Search

To clarify sawn-timber quality and those among-family variations of hinoki cypress (Chamaecyparis obtusa), modulus of elasticity (MOE) and modulus of rupture (MOR) were evaluated for 97 pieces of 38 by 89 mm sawn timber produced from half-sib families planted in a progeny test stand at Chiba, Japan. Correlations were evaluated on mechanical properties in standing trees and logs with MOE and MOR in the sawn timber. Elastic properties, such as dynamic Young's modulus of logs and MOE, were affected by genetic factors compared with air-dry density and MOR. The 5% tolerance limits at a 75% confidence level (f0.05) of MOE and MOR were 8.03 GPa and 39.4 MPa, respectively. The f0.05 values of MOR exceeded the characteristic value of the sawn timber in visual grading class SS of Japanese Agricultural Standard for the JS-I. Visual grading of the sawn timber was effective for eliminating timber with lower MOE. Stress-wave velocity and dynamic Young's modulus of log and timber were significantly correlated with MOE of sawn timber. Correlation coefficients were also significant between MOR of sawn timber and dynamic Young's modulus or MOE. [ABSTRACT FROM AUTHOR]

The equiatomic high-entropy alloy of composition of CrNiCoFeMn with an FCC crystal structure was prepared by either induction melting or additive manufacturing with a selective laser melting (SLM) process, starting from mechanically alloyed powders. The as-produced samples of both kinds were cold worked, and in some cases re-crystallized. Unlike induction melting, there is a second phase, which is made of fine nitride and Cr-rich σ phase precipitates, in the as-produced SLM alloy. Young's modulus and damping measurements, as a function of temperature in the 300–800 K range, were performed on the specimens that were cold-worked and/or re-crystallized. Young's modulus values of (140 ± 10) GPa and (90 ± 10) GPa were measured from the resonance frequency of free-clamped bar-shaped samples at 300 K for the induction-melted and SLM samples, respectively. The room temperature values increased to (160 ± 10) GPa and (170 ± 10) GPa for the re-crystallized samples. The damping measurements showed two peaks, which were attributed to dislocation bending and grain-boundary sliding. The peaks were superposed on an increasing temperature background. [ABSTRACT FROM AUTHOR]

The dynamic Young’s modulus (Edyn) is a parameter needed for optimizing different aspects related to oil well designing. Currently, Edyn is determined from the knowledge of the formation bulk density, in addition to the shear and compressional velocities, which are not always available. This study introduces three machine learning (ML) models, namely, random forest (RF), adaptive neuro-fuzzy inference system with subtractive clustering (ANFIS-SC), and support vector regression (SVR), for estimation of the Edyn from only the real-time available drilling parameters. The ML models were learned on 2054 datasets collected from Well-A and then tested and validated on 871 and 2912 datasets from Well-B and Well-C, respectively. The results showed that the three optimized ML models accurately predicted the Edyn in the three oil wells considered in this study. The optimized SVR model outperformed both the RF and ANFIS-SC models in evaluating the Edyn in all three wells. For the validation data, the Edyn was assessed accurately with low average absolute percentage errors of 3.64%, 6.74%, and 1.03% using the optimized RF, ANFIS-SC, and SVR models, respectively.

The equiatomic high-entropy alloy of composition of CrNiCoFeMn with an FCC crystal structure was prepared by either induction melting or additive manufacturing with a selective laser melting (SLM) process, starting from mechanically alloyed powders. The as-produced samples of both kinds were cold worked, and in some cases re-crystallized. Unlike induction melting, there is a second phase, which is made of fine nitride and Cr-rich σ phase precipitates, in the as-produced SLM alloy. Young’s modulus and damping measurements, as a function of temperature in the 300–800 K range, were performed on the specimens that were cold-worked and/or re-crystallized. Young’s modulus values of (140 ± 10) GPa and (90 ± 10) GPa were measured from the resonance frequency of free-clamped bar-shaped samples at 300 K for the induction-melted and SLM samples, respectively. The room temperature values increased to (160 ± 10) GPa and (170 ± 10) GPa for the re-crystallized samples. The damping measurements showed two peaks, which were attributed to dislocation bending and grain-boundary sliding. The peaks were superposed on an increasing temperature background.

Log characteristics and basic density were evaluated in four common Mongolian softwoods, Pinus sylvestris L., Pinus sibirica Du Tour, Picea obovata Ledeb., and Larix sibirica Ledeb. by developing the linear or nonlinear mixed-effects models for longitudinal and radial variations of measured characteristics. Total of 19 trees from four species were used in this study. Log taper and juvenile wood percentage increased from base to treetop in all species, except for log taper in Pinus sylvestris. Dynamic young's modulus of logs decreased from base to treetop, and the mean values were 7.81, 5.74, 7.12, and 8.78 GPa for Pinus sylvestris, Pinus sibirica, Picea obovata, and Larix sibirica, respectively. Basic density increased (Pinus sylvestris and Larix sibirica) or decreased (Pinus sibirica and Picea obovata) and then became stable values. The estimated whole tree values of basic density in juvenile wood significantly differed from those in mature wood for all species. [ABSTRACT FROM AUTHOR]

Young’s modulus (E) is essential for predicting the behavior of materials under stress and plays an important role in the stability of surface and subsurface structures. E has a wide range of applications in mining, geology, civil engineering, etc.; for example, coal and metal mines, tunnels, foundations, slopes, bridges, buildings, drilling, etc. This study developed a novel machine learning regression model, namely an extreme gradient boosting (XGBoost) to predict the influences of four inputs such as uniaxial compressive strength in MPa; density in g/cm3; p-wave velocity (Vp) in m/s; and s-wave velocity in m/s on two outputs, namely static Young’s modulus (Es) in GPa; and dynamic Young’s modulus (Ed) in GPa. Using a series of basic statistical analysis tools, the accompanying strengths of each input and each output were systematically examined to classify the most prevailing and significant input parameters. Then, two other models i.e., multiple linear regression (MLR) and artificial neural network (ANN) were employed to predict Es and Ed. Next, multiple linear regression and ANN were compared with XGBoost. The original dataset was allocated as 70% for the training stage and 30% for the testing stage for each model. To improve the performance of the developed models, an iterative 10-fold cross-validation method was used. Therefore, based on the results XGBoost model has revealed the best performance with high accuracy (Es: correlation coefficient (R2) = 0.998; Ed: R2 = 0.999 in the training stage; Es: R2 = 0.997; Ed: R2 = 0.999 in the testing stage), root mean square error (RMSE) (Es: RMSE = 0.0652; Ed: RMSE = 0.0062 in the training stage; Es: RMSE = 0.071; Ed: RMSE = 0.027 in the testing stage), RMSE-standard deviation ratio (RSR) index value (Es: RSR = 0.00238; Ed: RSR = 0.00023 in the training stage; Es: RSR = 0.00304; Ed: RSR = 0.001 in the testing stage) and variance accounts for (VAF) (Es: VAF = 99.71; Ed: VAF = 99.99 in the training stage; Es: VAF = 99.83; Ed: VAF = 99.94 in the testing stage) compared to the other developed models in this study. Using a novel machine learning approach, this study was able to deliver substitute elucidations for predicting Es and Ed parameters with suitable accuracy and runtime.

The purpose of this study is to investigate the fractural behavior of lead (Pb)-free material containing bismuth (Bi) that was developed to replace the Pb included in sintered copper (Cu)-based alloy for plain bearings. Mechanical properties and microstructure of two different sintered Cu-based alloys (CuSn10Pb10 and CuSn10Bi7) were compared and analyzed. Under tensile load, a CuSn10Pb10 layer is decomposed into powder and changed to form pores leading to an expansion. Therefore, even after tensile elongation, the matrix itself did not stretch, with no work hardening. However, in the case of CuSn10Bi7, a Bi kept its original shape, resulting in it being the same length as the steel plate, where the hardness and strength increased due to the effect of work hardening. These results suggested that the performance of the alloys was different under a high tensile load, where plain bearings usually undergo tensile deformation.

The derivation of geomechanical properties from petrophysical/geophysical data is not only of great importance in the oil industry but also in mining, geothermal projects and tunnelling, for reduction of costs and to improve security. For the oil industry and geothermal sector, it is mainly important for drilling rate and the stability of the borehole and, as a result, the economic factor. A key issue is that geomechanical properties, which can support a better planning of a project, cannot be measured in the borehole or on the surface directly. In this study, the focus is put on anisotropic effects on the correlation between static and dynamic properties, which is neglected in most studies but important because values can vary extremely. Therefore, measurements in the geotechnical laboratory of compressional and shear wave velocity during uniaxial compression strength test were taken. Additionally, typical properties like bulk and grain density as well as porosity were determined too. Different samples (carbonate–silica schist, marble and phyllite) from the "Zentrum am Berg"-research tunnelling centre at the "Erzberg" in Austria were used. Shown are correlations between uniaxial compression strength and compressional wave velocity as well as for static and dynamic Young's modulus including their anisotropic effect. The results are promising and provide an opportunity for further applications on log data. [ABSTRACT FROM AUTHOR]

Featured Application: The determination of the dynamic Young's modulus by means of low-cost and non-destructive measurement techniques may represent an advance in the study of construction materials. Its application to the field of mortars made with recycled aggregates and the evolution of its mechanical properties has special relevance. This work presents a new method to determine the evolution of the dynamic Young's modulus (MOE) from small mechanical disturbances caused by cement mortar samples and whose value is collected using a low-cost Arduino accelerometer. The results obtained are correlated with measurements made using traditional ultrasound techniques, in addition to the evolution of MOE being related to the variation in mechanical properties that cement mortars experience over time. In this way, in this work, a secure application method is presented that allows us to advance the knowledge of construction materials with the incorporation of construction and demolition waste (CDW) and—more specifically—of cement mortars made with aggregates recycled from ceramic or concrete waste. [ABSTRACT FROM AUTHOR]

While expansive reaction due to the Alkali-Silica Reaction (ASR) and Delayed Ettringite Formation (DEF) have been found to be correlated and the appearances of their cracking patterns are similar, the dominance of DEF or ASR on the expansion is still unknown. However, it is generally believed that ASR and DEF cause crack formation leading to a deleterious effect on concrete. This study investigated the expansion due to ASR, DEF and their combination coupled with the dynamic Young's modulus (ED) and water absorption in concrete test specimens, some of which contained reactive aggregates through a replacement of 30 wt% of the coarse aggregate. K2SO4 and CaSO4 were further added (2.5 wt% SO3 addition) to study the effect of reactive metal ions with sulphate ion on ASR and DEF. Some specimens were cured at an elevated temperature of 90 °C at the early age to accelerate the DEF expansion. The specimens with the addition of SO3 showed higher expansion and lower ED as compared to those without SO3, regardless of the curing temperature. The expansion was significant and rapid with the reduction of ED when reactive aggregate and K2SO4 were used. According to the expansion with ED and moisture absorption, it is indicated that ASR may promote DEF to cause the expansion and subsequent damage after hardening when adequate sulphate and a high temperature are concurrently present. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the statistical correlation between the static and dynamic Young’s modulus of prasinites, a metabasic rock type that outcrops at various localities in the southern part of the Attica peninsula. A total of 39 cylindrical specimens was prepared and an extensive experimental program was carried out to determine the static and dynamic deformational properties for each specimen. Using ordinary least squares regression techniques, a new empirical linear equation was established between the aforementioned properties that can be used in the study region, or elsewhere where metabasic rocks with similar characteristics are investigated.

This study aims to investigate whether it is possible to predict the modulus of elasticity (MOE) and modulus of rupture (MOR) of lumber produced from different heights using the stress-wave velocity of standing trees or the dynamic Young's modulus of logs in Siberian larch (Larix sibirica). A total of 190 pieces of lumber (38 by 89 mm in cross section) were cut from 111 logs obtained from 25 standing trees. Significant positive correlation coefficients were found between the stress-wave velocity of standing trees and MOE (r = 0.776) and MOR (r = 0.702) of this lumber. The dynamic Young's modulus of the logs also correlated significantly with MOE (r = 0.745) and MOR (r = 0.584) values. The results obtained in the present study suggest that stress-wave velocity and dynamic Young's modulus are useful for selecting superior trees in tree breeding and sorting logs for producing structural lumber. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the effects of glass fiber (GF) of PA66-GF30 orientation on very high cycle fatigue (HVCF) life and also to develop an optimized test apparatus such as measurement of dynamic elastic modulus and design of test specimens. Dynamic elastic modulus, tensile strength and fatigue strength tests were conducted at room temperature based on GF orientation (0°, 45°, 90°). Conventional fatigue (3 Hz) and ultrasonic fatigue (20 kHz) tests were performed at the same stress ratio (R = −1). Fracture surface observation showed that GF 0° exhibited a higher fatigue strength in comparison with GF 45 and 90°. Various defects such as voids and microcracks to the load direction around the GF end or debonding in glass fiber reinforced plastic (GFRP) and the slope change in very long life regime of S –N diagram. [ABSTRACT FROM AUTHOR]

The development of dental restorative materials that mimic tooth-like properties provided by graded structures, aesthetics and properties such as strength, damping capacity and the ability for a continuous remodeling according to the biomechanical solicitation is a great challenge. In this work, damping capacity and dynamic Young's modulus of Y-TZP/porcelain composites for all-ceramic dental restorations were studied. These mechanical properties were assessed by dynamic mechanical analyses (DMA) at frequencies of 1, 5 and 10 Hz, over a temperature ranging from 0 to 60 °C, simulating extreme conditions when a cold or hot drink is experienced. The results showed that porcelain and porcelain-matrix composites exhibited higher damping capacity while Y-TZP and Y-TZP-matrix composites presented higher dynamic Young's modulus. Furthermore, while damping capacity is strongly influenced by the temperature, no significant difference in dynamic Young's modulus was found. For both damping and modulus properties, no significant influence of frequency was found for the tested materials. Based on the obtained results and also on the known advantages of the graded Y-TZP/porcelain structures over traditional bi-layer solutions (e.g., improved bending strength, enhanced mechanical and thermal stress distribution), a novel design of all-ceramic restoration with damping capacity has been proposed at the end of this study. A positive impact on the long-term performance of these all-ceramic restorations may be expected. Image 1 • Porcelain matrix composites exhibited higher damping capacity. • Zirconia-rich composites demonstrated higher dynamic Young's modulus. • Dynamic Young's modulus was not influenced by tested frequencies and temperature. • Different damping behaviors with increasing temperature were observed. • From results a novel bio-inspired design was proposed for all-ceramic restorations. [ABSTRACT FROM AUTHOR]

Abstract Conversely to natural teeth, where periodontal ligament (PDL) and pulp works as a damper reducing the effect of the stress on surrounding structures, when natural teeth is lost and replaced or restored the biting forces are directly transmitted to the bone or affect the integrity of the adjacent bottom layers. In this study, damping capacity and dynamic Young's modulus of CoCrMo-porcelain composites for dental restorations were evaluated. Dynamic Young's modulus and damping capacity of materials were assessed by dynamic mechanical analyzes (DMA) at 1 and 10 Hz frequencies, over a temperature ranging (18–60 °C). Results show that by reinforcing dental porcelain with metallic particles, producing ceramic matrix composites (CMCs) with 20 vol% and 40 vol% of metallic particles, the damping capacity and dynamic Young's modulus are improved. A decrease on both properties of the metal matrix composites (MMCs) with increasing ceramic particles content (from 20 vol% to 40 vol% of ceramic phase) was observed for all the studied frequencies and temperatures. While damping capacity is strongly dependent on frequency, no significant difference in dynamic Young's modulus was found. Results show that besides the yet reported advantages of the bio-inspired functionally graded restorations over traditional bilaminate ones, traduced by improved veneer to substrate adhesion and by the enhanced thermal and mechanical stress distribution, these restorations can also display improved behavior as regard to a damping capacity, which may have a positive impact in the long-term performance of implant – supported prosthesis. Graphical abstract fx1 Highlights • All CoCrMo-porcelain composites and monolithic materials were successfully produced by hot pressing technique. • Both damping capacity and dynamic Young's modulus are dependent on temperature. • A pronounced influence of frequency was not found in dynamic Young's modulus when compared with damping capacity. • From results it is possible to tailor local properties to mimic natural teeth by selecting different materials combination. • A bio-inspired FGM design is proposed for dental restoration. [ABSTRACT FROM AUTHOR]

Highlights • Ti 2 AlC significantly contributes to the damping capacity and to dynamic moduli of composites. • The formation of interfacial robust amorphous magnesium layer gives rise to the transformed tensile fracture mechanisms. • A high activation energies (H) of damping peaks for composites was calculated to 128 kJ/mol. Abstract The evolutions with the temperature of damping capacities and dynamic Young's moduli of ternary Ti 2 AlC particles reinforced AZ91D composites were investigated. This work has highlighted that Ti 2 AlC significantly contributes to the damping capacity and to dynamic moduli of composites. With increasing temperature, especially above 200°C, the interfacial damping capacity becomes dominant and dynamic moduli of composites decrease. These trends were revealed from the transformed tensile fracture mechanisms. At room temperature, Ti 2 AlC particles delaminated without any decohesion between Ti 2 AlC particles and the Mg matrix. However, the interfacial decohesion occurred above 200°C. One explanation of this change of decohesion mechanism could be ascribed to the inherent structure of the Ti 2 AlC MAX phase and to the formation of a robust amorphous magnesium layer at the interface between Ti 2 AlC and magnesium matrix that was evidenced by HRTEM. This amorphous layer further gives rise a high activation energies (H) of damping peaks for composites, which was calculated to 128 kJ/mol. This value is higher than those calculated for SiC or graphite reinforced AZ91D composites, making Ti 2 AlC particles particularly interesting for application in reinforcing magnesium composites. [ABSTRACT FROM AUTHOR]

This work presents a new method to determine the evolution of the dynamic Young’s modulus (MOE) from small mechanical disturbances caused by cement mortar samples and whose value is collected using a low-cost Arduino accelerometer. The results obtained are correlated with measurements made using traditional ultrasound techniques, in addition to the evolution of MOE being related to the variation in mechanical properties that cement mortars experience over time. In this way, in this work, a secure application method is presented that allows us to advance the knowledge of construction materials with the incorporation of construction and demolition waste (CDW) and—more specifically—of cement mortars made with aggregates recycled from ceramic or concrete waste.

The dynamic Young's modulus (Ed) and moisture content (MC) were determined for two tropical wood species, Gymnacranthera eugenifolia and Sindora sp. using the free-free vibration method. The wood species were tested at the sap, median, and internal regions. The dynamic Young's modulus was found to be linearly correlated to the radial distance, with Ed gradually increasing with respect to the reduction in radial distance to the centre of the wood. Linear correlation was observed between the radial distance and Ed, with Ed gradually decreasing with respect to the radial distance from the centre. For Sindora sp. and Gymnacranthera eugenifolia, Ed ranged from 0.8 to 2.4 GPa and 0.9 to 1.6 GPa, respectively. Moisture content in Sindora sp. displayed a broad range, from 10 to 20 wt.%, while Gymnacranthera eugenifolia displayed a narrower range from 8 to 15 wt.%. Free-free flexural vibration testing is a fast, inexpensive, and reliable method for determining Ed. However, further studies are needed to investigate the acoustic qualities of these woods, such as the speed of sound and damping within the wood. [ABSTRACT FROM AUTHOR]

The estimation of the in situ stresses is very crucial in oil and gas industry applications. Prior knowledge of the in situ stresses is essential in the design of hydraulic fracturing operations in conventional and unconventional reservoirs. The fracture propagation and fracture mapping are strong functions of the values and directions of the in situ stresses. Other applications such as drilling require the knowledge of the in situ stresses to avoid the wellbore instability problems. The estimation of the in situ stresses requires the knowledge of the Static Young's modulus of the rock. Young's modulus can be determined using expensive techniques by measuring the Young's modulus on actual cores in the laboratory. The laboratory values are then used to correlate the dynamic values derived from the logs. Several correlations were introduced in the literature, but those correlations were very specific and when applied to different cases they gave very high errors and were limited to relating the dynamic Young' modulus with the log data. The objective of this paper is to develop an accurate and robust correlation for static Young's modulus to be estimated directly from log data without the need for core measurements. Multiple regression analysis was performed on actual core and log data using 600 data points to develop the new correlations. The static Young's modulus was found to be a strong function on three log parameters, namely compressional transit time, shear transit time, and bulk density. The new correlation was tested for different cases with different lithology such as calcite, dolomite, and sandstone. It gave good match to the measured data in the laboratory which indicates the accuracy and robustness of this correlation. In addition, it outperformed all correlations from the literature in predicting the static Young's modulus. It will also help in saving time as well as cost because only the available log data are used in the prediction. [ABSTRACT FROM AUTHOR]

The ductile damage in deformed dual-phase steel sheets (DP600) was investigated based on measurements of the degradation of the direction-dependent Young's modulus. The study focuses on the material-induced damage anisotropy in such advanced high-strength steel. The elastic properties in the direction of applied loading of the deformed sheets were determined by measuring the resonance frequency of rectangular samples. The material was investigated in the as-delivered condition and after annealing at 220 C for 48 h. Tensile strains of up to 10% were applied after annealing. Tensile tests were performed in different directions with respect to the rolling direction to determine the evolution of damage in different directions. The comparison of the obtained results with the electron micrographs shows that the damage in the steel sheets occurs in the form of nano and micro damages near the grain boundary and interfaces of phases. The maximum decrease of the Young's modulus in the transverse direction was observed for the largest applied deformation of 10% tensile strain in the transverse direction. An efficient calculation method to obtain information on the distribution of anisotropy in the plane of the sheet was applied. This calculation method relies on an efficient representation of the material's texture. In order to assess the influence of texture, the texture was determined experimentally. [ABSTRACT FROM AUTHOR]

Yarn shooting experiments were conducted to determine the ballistically-relevant, Young's modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted, transversely, by two types of cylindrical steel projectiles at velocities ranging from 150 to 555 m/s: (i) a reverse-fired, fragment simulating projectile (FSP) where the flat rear face impacted the yarn rather than the beveled nose; and (ii) a 'saddle-nosed projectile' having a specially contoured nose imparting circular curvature in the region of impact, but opposite curvature transversely to prevent yarn slippage off the nose. Experimental data consisted of sequential photographic images of the progress of the triangular transverse wave, as well as tensile wave speed measured using spaced, piezo-electric sensors. Yarn Young's modulus, calculated from the tensile wave-speed, varied from 133 GPa at minimal initial tension to 208 GPa at the highest initial tensions. However, varying projectile impact velocity, and thus, the strain jump on impact, had negligible effect on the modulus. Contrary to predictions from the classical Cole-Smith model for 1D yarn impact, the critical velocity for yarn failure differed significantly for the two projectile types, being 18% lower for the flat-faced, reversed FSP projectile compared to the saddle-nosed projectile, which converts to an apparent 25% difference in yarn strength. To explain this difference, a wave-propagation model was developed that incorporates tension wave collision under blunt impact by a flat-faced projectile, in contrast to outward wave propagation in the classical model. Agreement between experiment and model predictions was outstanding across a wide range of initial yarn tensions. However, plots of calculated failure stress versus yarn pre-tension stress resulted in apparent yarn strengths much lower than 3.4 GPa from quasi-static tension tests, although a plot of critical velocity versus initial tension did project to 3.4 GPa at zero velocity. This strength reduction (occurring also in aramid fibers) suggested that transverse fiber distortion and yarn compaction from a compressive shock wave under the projectile results in fiber-on-fiber interference in the emerging transverse wave front, causing a gradient in fiber tensile strains with depth, and strain concentration in fibers nearest the projectile face. A model was developed to illustrate the phenomenon. [ABSTRACT FROM AUTHOR]

In this paper, a new approach is proposed for coalbed methane (CBM) reservoir brittleness index ( BI ) calculations. The BI , as a guide for fracture area selection, is calculated by dynamic elastic parameters (dynamic Young's modulus E d and dynamic Poisson's ratio υ d ) obtained from an amplitude versus offset (AVO) simultaneous inversion. Among the three different classes of CBM reservoirs distinguished on the basis of brittleness in the theoretical part of this study, class I reservoirs with high BI values are identified as preferential target areas for fracturing. Therefore, we derive the AVO approximation equation expressed by E d and υ d first. This allows the direct inversion of the dynamic elastic parameters through the pre-stack AVO simultaneous inversion, which is based on Bayes' theorem. Thereafter, a test model with Gaussian white noise and a through-well seismic profile inversion is used to demonstrate the high reliability of the inversion parameters. Accordingly, the BI of a CBM reservoir section from the Qinshui Basin is calculated using the proposed method and a class I reservoir section detected through brittleness evaluation. From the outcome of this study, we believe the adoption of this new approach could act as a guide and reference for BI calculations and evaluations of CBM reservoirs. [ABSTRACT FROM AUTHOR]

In this study the tropical light hardwood species jelutong (Dyera costulata), terbulan (Endospermum diadenum), batai (Paraserianthes moluccana), rubberwood (Hevea brasiliensis), and pulai (Alstonia pneumatophora) were treated with benzene diazonium salt to improve their dynamic Young’s modulus (Ed), and thermal stability. Benzine diazonium salt reacted with cellulose in wood and produced 2,6-diazocellulose by a coupling reaction, as confirmed by Fourier transform infrared (FTIR) spectroscopy. Values of Ed were calculated from the free-free flexural vibration method and found to increase on treatment. The morphological properties were studied by FTIR and scanning electron microscopy (SEM) and found to be changed. Thermal properties of treated wood samples were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The treated wood samples exhibited an increased thermal stability relative to the untreated wood samples; this increase may be related to the formation of 2, 6-diazo cellulose compound.

This paper describes a method of determining the dynamic Young’s modulus of concrete by measuring the eigenfrequency. In the introduction, reference is made to the findings reported by other researchers in this field. As part of this study, laboratory tests on 24 beam elements (differing in their reinforcement ratios and concrete mixes) were carried out using operational modal analysis. The results of dynamic and static tests carried out on concrete cylinders are compared. Conclusions and recommendations concerning the determination of the dynamic Young’s modulus are formulated. [ABSTRACT FROM AUTHOR]

Objectives Flowable dental composites are used as restorative materials due to their excellent esthetics and rheology. However, they suffer from inferior mechanical properties compared to conventional composites. The aim of this study was to reinforce a flowable dental composite with TiO 2 nanotubes (n-TiO 2 ) and to assess the effect of n-TiO 2 surface modifications on the mechanical properties of the reinforced composite. Methods n-TiO 2 were synthesized using an alkaline hydrothermal process and then functionalized with silane or methacrylic acid (MA). Nanotubes were characterized by scanning and transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Commercially available flowable composite (Filtek™ Supreme Ultra Flowable Restorative, 3M ESPE) was reinforced with varying amounts of nanotubes (0–5 wt%). Flowability of the resulting composites was evaluated using a Gillmore needle method. Dynamic Young's modulus ( E ) was measured using an ultrasonic technique. Fracture toughness ( K Ic ) was assessed using a notchless triangular prism and radiopacity was quantified. Viability of NIH/3T3 fibroblasts was evaluated following incubation on composite specimens for 24 h. Results Electron microscopy revealed a tubular morphology of n-TiO 2 . All reinforced composites exhibited significantly greater values of E than unreinforced composite. Composites reinforced with 3 wt% n-TiO 2 functionalized with MA exhibited the greatest values of E and K Ic . Cytotoxicity assays revealed that reinforced composites were biocompatible. Taken together, flowable composites reinforced with n-TiO 2 exhibited mechanical properties superior to those of unreinforced composite, with minimal effects on flowability and radiopacity. Significance n-TiO 2 -reinforced flowable composites are promising materials for use in dental restorations. [ABSTRACT FROM AUTHOR]

Lightweight metal-matrix composites (MMC) are being applied in many fields such as aerospace and automotive, where detailed knowledge about their elastic and inelastic properties is required to make optimal design of the component. In this study the high-temperature damping capacity and dynamic Young’s modulus of hot-pressed AlSi-based hybrid composites reinforced with silicon carbide particles (SiC p ) and carbon nanotubes (CNTs) were experimentally measured and compared with AlSi–SiC p and AlSi–CNT composites. Results show that by reinforcing AlSi–SiC p with CNTs, the damping capacity is improved without reducing mechanical properties. The highest damping capacity value was attained by AlSi–(CNT–SiC p ) hybrid composite, for all the studied frequencies and temperatures, followed by AlSi–SiC p and AlSi–CNT composites. The possible damping mechanisms for all these produced composites are presented and discussed. Unlike to damping capacity, the dynamic Young’s modulus shows no substantial changes after adding CNTs to AlSi–SiC p . Results show that by using a proper combination of materials (including different types of reinforcements), scales (nano- and micro-sized reinforcements) and manufacturing processes, the design of a material with required damping capacity and mechanical properties is possible. [ABSTRACT FROM AUTHOR]

Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted, transversely, by two types of cylindrical steel projectiles at velocities ranging from 150 to 555 m/s: (i) a reverse-fired, fragment simulating projectile (FSP) where the flat rear face impacted the yarn rather than the beveled nose; and (ii) a ‘saddle-nosed projectile’ having a specially contoured nose imparting circular curvature in the region of impact, but opposite curvature transversely to prevent yarn slippage off the nose. Experimental data consisted of sequential photographic images of the progress of the triangular transverse wave, as well as tensile wave speed measured using spaced, piezo-electric sensors. Yarn Young’s modulus, calculated from the tensile wave-speed, varied from 133 GPa at minimal initial tension to 208 GPa at the highest initial tensions. However, varying projectile impact velocity, and thus, the strain jump on impact, had negligible effect on the modulus. Contrary to predictions from the classical Cole-Smith model for 1D yarn impact, the critical velocity for yarn failure differed significantly for the two projectile types, being 18% lower for the flat-faced, reversed FSP projectile compared to the saddle-nosed projectile, which converts to an apparent 25% difference in yarn strength. To explain this difference, a wave-propagation model was developed that incorporates tension wave collision under blunt impact by a flat-faced projectile, in contrast to outward wave propagation in the classical model. Agreement between experiment and model predictions was outstanding across a wide range of initial yarn tensions. However, plots of calculated failure stress versus yarn pre-tension stress resulted in apparent yarn strengths much lower than 3.4 GPa from quasi-static tension tests, although a plot of critical velocity versus initial tension did project to 3.4 GPa at zero velocity. This strength reduction (occurring also in aramid fibers) suggested that transverse fiber distortion and yarn compaction from a compressive shock wave under the projectile results in fiber-on-fiber interference in the emerging transverse wave front, causing a gradient in fiber tensile strains with depth, and strain concentration in fibers nearest the projectile face. A model was developed to illustrate the phenomenon.

Intact and vulnerable speleothems can be investigated in situ to estimate an upper limit of prehistoric peak ground acceleration. It is possible to say that intact speleothem was not loaded by horizontal acceleration higher than the value of horizontal acceleration resulting in failure, which is assessed by theoretical calculations. Mechanical properties of broken speleothems originating in the same cave are considered for this calculation. In the present paper, determination of the dynamic Young's modulus of broken speleothems originated in Baradla-Domica cave system (Northern Hungary and Southern Slovakia) is presented. The dynamic Young's modulus can be calculated based on P and S-wave velocities and bulk density of tested specimens. Two different approaches to determination of bulk density of irregular speleothem specimens are presented - determination of bulk density by standard "Water displacement method" and by "X-Ray Computed Tomography". [ABSTRACT FROM AUTHOR]

In this paper, the large-amplitude (geometrically nonlinear) vibrations of rotating, laminated composite circular cylindrical shells subjected to radial harmonic excitation in the neighborhood of the lowest resonances are investigated. Nonlinearities due to large-amplitude shell motion are considered using the Donnell's nonlinear shallow-shell theory, with account taken of the effect of viscous structure damping. The dynamic Young's modulus which varies with vibrational frequency of the laminated composite shell is considered. An improved nonlinear model, which needs not to introduce the Airy stress function, is employed to study the nonlinear forced vibrations of the present shells. The system is discretized by Galerkin's method while a model involving two degrees of freedom, allowing for the traveling wave response of the shell, is adopted. The method of harmonic balance is applied to study the forced vibration responses of the two-degrees-of-freedom system. The stability of analytical steady-state solutions is analyzed. Results obtained with analytical method are compared with numerical simulation. The agreement between them bespeaks the validity of the method developed in this paper. The effects of rotating speed and some other parameters on the nonlinear dynamic response of the system are also investigated. [ABSTRACT FROM AUTHOR]

Eucalyptus camaldulensis Dehnh. is extensively planted in Thailand to produce wood chips used as raw material for pulp and paper. To promote the utilization of the wood from plantation-grown E. camaldulensis for solid lumber, stress-wave velocity of trees and dynamic Young’s modulus of logs were investigated for 4-year-old trees of eight half-sib families selected for pulpwood production on the basis of the growth characteristics in the previous tree breeding program. For the eight families, the mean stem diameter at 1.3 m above ground level and mean tree height were 7.6 cm and 11.9 m, respectively. The mean stress-wave velocity of eight families was 3.45 km/s. Dynamic Young’s modulus of logs ranged from 7.88 to 17.64 GPa, and the mean value for the eight families was 11.72 GPa. Stress-wave velocity of trees was significantly correlated with dynamic Young’s modulus of logs, suggesting that dynamic Young’s modulus of wood can be evaluated nondestructively by stress-wave velocity of trees. Significant differences in stress-wave velocity and dynamic Young’s modulus of logs were obtained among families. Thus, to promote the utilization of E.camaldulensis wood for solid lumber production, selection of trees with high Young’s modulus should be applied to trees already selected for the growth characteristics in the previous tree breeding program. [ABSTRACT FROM AUTHOR]

Objectives: To synthesize and characterize machinable, bioactive glass-ceramics (GCs) suitable for dental implant applications. Methods: A glass in the SiO2–Al2O3–CaO–CaF2–K2O–B2O3–La2O3 system was synthesized by wet chemical methods, followed by calcination, melting and quenching. Crystallization kinetics were determined by differential thermal analysis (DTA). GC discs were produced by cold pressing of the glass powder and sintered using schedules determined by DTA. The crystalline phases and microstructure of GC samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Dynamic Young's modulus (E), true hardness (H o), fracture toughness (K IC) and brittleness index (BI) were evaluated. Bioactivity was studied by examining the formation of hydroxyapatite (HA) on the GC surfaces after soaking in simulated body fluid (SBF). Attachment and proliferation of MC3T3-E1 osteoblastic cells were assessed in vitro. Results: Miserite [KCa5(Si2O7)(Si6O15)(OH)F] was the main crystalline phase of the GC with additional secondary phases. Microstructural studies revealed interlocking lath-like crystalline morphology. E, H o, and K IC values for the GCs were 96±3GPa, 5.27±0.26GPa and 4.77±0.27MPam0.5, respectively. The BI was found to be 1.11±0.05μm−0.5, indicating outstanding machinability. An HA surface layer was formed on the GC surfaces when soaked in SBF, indicating potential bioactivity. MC3T3-E1 cells exhibited attachment, spreading and proliferation on GC surfaces, demonstrating excellent biocompatibility. Significance: We present a novel approach for the synthesis of miserite GC with the physical and biological properties required for non-metallic dental implant applications. [ABSTRACT FROM AUTHOR]

Abstract: Porous samples of commercially pure titanium (CP Ti) were fabricated by using sodium chloride (NaCl) as space-holder with percentages between 40 and 70vol%. The dissolution of NaCl in distilled water, the structural integrity of samples and the reproducibility of the procedure were studied as a step prior to sintering. All these parameters were evaluated in terms of the compaction pressure, temperature and agitation of water, and dissolution time. The characterization of samples included density, porosity and dynamic Young''s modulus. The results indicate that the most efficient lixiviation, according to the desired balance of properties, was by immersion in hot water, without agitation and for prolonged cycles of immersion time. [Copyright &y& Elsevier]

Abstract: Thermal effects on the vibrational behaviors and dynamic Young’s modulus of single-walled carbon nanotubes (SWCNTs) are investigated through both constant temperature molecular dynamics (MD) simulation and modified molecular structural mechanics (MMSM) modeling. The MD simulation incorporates a modified Nosé-Hoover thermostat model to control the system temperature. In the MMSM modeling, the covalent and nonbonded interactions between carbon atom pairs are modeled with the second generation force field and the Lennard–Jones potential, respectively, where the covalent bonds are treated as Euler–Bernoulli beam and the temperature-dependent bond length and angle are determined through the Badger’s rule and MD simulation. The results derived from these two approaches are compared with each other and the published theoretical and experimental data. Results show that the dynamic Young’s modulus of the SWCNTs tends to be smaller than the published static one obtained from uniaxial tensile tests, and their natural frequency and dynamic Young’s modulus would decrease with increasing temperature. Moreover, a comparable frequency ratio of the first two flexural modes is achieved by these two approaches. The frequency ratio is highly dependent on their aspect ratio but independent of temperature, and would converge to the literature experimental data (about 6.1–6.2) as the aspect ratio becomes very large. [Copyright &y& Elsevier]

Abstract: An experimental study was performed to evaluate the delamination in the concrete using ultrasonic pulse velocity (UPV) method. Two slab specimens of 150-mm and 300-mm thicknesses consisted of delaminations of varying sizes at quarter depths. Using indirect transmission method, the transit times of longitudinal and Rayleigh waves were measured to determine the dynamic Young’s modulus and Poisson’s ratio of the concrete. The static modulus was also measured and compared. The location and size of the delaminations in the slab were evaluated from the direct transmission method. The diffraction of the longitudinal wave at delaminations decreased the wave velocity and a qualitative correlation was established between the transit time of the UPV signal and the size of the delamination. [Copyright &y& Elsevier]

Various tropical wood species are abundantly available in Southeast Asia, especially in Borneo Island. In this study, selected tropical wood species, Eugenia spp., Artocarpus rigidus, Artocarpus elasticus, Koompassia malaccensis and Xylopia spp., were chemically treated with sodium meta periodate to convert them into wood polymer composites (WPCs). Manufactured WPCs were characterised using microstructural analysis (Fourier transform infrared spectroscopy and SEM) and dynamic Young's modulus measurement. The dynamic Young's modulus was calculated using vibrational testing E d and dynamic mechanical thermal analysis E′. Spectroscopic analysis results indicated the absorption band of raw wood at 1635 cm-1 due to carbonyl stretching and WPCs showed increased absorption band near 1718 cm-1. The manufactured WPCs yielded higher Young's modulus compared with raw woods. A. elasticus WPC had the highest Young's modulus compared with the other composites. [ABSTRACT FROM AUTHOR]

Dynamic Young's modulus (Ed) of selected tropical wood species, namely Dyera polyphylla, Endospermum diadenum, Cratoxylum arborecens, Alstonia pneumatophora, Macaranga gigantea and Commersonia bartramia, used for the study was measured using the free-free flexural vibration method. Young's modulus from three point bending (E3pb) and compression parallel to grain (Ecp) was also studied. The results show that the relationship between Ed and E3pb for all wood species is very significant with the mean value of Ed consistently larger than or sometime equal to E3pb. Surprisingly, the relationship between Ed and Ecp is not significant except for Alstonia pneumatophora. The dynamic mechanical thermal properties were also investigated using the dynamic mechanical thermal analyser (DMTA). The results showed that the storage modulus of the wood species at -90°C is in the range of 1.48-4.09 GPa with a glass transition temperature ranging from 50 to 70°C. [ABSTRACT FROM AUTHOR]

• It is possible to pre-crack CTBM specimens in laboratory with a mechanical hammer. • Dynamic Young's modulus measurements through resonance testing are a great non destructive tool to evaluate the effect of the pre-cracking. • The pre-cracking of CTBM specimens does not change much the rate of water evaporation. • Pre-cracked CTBM specimens have slightly higher mechanical strengths than CTBM specimens without pre-cracking as soon as a few days after the pre-cracking. In this paper, the effects of pre-cracking on the early-age mechanical properties of a cement-treated base material (CTBM) were studied. To do so, CTBM with 4% cement by mass of dry granular material were mixed in laboratory in order to make cylindrical specimens. Half of the specimens were pre-cracked (PC) with a mechanical impact hammer after a two days moist curing process. The immediate effect of the pre-cracking (PC) was evaluated with dynamic Young's modulus measurements performed just before (B) and right after (A) the PC. Then, tests were performed in laboratory to compare the early-age mechanical properties (dynamic Young's modulus, compressive and indirect tensile strengths) of the specimens without pre-cracking (WPC) and with pre-cracking (PC). As early as five days after the pre-cracking, the dynamic Young's modulus, and the compressive and indirect tensile strengths of the PC specimens are higher than those of the WPC specimens. In addition, the pre-cracking seems to accelerate the hydration process and water evaporation. The results of this study therefore suggest that the pre-cracking only has a positive effect on the early increase of the mechanical strengths. [ABSTRACT FROM AUTHOR]

Abstract: The effects of Ta and Hf on the dynamic Young''s moduli and tensile properties of Ti–Ta and Ti–Hf alloys for biomedical applications are comparatively studied in this paper. It is found that with increasing Hf content, the dynamic Young''s modulus of the Ti–Hf alloy gently decreases and its tensile strength keeps on increasing. In contrast, with increasing Ta content, the dynamic Young''s modulus of the Ti–Ta alloys first decreases, reaches a minimum value of 69GPa and then increases. In parallel, the tensile strength first increases, reaches a maximum value of 587MPa, and then slightly decreases. It is shown that the addition of Hf has a slight influence on the dynamic Young''s modulus and a strong influence on the tensile properties of the Ti–Hf alloy, while an increase of Ta content has a strong effect on both the dynamic Young''s modulus and tensile properties of the Ti–Ta alloy. [Copyright &y& Elsevier]

The peritectic alloy Sn–10Sb, was chosen as one of the lead-free solder alloys to be subjected to many studies. Bi atoms were added to this alloy in the range of 1–3 wt%. The experimental results obtained from this study show a complete solubility of Bi atoms when added by 2 wt%. More additions of Bi tend to increase the formation of the intermetallic compound SnSb by reducing the precipitations of Sb as a single phase. This intermetallic compound with the precipitation of Bi as a third phase tends to improve the mechanical properties of this alloy. [ABSTRACT FROM AUTHOR]

An attempt has been made to measure the temperature dependence of dynamic Young’s modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was employed using a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young’s modulus and internal friction were measured over a temperature range of 298 to 873 K at very low frequencies of 0.1, 0.05, and 0.01 Hz. One internal friction peak was observed over the ranges 450 to 700 K, together with marked decreases in the dynamic Young’s modulus in the same temperature range. From a quantitative analysis of the experimental data with the relaxation strength, relaxation time, and activation energy, it is concluded that the peak phenomenon is due to grain-boundary sliding relaxation. [ABSTRACT FROM AUTHOR]