Different Moduli Of Elasticity Research Articles

Investigating Vibration Characteristics of Cross-Laminated Timber Panels Made from Fast-Grown Plantation Eucalyptus nitens under Different Support Conditions

The mechanical properties of fibre-managed Eucalyptus nitens (E. nitens) cross-laminated timber (CLT) have previously been extensively studied, proving the material to be structurally safe and reliable. However, the vibration performance of CLT manufactured from this relative new construction species is not yet fully understood, especially under different support conditions. In this study, three types of support conditions, including roller–roller, bearer–bearer and clamp–bearer support conditions, were examined under vibration impulse-response testing performed using a simple but effective and repeatable excitation method consisting of a basketball dropped from a known height and an accelerometer. Six three-ply E. nitens CLT panels considered to have different moduli of elasticity in different layers and one strength-class C24 spruce CLT as a controlled reference were included in this study. The results suggest that the fundamental frequency values can effectively reflect the inherent characteristics of CLT panels (bending stiffness and density); however, no obvious relationship was observed between damping ratios and these inherent properties. The values of frequency constant λ1 were determined to analyse the effect of different support conditions on the values of fundamental frequency. The average values of λ1 for the roller–roller (9.6) and bearer–bearer (10.1) supports align with the theoretical values (9.87) for simply support (S-S) conditions. However, when clamping loads were applied at one edge of the bearer support, the average values of λ1 increased up to 10.8 but remained far below the theoretical values for clamped–pinned (C-S) support (15.4).

A ELASTO-PLASTIC CONSTITUTIVE MODEL BASED ON CHABOCHE KINEMATIC HARDENING OF ALUMINUM ALLOY 7050-T7451

The elasto-plastic behavior of the aluminum alloy 7050-T7451 subjected to cyclic loading was investigated and modeled. The objective of this work is to improve the constitutive model of Chaboche with a special emphasis in the compression. In the proposed model, the part under tension of the stress-strain curve in the stable hysteresis cycle is modeled separately from the compressed one, where it is considered that they have different Modulus of Elasticity. The work includes both simulation and experimental data, and they are compared to each other. The values were collected experimentally by the application of symmetric cyclic strain-driven loading in the strain range between 0.75% and 2.25%. The experimental results were used to calculate the parameters of the constitutive model in a MATLAB® software. The responses obtained with the proposed model have greater adherence to the experimental results than those obtained with the Chaboche model.

Determining the residual service life of polymer-modified asphalt concrete pavement on road bridges

The object of research is the asphalt pavement of road bridges. Its residual period was assessed taking into account the joint effect of the ambient temperature and vehicles. It has been established that a set of negative factors affects the reduction of the service life (residual resource) of asphalt pavement on bridges. These include different modulus of elasticity of reinforced concrete base and asphalt pavement and the difference in coefficients of linear thermal expansion. As well as loads from the wheels of vehicles, temperature fluctuations, alternating freezing-thawing of water in pores and damaged places. It was found that one of the reasons for reducing the residual life of asphalt pavement on reinforced concrete road bridges is the insufficient study and use of polymers in order to adjust the properties of asphalt concrete. Taking into account the joint influence of temperature and transport in assessing the crack resistance of asphalt pavement on reinforced concrete road bridges would allow a more objective assessment of the residual life of such coatings and their service life. Arrangement of asphalt pavement with improved properties, due to polymeric latex, could increase its residual life. This, in turn, would lead to a reduction in costs for the repair and maintenance of not only asphalt pavement but also the road bridge as a whole

In silico fatigue performance of molars restored with full crowns under alternating cyclic loadings

ObjectiveIn this study, a preclinical approach was used to analyze and directly compare the fatigue performance (fatigue life and damage percentage) and maximum principal stresses (Max. Ps) of prepared models treated with different materials and geometric parameters. MethodsFour groups of preparative parameters (crown width, crown length, degree of polymerization and material) were selected, each with five variables. An alternating cyclic occlusal load with an amplitude of 300 N was applied to the ball part along the longitudinal axis. The fatigue properties of the preparations and Max.Ps were analyzed. ResultsA shoulder width of 0.8 mm, a shoulder height offset of 0.2 mm, a degree of polymerization of 5°, and a crown material of ZC resulted in the smallest percentage of damage. In contrast, the effect of different modulus of elasticity (MOE) on Max.Ps was not significant (p = 0.609). ConclusionThe results suggest that the selection of larger modulus of elasticity MOE and larger Poisson's ratio material's, preparation of larger shoulder widths within safety, reasonable increase in crown length, and selection of larger degree of polymerization are favorable methods to protect the preparation.

Stress distribution and fracture resistance of green reprocessed polyetheretherketone (PEEK) single implant crown restorations compared to unreprocessed PEEK and Zirconia: an in-vitro study

BackgroundIt is unclear which crown materials are optimum to disperse the generated stresses around dental implants. The objective of this study is to assess stress distribution and fracture resistance of green reprocessed Polyetheretherketone (PEEK) in comparison to un-reprocessed PEEK and zirconia single implant crown restorations.MethodsTwenty crowns (n = 20) were obtained, five from zirconia and fifteen from pressed PEEK that were subdivided into 3 groups of five specimens each (n = 5) according to weight% of reprocessed material used. A 100% new PEEK was used for the first group, 50% new and 50% reprocessed PEEK were used for the second group, and a 100% reprocessed PEEK was used for the third group. Epoxy resin model with dental implant in the second mandibular premolar was constructed with strain gauges located mesially and distally to the implant to record strain while a load of 100 N was applied with 0.5 mm/min then specimens of all groups were vertically loaded till failure in a universal testing machine at cross head speed 1 mm/min. Data was statistically analyzed by using One-way Analysis of Variance (ANOVA) followed by Post-hoc test when ANOVA test is significant.ResultsNo significant difference between strain values of tested groups (p = 0.174) was noticed. However, a significant difference between fracture resistance values was noticed where the zirconia group recorded a significantly higher value (p < 0.001).ConclusionsImplant restorative materials with different moduli of elasticity have similar effects regarding stresses distributed through dental implant and their surrounding bone. Reprocessed PEEK implant restorations transmit similar stresses to dental implant and surrounding bone as non-reprocessed PEEK and zirconia restorations. Zirconia failed at higher load values than all tested PEEK restorations but all can be safely used in the posterior area as crown restorations for single implants.Clinical relevanceApplying “green dentistry” principles may extend to include reprocessing of pressed PEEK restorative materials without affecting the material’s shock absorption properties.

Application of the Variational Method to the Large Deformation Problem of Thin Cylindrical Shells with Different Moduli in Tension and Compression

In this study, the variational method concerning displacement components is applied to solve the large deformation problem of a thin cylindrical shell with its four sides fully fixed and under uniformly distributed loads, in which the material that constitutes the shell has a bimodular effect, in comparison to traditional materials, that is, the material will present different moduli of elasticity when it is in tension and compression. For the purpose of the use of the displacement variational method, the physical equations on the bimodular material model and the geometrical equation under large deformation are derived first. Thereafter, the total strain potential energy is expressed in terms of the displacement component, thus bringing the possibilities for the classical Ritz method. Finally, the relationship between load and central deflection is obtained, which is validated with the numerical simulation, and the jumping phenomenon of thin cylindrical shell with a bimodular effect is analyzed. The results indicate that the bimodular effect will change the stiffness of the shell, thus resulting in the corresponding change in the deformation magnitude. When the shell is relatively thin, the bimodular effect will influence the occurrence of the jumping phenomenon of the cylindrical shell.

Behavior of Cross-Laminated Timber Panels Made from Fibre-Managed Eucalyptus nitens under Short-Term Serviceability Loads

In this study, the preliminary serviceability performance of cross-laminated timber (CLT) panels constructed from fibre-managed Eucalyptus nitens (E. nitens) was investigated via bending and vibration tests. Linear four-point bending tests were performed to determine the stiffness and deflection of all CLT panels under serviceability loads. The dynamic response of CLT panels was tested using a basketball and an accelerometer. The fundamental natural frequencies of all tested panels were above the minimum frequency limit (8 Hz) when extrapolated to spans of up to 4.4 m. The configurations of E. nitens CLT panels were based on different modulus of elasticity (MOE) values for each board. Using higher MOE timber boards as the top and bottom layers can significantly increase the serviceability performance of both bending and vibration tests. The same experiments were carried out on two CLT panels made of strength class C24 Spruce-Pine-Fir to compare the serviceability performance of E. nitens CLT. The results demonstrated that E. nitens is a reliable resource for CLT manufacturing, and exhibits better serviceability performance compared to Spruce CLT. This provides more sustainable options for a species traditionally destined for pulp.

Contact Bending Problem for a Multilayer Composite Plate with Allowance for Different Moduli of Elasticity in Tension and Compression

Contact Bending Problem for a Multilayer Composite Plate with Allowance for Different Moduli of Elasticity in Tension and Compression

Microstructure and Mechanical Properties of Ti-25Nb-4Ta-8Sn Alloy Prepared by Spark Plasma Sintering

As the commercially most-used Ti-6Al-4V alloy has a different modulus of elasticity compared to the modulus of elasticity of bone and contains allergenic elements, β-Ti alloy could be a suitable substitution in orthopedics. The spark plasma sintering (SPS) method is feasible for the preparation of materials, with very low porosity and fine-grained structure, leading to higher mechanical properties. In this study, we prepared quaternary Ti-25Nb-4Ta-8Sn alloy using the spark plasma sintering method. The material was also heat-treated in order to homogenize the structure and compare the microstructure and properties in as-sintered and annealed states. The SPS sample had a modulus of elasticity of about 63 ± 1 GPa, which, after annealing, increased to the value of 73 ± 1 GPa. The tensile yield strength (TYS) of the SPS sample was 730 ± 52 MPa, ultimate tensile strength (UTS) 764 ± 10 MPa, and ductility 22 ± 9%. Annealed samples reached higher values of TYS and UTS (831 ± 60 MPa and 954 ± 48 MPa), but the ductility decreased to the value of 3 ± 1%. The obtained results are discussed considering the observed microstructure of the alloy.

Механические свойства регенерата зоны перелома бедренной кости при применении имплантатов с различным модулем упругости

Проведено экспериментальное исследование на бедренных костях кроликов породы шиншилла. Бедренные кости брали из 4 экспериментальных групп наблюдения: контрольной группы, в которой оперативное вмешательство не проводилось, и трех исследуемых групп. Все кролики опытных групп получали в подвертельной области перелом с последующим металлоостеосинтезом металлическими стержнями. Животным второй группы был выполнен металлоостеосинтез стержнем из нержавеющей стали (316L), третьей — из титано-ванадиевого (ВТ-6) и четвертой — из циркониево-титанового сплава (Zr-Ti). Животных выводили из эксперимента через 90 суток после консолидации перелома бедренной кости. Определяли механические характеристики костей на растяжение и сжатие.Установлено, что биомеханические показатели костей на растяжение уступают подобным показателям при сжатии, кости с наличием металлофиксаторов имеют большую прочность в зоне сросшегося перелома, чем кости контрольной группы. При исследовании работы костного регенерата на растяжение и сжатие наилучшие результаты прочности определены в образцах костей с наличием металлофиксатора из β-Zr-Ti-сплава. Проведенное исследование доказывает целесообразность разработки и внедрения в клиническую практику травматологов-ортопедов имплантатов на основе низкомодульного β-Zr-Ti-сплава, что позволит улучшить результаты лечения переломов длинных костей и уменьшить процент послеоперационных осложнений.

Exploring the variability in elastic properties of roots in Alpine tree species

Quantifying the soil reinforcement provided by roots is essential for assessing the contribution of forests to reducing shallow landslide susceptibility. Many soil-root models were developed in the literature: from standard single root model to fibre bundle model. The input parameters of all models are the geometry of roots (diameter and length) and the biomechanical properties (maximum tensile force and elastic modulus). This study aims to investigate the elastic properties estimated by the stress-strain curves measured during tensile tests. A standard procedure detected two different moduli of elasticity: one due to the root tortuosity, and the other due to the woody fibres of roots. Based on a large dataset of tensile tests on different Alpine tree species, the relationships between elastic modulus and root diameter was estimated for each series. Further, the interspecific and intraspecific variability in such relationships was investigated by a statistical analysis. The results showed more intraspecific differences in the elastic modulus vs. root diameter relationships compared to the interspecific ones. This outcome could be an important criterion of discrimination to explain the variability of the elastic properties and to provide representative biomechanical properties for specific environmental conditions.

Impact of modulus of elasticity of silicone hydrogel contact lenses on meibomian glands morphology and function

ABSTRACT Clinical relevance: It is important to investigate the effect of modulus of silicone hydrogel contact lens on meibomian glands. Evaluating meibomian gland health and function in follow-up appointments should be considered, with the option of changing lens modulus. Background: To evaluate and compare the effect of modulus of elasticity of silicone hydrogel contact lenses on morphological and functional parameters of the meibomian glands. Methods: A prospective study was conducted on soft silicone hydrogel contact lens wearers of different modulus of elasticity and age and gender-matched controls. Morphological and functional parameters were assessed along with standard patient evaluation of the eye dryness questionnaire. Results: A statistically significant difference was noted in meibomian gland loss in the upper lid (percent) between the low modulus (18.23 ± 6.63) and high modulus group (27.40 ± 10.21) (p < 0.001) and between high modulus (27.40 ± 10.21) and non-contact lens wearers (19.57 ± 7.65) (p = 0.001). The current study reported significantly higher total meiboscore grading in the high modulus group 3 (2-3) compared to the low modulus 2(2-3) (p = 0.007) and non-contact lens wearing groups 2 (2-3) (p = 0.012). Meibum quality was significantly compromised in the high modulus group 1 (0-1) compared to the low modulus 0 (0-0.75) group (p = 0.01). Standard patient evaluation of the eye dryness questionnaire was found to be significantly higher (p = 0.01) in high modulus 4 (2-8) compared to low modulus wearers 2 (2-4). A significant difference was noted (p < 0.001) in corneal staining grading only between high modulus 0 (0-1) and non-contact lens wearers 0 (0-0) group. A positive correlation was noted in the low modulus group between total meiboscore and meibomian gland expressibility (Rs = +0.69, p < 0.001) and also noted between standard patient evaluation of the eye dryness questionnaire scoring and meibomian gland expressibility (Rs = +0.45, p = 0.012) in the high modulus group. Conclusion: Higher modulus of elasticity of silicone hydrogel contact lens may influence meibomian gland morphology and function over a period of contact lens wear.

Influence of the Cross-Sectional Shape of a Reinforced Bimodular Beam on the Stress-Strain State in a Transverse Impact

The paper considers the stress-strain state of a reinforced concrete beam, as a bimodular material, under the action of an impact. The behavior of bimodular concretes with different moduli of elasticity in tension and compression has not been studied enough. At the same time, taking into account the bimodularity of concrete makes it possible to design a more economical structure, especially for dynamic load. In this article, the impact is considered as an absolutely plastic impact of an absolutely rigid body on an elastic system. The stress state is investigated for beams of rectangular, T-section and I-sections, and is compared with and without the bimodularity of reinforced concrete. The analysis of the dependence of the stress state on the shape, cross-sectional dimensions, and the location of reinforcing bars in the compressed and tensioned zones was carried out for lightweight concrete (Et &lt; Ec) and for heavy concrete (Et &gt; Ec) under the action of shock load with and without regard to the mass of the beam. The numerical study shows that taking into account the mass of the beam upon impact significantly decreases the magnitude of the normal stresses in both the tensioned and compressed zones. Beams of rectangular cross-section have the highest load-bearing capacity when the cross-section height is equal for both light and heavy concrete. An increase in the size of the flange of the I-beam in the stretched zone leads to a sharp decrease in normal tensile stresses and a slight increase in normal compressive stresses. The proposed engineering method makes it possible to numerically study the effect on the stress-strain state of a beam under the action of a concentrated impact of various geometric characteristics of the cross-section, bimodularity of the material, size, number and location of reinforcement.

Structural, elastic, optical and γ-ray shielding behavior of Dy3+ ions doped heavy metal incorporated borate glasses

The effect of modifier ions in different basis have been analyzed through a new series of heavy metals incorporated borate based glasses 39H3BO3+30PbO+20MO+10Bi2O3 +1Dy2O3 (where M=Ca,Sr,Ba,Na and K) which are synthesized following melt quenching technique for radiation screening applications. The potentiality of glasses to withstand the penetration of fast moving neutrons is checked by various studies. Functional groups are identified through different stretching and bending modes of vibrations within the glass membrane through FTIR spectral analysis. In addition to that, other structural properties like Boron-Boron distance (dB−B), molar volume of oxygen (Vo), Oxygen Packing Density (OPD), optical basicity (Λth) and Bond density (nb) are calculated theoretically. The bonding nature (β) and nephelauxetic ratio (δ) values reveals that the glasses possess more of ionic linkages. The high density value exhibited by the Bismuth lead borate glasses indicates their capability to act as a good shielding material in reactors emitting hazardous radiation. Different moduli of elasticity (E, K, G, σ) values for the present glasses are calculated and the results reveal the enhancement in shielding performances when compared to other existing glasses and a comparative study is made on it. Optical studies are carried out and the absorption of Dy3+ions to different energy levels is observed and optical band gap (Eopt) values of the synthesized glasses are calculated along with the Urbach energy (ΔE) values. Radiation shielding properties of the produced glasses were investigated in terms of the mass attenuation coefficients (µm), transmission fraction (T), half value layer (HVL) and effective atomic number (Zeff) parameters. The results attained in the shielding study indicated that glass specimen with M = Ba exhibits enhanced shielding behavior as Ba owns high atomic number (Z) compared to other elements. Glass specimen with M = Na shows the poorest shielding characteristics due to the low Z of Na.

Piezoelectric Actuators for Tactile and Elasticity Sensing

Piezoelectric actuators have achieved remarkable progress in many fields, being able to generate forces or displacements to perform scanning, tuning, manipulating, tactile sensing or delivering functions. In this work, two piezoelectric PZT (lead zirconate titanate) bimorph actuators, with different tip contact materials, were applied as tactile sensors to estimate the modulus of elasticity, or Young’s modulus, of low-stiffness materials. The actuators were chosen to work in resonance, taking advantage of a relatively low resonant frequency of the out-of-plane vibrational modes, associated with a convenient compliance, proven by optical and electrical characterization. Optical measurements performed with a scanning laser vibrometer confirmed that the displacement per applied voltage was around 437 nm/V for the resonator with the lower mass tip. In order to determine the modulus of elasticity of the sensed materials, the stiffness coefficient of the resonator was first calibrated against a force sensor, obtaining a value of 1565 ± 138 N/m. The actuators were mounted in a positioning stage to allow approximation and contact of the sensor tip with a set of target materials. Electrical measurements were performed using the resonator as part of an oscillator circuit, and the modulus of elasticity of the sample was derived from the contact resonant frequency curve of the cantilever–sample system. The resulting sensor is an effective, low-cost and non-destructive solution compared to atomic force microscopy (AFM) techniques. Materials with different modulus of elasticity were tested and the results compared to values reported in the literature.

Effects of the beam cross-section geometry on the lengthwise fracture of inhomogeneous beams

The present paper analyzes the effects of the beam cross-section on the lengthwise fracture behaviour of inhomogeneous beam configurations in terms of the strain energy release rate by applying linear-elastic fracture mechanics. The material is continuously inhomogeneous along height and length of the beams. A methodology for calculation of the strain energy release rate is developed and used for analyzing lengthwise fracture of a simply supported inhomogeneous beam loaded by one vertical force applied at the lower crack arm. The solutions to the strain energy release rate are verified by using the compliance method. Four beam cross-section geometries (isosceles triangle, antiparallelogram, T-shape and circle) and their effects on the lengthwise fracture behaviour are considered in detail. The lengthwise fracture behaviour of the inhomogeneous beam is analyzed also for the case when material has different moduli of elasticity in tension and compression. The results reported in the present paper can be applied in fracture mechanics based design of inhomogeneous structural members and components.

Correlation Between Ocular Comfort and Vision Quality of Three Daily Disposable Soft Toric Contact Lenses with Different Moduli of Elasticity

Purpose: Studies have shown that when vision quality is low, ocular comfort decreases. In addition, silicone hydrogel (SiHy) contact lenses typically have a higher modulus of elasticity than their hydrogel counterparts which can also affect comfort. Therefore, it is of interest to investigate if comfort is correlated to vision quality irrespective of modulus. This study investigated the relationship between comfort and vision quality with three daily disposable (DD) soft toric CLs (two hydrogel and one SiHy) with a range of modulus values.

Novel hollow fiber sandwich composite post system: mechanical characteristics.

There is currently no consensus on the optimal post system to provide effective long-term results. We used an engineering approach to investigate the mechanical properties of a sandwich hollow carbon fiber post in synergy with a new bonding technique. We studied two systems - a sandwich fiber hollow post (Techole®, Isasan, Como, Italy) composed of carbon fiber incorporated in a Dpp-MOR resin mix and a traditional non-hollow post (Tech 2000®, Isasan, Como, Italy). A bi-component composite (Clearfil Core®, Kuraray, New York, NY, USA) (2.2 gcm3, 12.3 GPa) and a dual cure composite with lower density and modulus of elasticity (Clearfil DC Core®, Kuraray, New York, NY, USA) (2.0 gcm3, 10.0 GPa) were also used into hollow posts. Results from three-point bending test (N.=81), compression test (N.=78) and cut test (N.=81) were achieved. In the three-point bending test there were significant differences in flexibility/bending when sandwich fiber hollow posts were filled with composite of different modulus of elasticity. Hollow sandwich posts showed also significant (P=0.000) better resistance to compression and cutting than solid posts, independently of the type of composite. Moreover, hollow posts filled plus composite with a modulus of elasticity of 12.3 GPa showed significant (P=0.000) improved resistance parameters rather than hollow posts filled with a composite of 10.0 GPa. The study confirms the favorable mechanical properties of the hollow sandwich fiber post system (Techole®) and the synergistic efficacy when used in combination with the composite Clearfil DC Core® (10.0 GPa) and, especially, Clearfil Core® (12.3 GPa).

Numerical investigation of stress analysis of composite materials with various elasicity

Composite materials have a widespread use in engineering applications and modern structures because of the qualified physical and mechanical properties. Therefore, study the structures of composite material becomes attractive and reserchers to obtain novel materials that qualified environment updates. In this study, the displacements and stress analysis of two-dimensional composite materials have different modulus of elasticity and mechanical properties have discussed. Finite difference method was used in this study where the model solved using Fortran 90. The results show that, the change in elasticity in one of the layers has significant effects on the displacements and stresses distributions of the layers of the composite. In addition, the influence of passion’s ratio with elasticity at the same time is discussed. They have important effect on the stress analysis. The results were in the acceptable limit which confirms the reliability of the finite difference method.

Composite vs. ionomer vs. mixed restoration of wedge-shaped dental cervical lesions: Marginal quality relative to eccentric occlusal loading

Dental cervical restorations may be impacted by resultants of occlusal loads that may have already contributed to the development of the lesion and should rely on materials’ favorable properties to bear the stresses. The marginal quality of cervical restorations made with materials of different moduli of elasticity in essence, isolated, or in combination, was evaluated relative to eccentric occlusal loading. Cervical wedge-shaped cavities, prepared in extracted premolars, were restored with a composite resin (CR), a restorative ionomer (GIC), or the composite in combination with a lining ionomer (Mixed restoration: M). Half of the teeth in each group were subjected to eccentric occlusal loading (eol; 150 N / 106 cycles / 2.5 Hz; CReol / GICeol / Meol, n = 10), and the others were stored in 37 °C distilled water (Control: c; CRc / GICc / Mc, n = 10). A fluorescein-modified adhesive favored delimitation of formed gaps, which were evaluated by confocal laser scanning microscopy regarding their presence, location related to the cavity walls, and width and depth (µm), at a 5% significance level. From a comprehensive perspective, neither the loading nor the materials were significantly associated with the qualitative response variables or exerted any influence over the quantitative variables. More specifically, the use of the different materials was significantly associated with the frequency of gaps exclusively when loading was applied (Chi-square test, p = 0.029, CR > M > GIC). Though the marginal quality of cervical restorations may not be influenced by eccentric occlusal loading or the use of different materials, even in association in general, the unfavorable aspects of the use of the composite may be relevant, particularly in face of the existence of eccentric occlusal loads.