Search results for "force"
showing 10 items of 3423 documents
One-dimensional heterogeneous solids with uncertain elastic modulus in presence of long-range interactions: Interval versus stochastic analysis
2013
The analysis of one-dimensional non-local elastic solids with uncertain Young's modulus is addressed. Non-local effects are represented as long-range central body forces between non-adjacent volume elements. For comparison purpose, the fluctuating elastic modulus of the material is modeled following both a probabilistic and a non-probabilistic approach. To this aim, a novel definition of the interval field concept, able to limit the overestimation affecting ordinary interval analysis, is introduced. Approximate closed-form expressions are derived for the bounds of the interval displacement field as well as for the mean-value and variance of the stochastic response.
A Method to Evaluate Chewing Efficiency in Infants Through Food Bolus Characterization: A Preliminary Study
2015
Chewing skills develop greatly during the two first years of life, but the evolution of masticatory efficiency has never been directly measured so far. A bottleneck for such study is the difficulty in using the chew-and-spit method with infants and very young children. Herein, we propose a new method based on a model gel enclosed in a food feeder, which has been assessed with adult subjects. Subjects chewed and compressed the gel either alone or enclosed in two different feeders. Analysis of the number of particles and particle area distribution revealed that one feeder,made from silicone teat, interfered with bolus breakdown. However, similar results were observed between experiments in a …
Dielectric polarization and polarizability of 1-pentanol+n-octane mixtures from static dielectric constant and refractive index data at 0,25 and 45�C
1990
Static dielectric constants and refractive indices of 1-pentanol+n-octane mixtures were measured in the temperature range between 0 and 45°C. Data discussed in terms of Kirkwood correlation factor and Lorentz-Lorenz molar refractivity give information on the short range intermolecular interactions between the components. The role played by the nonpolar n-octane in the destruction of 1-pentanol oligomers is also pointed out.
Structural symmetry breaking in octupolar tetrastyrylpyrazines and their dipole moments in equilibrium ground and Franck-Condon excited state
2018
Abstract From electrooptical absorption measurements (EOAM) follows that the dipole moment of octupolar tetrastyrylpyrazines in the equilibrium ground state is large and that the change of dipole moments upon transition to the excited Franck–Condon state is significant. Obtained results unambiguously testify to structural symmetry breaking in the studied octupolar tetrastyrylpyrazines. Molecular mechanics and semi-empirical calculations evidence that tetrastyrylpyrazines have non-planar configurations. The non-planar geometry of the molecules causes large μg values and significant change of dipole moment Δaμ after excitation. Due to large μg and Δaμ values the maxima of the first absorption…
Dipole Moment Surface of the van der Waals Complex CH4–N2
2010
The interaction-induced dipole moment surface of the van der Waals CH(4)-N(2) complex has been calculated for a broad range of intermolecular separations R and configurations in the approximation of the rigid interacting molecules at the MP2 and CCSD(T) levels of theory using the correlation-consistent aug-cc-pVTZ basis set with the basis set superposition error correction. The simple model to account for the exchange effects in the range of small overlap of the electron shells of interacting molecules and the induction and dispersion interactions for large R has been suggested. This model allows describing the dipole moment of van der Waals complexes in analytical form both for large R, wh…
Considerations on the dipole moment of molecules forming the twisted intramolecular charge transfer state
1992
Several derivatives of dual-fluorescing dimethylaminobenzonitrile (DMABN) are compared regarding their ground and excited-state dipole moments extracted from electro-optical emission and solvatochromic measurements. The comparison includes bridged model compounds as well as compounds with different degrees of steric hindrance to planarity, as well as ester and carbazolyl derivatives. The results are discussed on the basis of the twisted intramolecular charge transfer (TICT) model, the most widely accepted model. They show that (i) the dipole moment of the A (TICT) state (long-wavelength band) shows only little solvent sensitivity (polarizability), (ii) this observed small dependence of the …
Convolution-based ensemble learning algorithms to estimate the bond strength of the corroded reinforced concrete
2022
Reinforced concrete bond strength deterioration is one of the most serious problems in the construction industry. It is one of the most common factors impacting structural deterioration and the major cause of premature decadence of reinforced concrete structures. Therefore, developing an accurate model with the lowest variance and high reliability for the bond strength of corroded reinforced concrete is very important. The current work evaluates the efficiency of convolution-based ensemble learning algorithms. To address these issues, convolution-based ensemble learning models are developed using a database collected from the previous experimental studies of relative bond strength for corro…
Steel-concrete bond in lightweight fiber reinforced concrete under monotonic and cyclic actions
2005
Experimental results of the local bond stress-slip relationship of reinforcing bars embedded in lightweight fiber reinforced concrete with expanded clay aggregates are presented. The effect of the following parameters were investigated: - dimension of specimens; - anchorage length; - percentages of hooked steel fibers; - geometrical ratio of transverse reinforcement; - confinement external transverse pressure. Prismatic specimens with deformed steel bars embedded for a fixed length equal to five and eight equivalent diameters were tested under both monotonic and cyclic reversal imposed displacements at the tip of the bars, in controlled displacement tests. The influence of the above mention…
A HYBRID VEM/BEM NUMERICAL TECHNIQUE FOR SIMULATING DAMAGE IN COMPOSITE MATERIALS
2021
Composite materials are nowadays widely used in the aerospace sector both for primary and secondary structures for their high mechanical properties and the ability to model them according to project needs. Therefore, accurately predicting material behaviour when subjected to operating loads is extremely important in making the design process more efficient. For this purpose, computational approaches based on continuum damage mechanics have been largely used to study the progressive loss of material integrity due to the propagation and coalescence of microscopic defects. In this contribution, a recently developed hybrid computational technique, which combines the Virtual Element Method (VEM)…
Coupling BEM and VEM for the Analysis of Composite Materials with Damage
2021
Numerical tools which are able to predict and explain the initiation and propagation of damage at the microscopic level in heterogeneous materials are of high interest for the analysis and design of modern materials. In this contribution, we report the application of a recently developed numerical scheme based on the coupling between the Virtual Element Method (VEM) and the Boundary Element Method (BEM) within the framework of continuum damage mechanics (CDM) to analyze the progressive loss of material integrity in heterogeneous materials with complex microstructures. VEM is a novel numerical technique that, allowing the use of general polygonal mesh elements, assures conspicuous simplific…