Search results for "Elastic modulus"
showing 10 items of 189 documents
Rippling of two-dimensional materials by line defects
2020
Two-dimensional materials and their mechanical properties are known to be profoundly affected by rippling deformations. However, although ripples are fairly well understood, less is known about their origin and controlled modification. Here, motivated by recent reports of laser-controlled creation of line defects in graphene, we investigate how line defects could be used to control rippling in graphene and other two-dimensional materials. By sequential multi-scale coupling of density-functional tight-binding and continuum elasticity simulations, we quantify the amount of rippling when the number and the cumulative length of the line defects increase. Simulations show that elastic sheets wit…
A study on stress distribution to cement layer and root dentin for post and cores made of CAD/CAM materials with different elasticity modulus in the …
2019
Background To evaluate the stress distribution in a maxillary central incisor with different post and cores made of six CAD/CAM materials with different elastic modulus in the absence of ferrule using the finite element analysis. Material and methods A three-dimensional endodontically treated maxillary central incisor restored with an all-ceramic crown was modelled in Rhinoceros (5.0 SR8, McNeel). The geometries were analyzed in ANSYS 17.2 (ANSYS Inc.) considering isotropic, homogeneous, linearly elastic materials with perfectly bonded contacts. The elastic moduli (E) of the post-and-cores defined the groups to be compared: nanoceramic resin (E=12.8GPa); composite resin (E=16GPa); hybrid ce…
Influence of different restorative materials on the stress distribution in dental implants
2018
Background To assist clinicians in deciding the most suitable restorative materials to be used in the crowns and abutment in implant rehabilitation. Material and methods For finite element analysis (FEA), a regular morse taper implant was created using a computer aided design software. The implant was inserted at the bone model with 3 mm of exposed threads. An anatomic prosthesis representing a first maxillary molar was modeled and cemented on the solid abutment. Considering the crown material (zirconia, chromium-cobalt, lithium disilicate and hybrid ceramic) and abutment (Titanium and zirconia), the geometries were multiplied, totaling eight groups. In order to perform the static analysis,…
Atlas for the properties of elemental two-dimensional metals
2018
Common two-dimensional (2D) materials have a layered three-dimensional (3D) structure with covalently bonded, atomically thin layers held together by weak van der Waals forces. However, in a recent transmission electron microscopy experiment, atomically thin 2D patches of iron were discovered inside a graphene nanopore. Motivated by this discovery, we perform a systematic density-functional study on atomically thin elemental 2D metal films, using 45 metals in three lattice structures. Cohesive energies, equilibrium distances, and bulk moduli in 2D are found to be linearly correlated to the corresponding 3D bulk properties, enabling the quick estimation of these values for a given 2D metal a…
Aluminum oxide from trimethylaluminum and water by atomic layer deposition:The temperature dependence of residual stress, elastic modulus, hardness a…
2014
Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by na…
Evaluation of Subgrade Resilient Modulus Predictive Model for Use in Mechanistic-Empirical Pavement Design Guide
2006
The characterization of unbound materials in the mechanistic–empirical pavement design guide (MEPDG), also known as the 2002 design guide, is reviewed, and this characterization is applied to Minnesota subgrades. The main emphasis is on the collection of k1-, k2-, and k3-parameters for Minnesota fine-grained soils and the procedure for the interpretation of the resilient modulus test to provide an input to the multilayer elastic theory (MLET) analysis (Level 2 input). This is an important aspect of adaptation of the MEPDG, because the guide recommends measurement of resilient moduli from laboratory testing, but the procedure does not specify how to interpret the test data to obtain an input …
Influence of the volume of restorative material on the concentration of stresses in the restorative interface.
2020
Background To evaluate the microtensile strength in the adhesive interface depending on the volume of the composite resin used to restore class I cavities. Material and Methods Forty-eight human third molars received a standardized class I cavity preparation and they were separated into six experimental groups: G1 - single-bottle adhesive system; G2 - bonding system with load; G3 - single-bottle adhesive associated with low-viscosity composite resin; G4 - loaded adhesive associated with low-viscosity composite; G5 - resin-modified glass ionomer associated with single-bottle adhesive; and G6 - resin-modified glass ionomer associated with loaded adhesive. All cavities were restored with a uni…
Interaction of Nanometric Clay Platelets
2008
International audience; The free energy of interaction between two nanometric clay platelets immersed in an electrolyte solution has been calculated using Monte Carlo simulations as well as direct integration of the configurational integral. Each platelet has been modeled as a collection of charged spheres carrying a unit chargethe face of a platelet contains negative charges, and the edge, positive charges. The calculations predict that a configuration of “overlapping coins” is the global free energy minimum at intermediate salt concentrations (10−100 mM). A second weaker minimum, corresponding to the well-known “house of cards” configuration, also appears in this salt interval. At low sal…
Effect of Elongational Flow and Polarity of Organomodified Clay on Morphology and Mechanical Properties of a PLA Based Nanobiocomposite
2016
Abstract In biodegradable polymer world nanobiocomposites represent a new group of materials filled with inert nanoparticles that shows very interesting properties and the biodegradability of the matrix. In this work we have studied the effect of the polarity of the organomodified montmorillonite and of the elongational flow on the morphology and the rheological and mechanical properties of a new nanobiocomposite with a matrix of biodegradable PLA based blend. The elastic modulus enhances in presence of the nanofiller and this increase is larger and larger with the increment of the orientation. The tensile strength does not show any significant change at the same level of orientation. Moreo…
Correlations between transmural mechanical and morphological properties in porcine thoracic descending aorta.
2015
Determination of correlations between transmural mechanical and morphological properties of aorta would provide a quantitative baseline for assessment of preventive and therapeutic strategies for aortic injuries and diseases. A multimodal and multidisciplinary approach was adopted to characterize the transmural morphological properties of descending porcine aorta. Histology and multi-photon microscopy were used for describing the media layer micro-architecture in the circumferential-radial plane, and Fourier Transform infrared imaging spectroscopy was utilized for determining structural protein, and total protein content. The distributions of these quantified properties across the media thi…