scholarly journals Non-Destructive Assessment of the Elastic Properties of Low-Grade CLT Panels

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1734
Author(s):  
Alexander Opazo-Vega ◽  
Franco Benedetti ◽  
Mario Nuñez-Decap ◽  
Nelson Maureira-Carsalade ◽  
Claudio Oyarzo-Vera
Keyword(s):  
Numerical Simulations ◽  
Elastic Properties ◽  
Transverse Vibration ◽  
Dynamic Properties ◽  
Local Variation ◽  
Radiata Pine ◽  
Structural Quality ◽  
Low Grade ◽  
High Concentrations ◽  
Local Variability

The use of cross-laminated timber panels (CLT) made of low-grade structural timber has steadily increased in developing countries. These panels usually present several natural defects, which can cause a high local variation of their orthotropic elastic properties, generating future structural serviceability problems. Our work aims to estimate the local variability of the elastic properties in low-grade CLT panels by combining nondestructive transverse vibration testing, numerical simulations, and regional sensitivity analysis (RSA). Four three-layer Radiata pine CLT panels were subjected to transverse vibration tests with supports at four points. Besides, a series of numerical simulations of the panels, considering the local variability of the elastic properties of the panels in eight zones, were carried out using the finite element method. Then, RSA analysis was performed to study in which ranges of values the panels’ elastic properties generated lower differences between the measured versus simulated dynamic properties. Finally, a structural quality control indicator was proposed for the CLT panels based on keeping low the probability that the elastic properties in the central zones do not exceed minimum acceptable values. The results obtained suggest that the proposed methodology is suitable for segregating CLT panels with high concentrations of defects such as pith presence.

scholarly journals Evaluation of Stiffness and Dynamic Properties of a Mine Shaft Steelwork Structure through In Situ Tests and Numerical Simulations

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 664
Author(s):  
Jacek Jakubowski ◽  
Przemysław Fiołek
Keyword(s):  
Numerical Simulations ◽  
Dynamic Properties ◽  
Vertical Motion ◽  
Load Test ◽  
Mode Shapes ◽  
Dynamic Amplification Factor ◽  
In Situ Tests ◽  
Mine Shaft ◽  
Numerical Investigations

A mine shaft steelwork is a three-dimensional frame that directs the vertical motion of conveyances in mine shafts. Here, we conduct field and numerical investigations on the stiffness and dynamic properties of these structures. Based on the design documentation of the shaft, materials data, and site inspection, the steelwork’s finite element model, featuring material and geometric non-linearities, was developed in Abaqus. Static load tests of steelwork were carried out in an underground mine shaft. Numerical simulations reflecting the load test conditions showed strong agreement with the in situ measurements. The validated numerical model was used to assess the dynamic characteristics of the structure. Dynamic linear and non-linear analyses delivered the natural frequencies, mode shapes, and structural response to dynamic loads. The current practices and regulations regarding shaft steelwork design and maintenance do not account for the stiffness of guide-to-bunton connections and disregard dynamic factors. Our experimental and numerical investigations show that these connections provide considerable stiffness, which leads to the redistribution and reduction in bending moments and increased stiffness of the construction. The results also show a high dynamic amplification factor. The omission of these features implicates an incorrect assessment of the design loads and can lead to over- or under-sized structures and ultimately to shortened design working life or failure.

Modal Simulation and Testing of a Micro-Manipulator

2004 ◽  
Vol 127 (3) ◽  
pp. 515-519 ◽  
Author(s):  
Yongjun Lai ◽  
Marek Kujath ◽  
Ted Hubbard
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Compliant Mechanism ◽  
Dynamic Properties ◽  
Experimental Results ◽  
Mass Model ◽  
Thermal Actuators ◽  
Micro Manipulator ◽  
Six Dof

A micro-machined manipulator with three kinematic degrees-of-freedom (DOF): x, y, and φ is presented. The manipulator is driven by three thermal actuators. A six DOF discrete spring-mass model of the compliant mechanism is developed which manifests the dynamic properties of the device. Numerical simulations are compared with experimental results.

scholarly journals First-Principles Design of Refractory High Entropy Alloy VMoNbTaW

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 965 ◽  
Author(s):  
Shumin Zheng ◽  
Shaoqing Wang
Keyword(s):  
Elastic Properties ◽  
First Principles ◽  
High Entropy Alloy ◽  
Low Density ◽  
High Entropy ◽  
System A ◽  
Small Influence ◽  
High Concentrations ◽  
General Guidance ◽  
Selection Of

The elastic properties of seventy different compositions were calculated to optimize the composition of a V–Mo–Nb–Ta–W system. A new model called maximum entropy approach (MaxEnt) was adopted. The influence of each element was discussed. Molybdenum (Mo) and tungsten (W) are key elements for the maintenance of elastic properties. The V–Mo–Nb–Ta–W system has relatively high values of C44, bulk modulus (B), shear modulus (G), and Young’s modulus (E), with high concentrations of Mo + W. Element W is brittle and has high density. Thus, low-density Mo can substitute part of W. Vanadium (V) has low density and plays an important role in decreasing the brittleness of the V–Mo–Nb–Ta–W system. Niobium (Nb) and tantalum (Ta) have relatively small influence on elastic properties. Furthermore, the calculated results can be used as a general guidance for the selection of a V–Mo–Nb–Ta–W system.

Progressive alveolar septal injury in primates exposed to 60% oxygen for 14 days

1994 ◽  
Vol 267 (6) ◽  
pp. L797-L806 ◽  
Author(s):  
J. D. Crapo ◽  
G. Hayatdavoudi ◽  
M. J. Knapp ◽  
P. J. Fracica ◽  
W. G. Wolfe ◽  
...  
Keyword(s):  
Clinical Medicine ◽  
Alveolar Type ◽  
Low Grade ◽  
Electron Microscopic ◽  
Morphometric Analyses ◽  
Tissue Changes ◽  
High Concentrations ◽  
Specific Tissue ◽  
Alveolar Septa ◽  
Lung Lobes

Moderate exposures to hyperoxia are becoming increasingly common in clinical medicine as advancing technology allows O2 to be more effectively delivered to nonintubated patients. The sensitivity of the lung to injury by a subchronic exposure to 60% O2 was investigated, using baboons and serial lobar biopsies. Because results obtained from different regions of the lung were compared, the alveolar architecture of different lung lobes of three controls was studied, with the use of electron microscopic morphometric analyses, to assess possible lobar differences in volume, surface, and numerical densities of cells and tissues. In animals exposed to 60% O2, the same techniques were used to assess specific tissue changes in the epithelial, interstitial, and endothelial compartments of the alveolar septa. All six lobes of the normal baboon lung were found to be identical with respect to alveolar architecture. Thus, for gases of low reactivity and given in high concentrations, such as O2, cross-comparisons between different lobes are appropriate. Exposure to 60% O2 was found to cause proliferation of alveolar type II epithelium, suggesting a low-grade, chronic epithelial injury. Animals allowed to recover for 8 wk in room air showed progressive changes in the alveolar interstitium, involving increases in both cells and matrix. Because sequential lobar resections were done, animals were exposed both to 60% O2 and to the effects of general anesthesia and thoracotomies. The exposure to 60% O2 for 2 wk in this experimental setting leads to an alveolar septal injury that includes a progressive interstitial fibrotic response.

003 Large-scale Numerical Simulations for Analyses of Visco-elastic Properties of Filled Rubber

2015 ◽  
Vol 2015.28 (0) ◽  
pp. _003-1_-_003-2_
Author(s):  
Hiroshi Kadowaki ◽  
Hare Tazawa ◽  
Hiroshi Shima ◽  
Gaku Hashimoto ◽  
Hiroshi Okuda ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Elastic Properties ◽  
Large Scale ◽  
Filled Rubber

Effects of Vitamin D Status on Inflammatory Markers in Obese Subjects: A Systematic Review

2020 ◽  
Vol 16 (3) ◽  
pp. 268-275
Author(s):  
Geórgia R.R. de Alencar ◽  
Lailton da Silva Freire ◽  
Beatriz de Mello Pereira ◽  
Verbena R. da Silva ◽  
Aline C. Holanda ◽  
...  
Keyword(s):  
Systematic Review ◽  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Inflammatory Markers ◽  
Observational Studies ◽  
The Body ◽  
Low Grade ◽  
Vitamin D Status ◽  
Obese Subjects ◽  
High Concentrations

Background: Recent studies have demonstrated the role of micronutrients in the manifestation of comorbidities associated with obesity. Vitamin D deficiency, in particular, appears to be associated with increased levels of inflammatory markers, which may lead to chronic low-grade inflammation, elevating the risk of chronic diseases such as diabetes, metabolic syndrome, and cardiovascular disease. The objective of this study was to perform a systematic review of observational studies conducted to investigate the effect of vitamin D deficiency on inflammatory markers in obese subjects. Methodology: This systematic review was conducted in accordance with the “STROBE” and PRISMA recommendations. Observational studies that evaluated the effect of vitamin D status on inflammatory markers in obese subjects were selected and reviewed. Searches were conducted in the PubMed, SciVerse Scopus, and Web of Science databases from February 21 to 22, 2018. Results: After the selection and removal of duplicate articles, 10 eligible articles were identified. Results from eight observational studies showed an association between vitamin D deficiency or insufficiency in the body and increased concentrations of inflammatory markers in obese individuals. On the other hand, two of the studies did not demonstrate any correlation. With regard to the inflammatory markers evaluated, eight studies showed high concentrations of ultra-sensitive C-reactive protein, five studies found an increase in interleukin-6 concentrations, and two studies noted increased levels of tumor necrosis factor. Conclusion: The data presented in this systematic review provide evidence of the association between vitamin D deficiency and increased inflammation in obesity.

OS0302-212 A Study on Visco-elastic Properties of Filled-rubber with Large-scale Numerical Simulations

2015 ◽  
Vol 2015 (0) ◽  
pp. _OS0302-21-_OS0302-21
Author(s):  
Hiroshi KADOWAKI ◽  
Hare TAZAWA ◽  
Hiroshi SHIMA ◽  
Gaku HASHIMOTO ◽  
Hiroshi OKUDA ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Elastic Properties ◽  
Large Scale ◽  
Filled Rubber

Equilibrium and Dynamic Properties of Dislocation Dipoles

2006 ◽  
Vol 976 ◽  
Author(s):  
Patrick Veyssiere
Keyword(s):  
Elastic Properties ◽  
Dynamic Properties ◽  
Nucleation And Growth ◽  
Orientation Dependence ◽  
Self Organization ◽  
Dynamical Process ◽  
Dipolar Interactions ◽  
Single Slip ◽  
Anisotropic Elastic ◽  
Constrained Deformation

AbstractThis paper embraces several aspects related to dislocation self-organization in single slip. The formation of prismatic loops, seminal to the nucleation and growth of dislocation braids, is a dynamical process involving elastic dipolar interactions. Preliminary simulations of the concerted process of loop generation are presented. Elastic properties of dislocation dipoles are analysed as a function of dipole character. Equilibrium properties are investigated under the isotropic and anisotropic elastic approximations. The orientation dependence of the so-called dipole passing stress is examined, and its implication in the elementary mechanisms that take place under constrained deformation conditions, such as fatigue cycling, are discussed.

scholarly journals First-principles calculations of structural, electronic, magnetic and elastic properties of Mo 2 FeB 2 under high pressure

2018 ◽  
Vol 5 (7) ◽  
pp. 172247
Author(s):  
Bin Wang ◽  
Benyuan Ma ◽  
Wei Song ◽  
Zhe Fu ◽  
Zhansheng Lu
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Elastic Properties ◽  
First Principles ◽  
Dynamic Properties ◽  
Magnetic Moments ◽  
Debye Model ◽  
Ferromagnetic Phase ◽  
First Principles Calculations ◽  
Anisotropy Index

The structural, electronic, magnetic and elastic properties of Mo 2 FeB 2 under high pressure have been investigated with first-principles calculations. Furthermore, the thermal dynamic properties of Mo 2 FeB 2 were also studied with the quasi-harmonic Debye model. The volume of Mo 2 FeB 2 decreases with the increase in pressure. Using the analysis of the density of the states, atom population and Mulliken overlap population, it is observed that as the pressure increases, the B–B bonds are strengthened and the B–Mo covalency decreases. Moreover, for all pressures, Mo 2 FeB 2 is detected in the anti-ferromagnetic phase and the magnetic moments decrease with the increase in pressure. The calculated bulk modulus, shear modulus, Young's modulus, Poisson's ratio and universal anisotropy index all increase with the increase in pressure. From thermal expansion coefficient analysis, it is found that Mo 2 FeB 2 shows good volume invariance under high pressure and temperature. The examination of the dependence of heat capacity on the temperature and pressure shows that heat capacity is more sensitive to temperature than to pressure.

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