ec,s were verified. The obtained modulus results tested under different moisture conditions of normal-weight concretes were also compared with those of lightweight aggregate concretes of identical volume compositions previously obtained in a separate study.

Application of Generalized S-Transform in the Measurement of Dynamic Elastic Modulus

Resonance is commonly used for in situ measurement of the dynamic elastic modulus to evaluate the strength of concrete samples. Many researchers are also exploring the application of this convenient measurement technology for safety monitoring. Nevertheless, the presence of cracks and variations in curing conditions within samples can impact the resonance frequency range, potentially leading to potential inaccuracies in measurements. In order to improve the measurement accuracy of resonance frequency, this study introduces the Generalized S-Transform (GST) algorithm for measuring the dynamic elastic modulus, which utilizes its high time-frequency resolution to scan the power peak-point in non-stationary and transient excitation signals to determine the resonance frequency. For concrete materials with lower consistency, the experimental results verify the high accuracy of this algorithm in measuring resonance frequency compared with Fast Fourier Transform (FFT). This provides a reference for using the algorithm to measure the dynamic elastic modulus in civil engineering applications, such as buildings and bridges.

Temperature Dependence of Kinetic Friction: A Handle for Plastics Sortation?

Sortation is a crucial step in mechanical recycling of post-consumer plastics (PCR) whereby properties such as density or spectral signature are used to separate plastics. However it is difficult to sort polyolefin flakes at high throughput by these properties. We ask whether the frictional properties of plastics as a function of temperature may be used as an alternate sorting property. However, fundamental studies of friction at temperatures near their melting points are limited. Here we measure the temperature dependence of kinetic friction for three common polyolefins (high and low den- sity polyethylene and polypropylene) as well as polyethylene terephthalate (PET), focusing on the softening/melting regime. The results are augmented by differential scanning calorimetry and temperature dependence measurements of both dynamic modulus and and probe tack. For the polyolefins, we find strong increases in the coefficients of kinetic friction during temperature ramps in the melting/softening regime. For the PET, we report a notable peak in the kinetic friction which we associate with the glass transition and cold-crystallization. We discuss the enhanced friction in the context of rub- ber friction, which exhibits comparable coefficients of kinetic frictions.

Modeling calcium diffusion and crosslinking dynamics in a thermogelling Alginate-Gelatin-Hyaluronic acid ink: 3D bioprinting applications

Alginate-based inks are widely used in 3D bioprinting. Its crosslinking by Ca2+ ions is extremely important to achieve scaffolds with optimal mechanical properties. Notably, despite previous studies on calcium diffusion in alginate systems, there have been no reported data regarding the effect of temperature on the diffusion and crosslinking dynamics of thermogelling alginate-based hydrogels. This study focuses on investigating the kinetics of the crosslinking front and Ca2+ diffusion within a matrix of Alginate-Gelatin-Hyaluronic acid ink, exploring the impact of temperature and Ca2+ concentration. The Ca2+ diffusion rate or ink crosslinking rate increase as the crosslinker concentration and ink temperature increase. Additionally, the mechanical properties of the scaffolds, assessed through compression, tension, and dynamic tests, were correlated with the crosslinking time.The innovative aspect of this study lies in the development of a code that simulates the diffusion of Ca2+ ions from the exterior to the interior of a hydrogel structure. Specifically, the code facilitates the calculation of the crosslinking time for a cylindrical structure up to a specified thickness, providing valuable insights for the production of airways or blood vessels. Furthermore, the Python script, incorporating the numerical model, manages to simulate the crosslinking dynamics of scaffolds of any shape, and properly fits the rheological measurements of dynamic moduli during the crosslinking process. This represents a significant advance for the precise and controlled scaffold fabrication process using 3D bioprinting.

Dynamic Young's modulus measurement by incident wave extracting for viscoelastic materials under variable water pressure

This study presents a method for measuring the complex Young's modulus of viscoelastic materials under several water pressures. A Butterworth impulse is generated by an electromagnetic shaker and is employed to excite a bar-like sample which was attached inside the pressure vessel. The broadband mechanical parameters (including the storage modulus and loss factor) under variable water pressure conditions (0.1-5MPa) for two types of viscoelastic materials were obtained by incident wave extracting. The experimental results agree well with those obtained using a standard dynamic mechanical thermal analyzer and those obtained using resonant method, which proved that the method proposed in this study can directly determine the Young's modulus at frequencies ranging from 500 to 5000Hz under variable water pressure. This method provides simplified processing for underwater dynamic mechanical parameters measurements.

Specimen size effect on dynamic modulus measurement of Cold recycled and full depth reclamation mixtures

Dynamic modulus was measured using large-scale (LS) and small-scale (SS) specimens of four cold recycled (CR) and one full depth reclamation mixtures. The study found emulsified mixtures showed similar and repeatable dynamic modulus (E*) results with both specimen geometries (<15% difference) and foamed mixtures showed poor agreement between specimens (>24% difference), likely due to the differences in the mix matrices. The mechanistic-empirical pavement design analysis showed that E* differences in LS and SS of CR mixtures with foam resulted in error in asphalt concrete (AC) rutting predictions for sections with a thin surface layer (25 mm [1 in.]) and did not affect rutting predictions once the surface layer thickness was above 76 mm (3.0 in.). An empirical SS to LS shift factor method is presented.

Effect of Moisture Condition of Structural Lightweight Concretes on Specified Values of Static and Dynamic Modulus of Elasticity.

The dynamic modulus of elasticity (Ed), specified by ultrasonic pulse velocity measurements, is often used, especially for concrete built into construction, to estimate the static modulus of elasticity (Ec,s). However, the most commonly used Equations for such estimations do not take into account the influence of concrete moisture. The aim of this paper was to establish this influence for two series of structural lightweight aggregate concrete (LWAC) varying in their strength (40.2 and 54.3 MPa) and density (1690 and 1780 kg/m3). The effect of LWAC moisture content turned out to be much more pronounced in the case of dynamic modulus measurements than for static ones. The achieved results indicate that the moisture content of the concrete should be taken into consideration in modulus measurements as well as in Equations estimating Ec,s on the basis of Ed specified by the ultrasonic pulse velocity method. The static modulus of LWACs was lower on average by 11 and 24% in relation to dynamic modulus, respectively when measured in air-dried and water-saturated conditions. The influence of LWAC moisture content on the relationship between specified static and dynamic moduli was not affected by the type of tested lightweight concrete.

Direct monitoring of porosity evolution by dynamic modulus measurements: Three case studies

Porous materials are playing an increasingly relevant role in several fields and industrial sectors with structural and functional applications. Their properties critically depend on the relative density and pore morphology thus it is of great importance monitoring the variations of such structural features. Among the experimental techniques commonly used for investigating the microstructure evolution of porous materials, Mechanical Spectroscopy (MS) provides damping and dynamic modulus of the material during heat treatments. In this work three cases of possible pore structure evolution in different metallic alloys have been examined by MS: (i) growth and coalescence of pores, (ii) closure of pores of nanometric size and (iii) no change of porosity.The results show how dynamic modulus measurements can be successfully employed for a direct monitoring of porosity variations during heating. The technique is quite sensitive and allows to identify the temperature range where pore evolution takes place providing information useful to orientate heat treatments of porous materials.

Thermomechanical Responses of Microcracks in a Honeycomb Particulate Filter

Manufacturing honeycomb‐structured catalysts require a careful understanding of the microstructure of the solid substrate and its dependence on thermal‐processing conditions. Herein, it is the thermal responses of microcracks in an uncoated microcracked aluminum titanate honeycomb catalyst is investigated by analyzing the material's resonance frequency using the high‐temperature impulse excitation technique. The resonance frequencies are presented as Young's modulus values to avoid sample size effects. Dynamic Young's modulus measurements show closed‐loop hysteresis due to microcracks healing and reopening, causing a reversible response. The hysteresis is further used to understand microcracks’ dependence on critical thermal‐processing conditions used in a catalyst manufacturing plant, including peak operating temperature (800–1000 °C), dwell period (1–3 h), and heating rates (1–5 °C min−1). Microcracks are observed to have two healing responses: instantaneous and delayed healing. Both responses significantly influence the design of catalyst manufacturing. Complete reopening of microcracks from their healing temperature (1150 °C) is a very time‐consuming process (50–60 h). However, it is shown in the analysis that microcrack relaxation is a critical phenomenon that must be considered in quality‐controlled environments.

Measurement of Dynamic Elastic Modulus and Poisson’s Ratio of Sugarcane Core by Cantilever Beam Vibration Method

Measurement of Dynamic Elastic Modulus and Poisson’s Ratio of Sugarcane Core by Cantilever Beam Vibration Method

Thermal and energy analysis of DMTA tests

This paper investigates the suitability of the isothermal linear viscoelastic framework to describe the behavior of polymers observed during DMTA tests. A good interpretation of these tests is important because, in practice, they are used to construct master curves using the time-temperature superposition principle at small strain. These curves are then considered to predict the material behavior under experimentally unreachable thermal and/or loading frequency conditions. Currently, the DMTA protocol neglects the temperature variations induced by the deformation of polymers. We wonder if these temperature variations can have an influence on the measurement of dynamic moduli. To answer this question, quantitative infrared techniques were developed and used to assess small temperature variations of samples undergoing cyclic loadings during mechanical spectrometry tests. Thermal and mechanical data were used to quantify the viscous dissipated and the thermoelastic coupling energies that can be both associated with the hysteretic stress-strain response of polymers. Energy balances were then performed to quantify the relative importance of dissipative and thermoelastic coupling heat sources. From the energy standpoint, it is found that the thermoelastic energy rate was dozens of times higher than the dissipation. Especially at low frequencies, thermoelastic effects can have a greater influence on the loss modulus value than viscosity.

Microscopy-based approach for measuring asphalt film thickness and its impact on hot-mix asphalt performance

The thickness of the asphalt binder’s film surrounding the aggregate particles in Hot-Mix Asphalt (HMA) plays a significant role in the durability of the pavement. This study introduces a new approach for determining the film thickness of the asphalt binder using a reflective digital stereo microscope. Image analysis was performed using the thresholding process to distinguish the aggregates, the voids, and the asphalt binder from each other using ImageJ software. Six different mixtures were investigated using this approach. The same materials were used to fabricate those mixtures but with different aggregate gradations. The thickness of the asphalt film was correlated to the dynamic modulus (E*) and rutting measured by flow number. The analysis showed that asphalt film thickness plays a major role in the dynamic modulus measurements at intermediate and high-temperature ranges. The correlation of asphalt film thickness with rutting showed a significant decrease in the flow number as the asphalt film thickness increased. This was more significant for gap-graded and Bailey’s gradation asphalt mixtures compared to the dense-graded asphalt mixtures. Finer dense gradations were slightly less affected by the asphalt film thickness increase compared to the coarser gradations.

Size effects on the dynamic indentation modulus of films

The dynamic mechanical characteristics of viscoelastic films play a significant role in the load-bearing functions of various engineering and natural composite materials systems. Identifying these film characteristics is a prime objective in both fundamental and applicative materials science fields. However, as the film thickness decreases, its analysis by dynamic nanoindentation methods becomes convoluted due to the emergence of mechanical coupling between the film and its underlying substrate. These yet unexplored size effects pose major limitations in approaching the elemental mechanical characteristics of thin films. Here, we analyze the film size effects on its dynamic indentation modulus by theoretical modeling and Finite-Element simulations. We develop compact analytical formulae that link the indentation modulus magnitude, loss coefficient, storage modulus, and loss modulus to those of the pristine film, draw functional insights into the energy-storage and energy-dissipation capabilities of the integrated film–substrate laminate, and outline an approach to back-calculate the elemental film characteristics via simple linear scaling of its dynamic indentation modulus measurements. Our analysis generally holds for synthetic and biological film materials—paving the way to identify the dynamic mechanical characteristics of various thin-film configurations, such as polymeric assemblies, functional surfaces, and biomechanical coatings.

Influence of Confinement Pressure and Rest Periods on Measurement of Dynamic Modulus of Bituminous Mixtures

AbstractIn the AASHTO T-378 protocol for computing dynamic modulus and phase angle, the bituminous mixture sample is subjected to a continuous loading from high frequency to low frequency. The post...

Determination of soil deformation modulus using the static and dynamic circular plate load test

The increase in mining activity in the Bor basin in recent years has also required the construction of new mining facilities. The construction of numerous embankments and dams, as parts of these facilities, required a constant control of compaction the coarse-grained and fine-grained materials from which they were built. The compaction check was performed using the static and dynamic circular plate test. The results of measurement and correlation of static and dynamic deformation modulus for multiple types of materials, used during construction, are presented.

Measurement of Dynamic Elastic Modulus and Poisson's Ratio of Chemically Strengthened Glass.

Glass with strong durability and transparency has been in the spotlight in various fields, including displays. Elastic and shear moduli and Poisson’s ratio are important properties of glasses. The purpose of this study is to evaluate the change in mechanical properties, such as the dynamic elastic modulus and Poisson’s ratio, with respect to the chemical strengthening time of glass for display applications, as measured by static and dynamic methods. The basic measurement principle of the dynamic method is to measure acoustic speed or resonant frequency using an ultrasonic generator. The mechanical properties of both non-strengthened and chemically strengthened glasses were investigated. It was found that the strength of the chemically strengthened glass decreased when chemical strengthening time increased. Chemical strengthening increased the bending strength and decreased the elastic modulus due to the introduction of compressive residual stress at the surface.

Smecticlike rheology and pseudolayer compression elastic constant of a twist-bend nematic liquid crystal

In twist-bend nematic (N\textsubscript{TB}) liquid crystals (LCs), the mean molecular orientation exhibits heliconical structure with nanoscale periodicity. On the mesoscopic scale, N\textsubscript{TB} resembles layered systems (like smectics), where the helical pitch is equivalent to "pseudo-layers" without a true mass density wave. We study rheological properties of a N\textsubscript{TB} phase and compare the results with those of an usual SmA phase. Analysing the shear response and adapting a simplified physical model for rheology of defect mediated lamellar systems we measure the pseudo-layer compression elastic constant $B_{eff}$ of N\textsubscript{TB} phase from the measurements of dynamic modulus $G^{*}(\omega)$. We find that $B_{eff}$ of the N\textsubscript{TB} phase is in the range of $10^{3}-10^{6}$ Pa and it follows a temperature dependence, $B_{eff}\sim (T_{TB}-T)^{2}$ as predicted by the recent coarse-grained elastic theory. Our results show that the structural rheology of N\textsubscript{TB} is strikingly similar to that of the usual smectic LCs although the temperature dependence of $B_{eff}$ is much faster than smectic LCs as predicted by the coarse-grained models.

Study on the service life prediction of freeze–thaw damaged concrete with high permeability and inorganic crystal waterproof agent additions based on ultrasonic velocity

Based on a rapid freeze–thaw test of inner-doped silicon-ash concrete specimens that were coated using three different externally coated inorganic coating methods, ultrasonic wave velocity and dynamic elastic modulus measurements were employed. The characteristics of the ultrasonic wave velocity attenuation and dynamic elastic modulus of the concrete utilizing three types of inorganic coating methods under the effect of freeze–thaw cycles were analysed. Based on the theory of damage mechanics and the evolution equation for freeze–thaw or corrosion damaged concrete, the damage evolution equations of the relative dynamic elastic modulus for three types of inorganic coated concrete were verified by a large amount of experimental data under the action of a single freeze–thaw factor. According to the relative dynamic elastic modulus formula, based on the ultrasonic wave velocity of Ababneh, the relative ultrasonic velocity was determined to be 0.7746 when the relative dynamic elastic modulus was 0.60. The equivalent freeze–thaw damage model of the ultrasonic wave velocity of the concrete was established, the concept of relative ultrasonic wave velocity was proposed, the relative dynamic elastic modulus method was verified, and the relative P-wave velocity and relative shear wave velocity of Ababneh for the three types of concrete under the effect of freeze–thaw cycles was determined for service life prediction. The above three methods can accurately predict the service life of concrete. Ultimately, the service life of concrete materials in different mix proportions and use areas will be able to be predicted using ultrasonic non-destructive testing in the future.