scholarly journals Analysis of the Viscoelastic Sphere Impact against a Viscoelastic Uflyand-Mindlin Plate considering the Extension of Its Middle Surface

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Yury A. Rossikhin ◽  
Marina V. Shitikova ◽  
Phan Thanh Trung
Keyword(s):  
Contact Force ◽  
Middle Surface ◽  
Hertzian Contact ◽  
Mindlin Plate ◽  
Strong Discontinuity ◽  
Time Duration ◽  
Suggested Approach ◽  
Viscoelastic Sphere ◽  
The Impact ◽  
Contact Domain

In the present paper, the problem on impact of a viscoelastic sphere against a viscoelastic plate is considered with due account for the extension of plate’s middle surface and local bearing of sphere and plate’s materials via the Hertz theory. The standard linear solid models with conventional derivatives and with fractional-order derivatives are used as viscoelastic models, respectively, outside and within the contact domain. As a result of impact, transient waves (surfaces of strong discontinuity) are generated in the plate, behind the wave fronts of which up to the boundaries of the contact domain the solution is constructed in terms of one-term ray expansions due to short-time duration of the impact process. The motion of the contact zone occurs under the action of extension forces acting in the plate’s middle surface, transverse force, and the Hertzian contact force. The suggested approach allows one to find the time-dependence of the impactor’s indentation into the target and the Hertzian contact force.

The Impact of a Sphere on a Timoshenko Thin-Walled Beam of Open Section With due Account for Middle Surface Extension

1999 ◽  
Vol 121 (4) ◽  
pp. 375-383 ◽  
Author(s):  
Yu. A. Rossikhin ◽  
M. V. Shitikova
Keyword(s):  
Contact Force ◽  
Contact Region ◽  
Middle Surface ◽  
Arbitrary Cross Section ◽  
Rate Of Change ◽  
Abel Equation ◽  
Strong Discontinuity ◽  
Open Section ◽  
Thin Walled ◽  
The Impact

The problem on the normal impact of an elastic sphere upon an elastic Timoshenko arbitrary cross section thin-walled beam of open section is considered. The process of impact is accompanied by the dynamic flexure and torsion of the beam, resulting in the propagation of plane flexural-warping and torsional-shear waves of strong discontinuity along the beam axis. In addition, the process of impact is accompanied by large transverse deformations and large deflection of the beam in the place of impact, with the consequent generation of longitudinal shock waves and large membrane contractive (tensile) forces. Behind the wave fronts up to the boundaries of the contact region (the beam part with the contact spot), the solution is constructed in terms of one-term ray expansions. During the impact, the sphere moves under the action of the contact force which is determined due to the Hertz’s theory, but the contact region moves under the attraction of the contact force, as well as the twisting and bending-torsional moments and transverse and membrane forces, which are applied to the lateral surfaces of the contact region. Simultaneous consideration of the equations of sphere and the contact region motion leads to the Abel equation of the second kind, wherein the value characterizing the sphere and beam drawing together and the rate of change of this value are used as the independent variable and the function, respectively. The solution to the Abel equation written in the form of a series allows one to determine all characteristics of the shock interaction of the sphere and beam.

Identification of Impact Damping of Two Elastic Bodies

1999 ◽  
Author(s):  
Haiyan Hu ◽  
Dongping Jin
Keyword(s):  
Contact Force ◽  
Time History ◽  
Hertzian Contact ◽  
New Technique ◽  
Restoring Force ◽  
Nonlinear Spring ◽  
Elastic Bodies ◽  
Measured Time ◽  
The Impact ◽  
Impact Damping

Abstract The contact force of two impacting elastic bodies is widely modeled as the parallel combination of a nonlinear spring and a nonlinear dashpot. The restoring force of the nonlinear spring can be determined according to the Hertzian contact law in elasticity, while the model and corresponding parameters of the nonlinear damping force have to be identified through experiments. The current approaches of damping identification are based on the measured time histories of both contact force and relative approaching velocity of two impacting bodies. In this paper, a new technique is presented for the damping identification on the basis of measured time history of the contact force only. Hence, the tough problem of measuring the relative approaching velocity of two impacting bodies just before impact is removed. The efficacy test of the new technique is given in the paper through an example of identifying the impact damping of a pair of clamped beams.

scholarly journals Reciprocal hemizygosity analysis reveals that the Saccharomyces cerevisiae CGI121 gene affects lag time duration in synthetic grape must

2021 ◽  
Author(s):  
Runze Li ◽  
Rebecca C Deed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperatures ◽  
Lag Time ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Time Duration ◽  
Phase Duration ◽  
Grape Must ◽  
The Impact ◽  
Reciprocal Hemizygosity Analysis

Abstract It is standard practice to ferment white wines at low temperatures (10-18 °C). However, low temperatures increase fermentation duration and risk of problem ferments, leading to significant costs. The lag duration at fermentation initiation is heavily impacted by temperature; therefore, identification of Saccharomyces cerevisiae genes influencing fermentation kinetics is of interest for winemaking. We selected 28 S. cerevisiae BY4743 single deletants, from a prior list of open reading frames (ORFs) mapped to quantitative trait loci (QTLs) on chromosomes VII and XIII, influencing the duration of fermentative lag time. Five BY4743 deletants, Δapt1, Δcgi121, Δclb6, Δrps17a, and Δvma21, differed significantly in their fermentative lag duration compared to BY4743 in synthetic grape must (SGM) at 15 °C, over 72 h. Fermentation at 12.5 °C for 528 h confirmed the longer lag times of BY4743 Δcgi121, Δrps17a, and Δvma21. These three candidate ORFs were deleted in S. cerevisiae RM11-1a and S288C to perform single reciprocal hemizygosity analysis (RHA). RHA hybrids and single deletants of RM11-1a and S288C were fermented at 12.5 °C in SGM and lag time measurements confirmed that the S288C allele of CGI121 on chromosome XIII, encoding a component of the EKC/KEOPS complex, increased fermentative lag phase duration. Nucleotide sequences of RM11-1a and S288C CGI121 alleles differed by only one synonymous nucleotide, suggesting that intron splicing, codon bias, or positional effects might be responsible for the impact on lag phase duration. This research demonstrates a new role of CGI121 and highlights the applicability of QTL analysis for investigating complex phenotypic traits in yeast.

scholarly journals Modeling and Optimization Sustainable Forest Supply Chain Considering Discount in Transportation System and Supplier Selection under Uncertainty

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 964
Author(s):  
Komeyl Baghizadeh ◽  
Dominik Zimon ◽  
Luay Jum’a
Keyword(s):  
Supply Chain ◽  
Working Hours ◽  
Mixed Integer ◽  
Forest Industry ◽  
Northern Iran ◽  
Suggested Approach ◽  
Tactical Decisions ◽  
Environmental Goals ◽  
Forest Supply Chain ◽  
The Impact

In recent decades, the forest industry has been growingly expanded due to economic conditions, climate changes, environmental and energy policies, and intense demand changes. Thus, appropriate planning is required to improve this industry. To achieve economic, social and environmental goals, a supply chain network is designed based on a multi-period and multi-product Mixed-Integer Non-Linear Programming (MINLP) model in which the objective is to maximize the profit, minimize detrimental environmental effects, improve social effects, and minimize the number of lost demands. In addition, to improve forest industry planning, strategic and tactical decisions have been implemented throughout the supply chain for all facilities, suppliers and machinery. These decisions significantly help to improve processes and product flows and to meet customers’ needs. In addition, because of the presence of uncertainty in some parameters, the proposed model was formulated and optimized under uncertainty using the hybrid robust possibilistic programming (HRPP-II) approach. The -constraint technique was used to solve the multi-objective model, and the Lagrangian relaxation (LR) method was utilized to solve the model of more complex dimensions. A case study in Northern Iran was conducted to assess the efficiency of the suggested approach. Finally, a sensitivity analysis was performed to determine the impact of important parameters on objective functions. The results of this study show that increasing the working hours of machines instead of increasing their number, increasing the capacity of some facilities instead of establishing new facilities and expanding the transport fleet has a significant impact on achieving predetermined goals.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

Hertz Contact Force Model With Permanent Indentation in Impact Analysis of Solids

1992 ◽  
Author(s):  
Hamid M. Lankarani ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Impact Analysis ◽  
Equations Of Motion ◽  
Solid Particles ◽  
Hertzian Contact ◽  
Contact Period ◽  
Force Model ◽  
Unknown Parameters ◽  
Contact Force Model ◽  
Energy And Momentum

Abstract A continuous analysis method for the direct-central impact of two solid particles is presented. Based on the assumption that local plasticity effects are the sole factor accounting for the dissipation of energy in impact, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are analytically evaluated in terms of a given coefficient of restitution and velocities before impact. The equations of motion of the two solids may then be integrated forward in time knowing the variation of the contact force during the contact period. For Illustration, an impact of two soft metallic particles is studied.

The Impact of Video Speed on the Estimation of Time Duration in Sport

2021 ◽  
pp. 1-11
Author(s):  
Lisa-Marie Schütz ◽  
Geoffrey Schweizer ◽  
Henning Plessner
Keyword(s):  
Real Time ◽  
Time Estimation ◽  
Slow Motion ◽  
Sport Performance ◽  
Time Duration ◽  
Video Presentation ◽  
Sporting Activities ◽  
The Impact ◽  
Estimation Of Time

The authors investigated the impact of video speed on judging the duration of sport performance. In three experiments, they investigated whether the speed of video presentation (slow motion vs. real time) has an influence on the accuracy of time estimation of sporting activities (n1 = 103; n2 = 100; n3 = 106). In all three studies, the time estimation was more accurate in real time than in slow motion, in which time was overestimated. In two studies, the authors initially investigated whether actions in slow motion are perceived to last longer because the distance they cycled or ran is perceived to be longer (n4 = 92; n5 = 106). The results support the hypothesis that the duration of sporting activities is estimated more accurately when they are presented in real time than in slow motion. Sporting officials’ judgments that require accurate time estimation may thus be biased when based on slow-motion displays.

Analysis of Externalities of Economic Activity of the Enterprise

2021 ◽  
Vol 2021 (2) ◽  
pp. 86-94
Author(s):  
Dmytro V. Kozlov
Keyword(s):  
Transaction Costs ◽  
Economic Activity ◽  
Environmental Externalities ◽  
Negative Externalities ◽  
Time Duration ◽  
Marginal Costs ◽  
Positive Externalities ◽  
State And Market ◽  
The Impact

The problems of research of internalities and externalities with the further development of the general classification of externalities of economic activity of the enterprise are defined. The influence of negative and positive externalities on society and enterprise is considered. The concept of negative externalities differs from transaction costs. It is noted that transaction costs can be reflected in cash and can be offset by market inclusion in the price of the products, but this is not possible for externalities. It is emphasized that the purpose of economic activity of any enterprise is to exceed the positive externalities over the negative and achieve the maximum difference between them. The different time duration of the impact of the enterprise on third parties is given. The sign of externalities on the scale of action is emphasized. The externalities of the enterprise are considered in their essence according to the principles of sustainable development, highlighting economic, social and environmental externalities. It is emphasized that economic externalities can arise in the course of the whole business cycle of full-fledged work of all parts of the enterprise. In contrast to economic, social externalities affect people both within the enterprise, that is workers and citizens of the society in which the enterprise operates. And when it comes to environmental externalities, the mediator between the source and recipient of externalities is the environment. Externalities are distinguished according to the means of accounting and the degree of influence on the subject of perception. The necessity of regulation of externalities through internalization and actions of the enterprise with the help of state and market instruments is substantiated. It is emphasized that internalization is the transformation of negative externalities into positive ones in terms of convergence of marginal costs and benefits of the enterprise to marginal social costs and utility.

Size and Temperature Dependent Deposition Model of Micro-Sized Sand Particles

2017 ◽  
Author(s):  
Kuahai Yu ◽  
Danesh Tafti
Keyword(s):  
Contact Force ◽  
Adhesion Force ◽  
Stokes Number ◽  
Experimental Result ◽  
Contact Radius ◽  
Recovery Stage ◽  
Line Force ◽  
Plastic Stage ◽  
Sand Particles ◽  
The Impact

Sand ingestion and deposition in gas turbine engine components can lead to several operational hazards. This paper discusses a physics based model for modeling the impact and deposition of sand particles. The collision model divides the impact process into three stages, the elastic stage, the elastic-plastic stage, and full plastic stage. The recovery stage is assumed to be fully elastic. The contact force, contact radius and work of contact force are conformed to the Hertzian theory, using “Young’s modulus similarity” rule to predict the recovery displacement. The adhesion loss in the recovery stage is considered using Dunn’s model, which describes the adhesion force as an idealized line force with the contact radius. The validation case of steel spherical particle impact on a glass surface with the maximum Stokes number of 10000, shows that the adhesion model with elastoplastic impact model describes the experimental result well. When the Stokes number is less than 12, the particle deposits on the surface. Sand properties are characterized by size and temperature dependencies. Model predictions for particle sizes ranging from 0.5 to 50 micron, impact velocities up to 80 m/s, and temperatures above 1300 K are given and discussed. It is shown that both size and temperature have an effect on the deposition characteristics.

Analytical Study of the Oblique Impact of a Rod with a Flat Using an Elasto-Plastic Contact Model

2015 ◽  
Vol 801 ◽  
pp. 25-32
Author(s):  
Ozdes Cermik ◽  
Hamid Ghaednia ◽  
Dan B. Marghitu
Keyword(s):  
Impact Velocity ◽  
Contact Force ◽  
Analytical Study ◽  
Initial Conditions ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Contact Model ◽  
Impact Angles ◽  
The Impact

In the current study a flattening contact model, combined with a permanent deformation expression, has been analyzed for the oblique impact case. The model has been simulated for different initial conditions using MATLAB. The initial impact velocity used for the simulations ranges from 0.5 to 3 m/s. The results are compared theoretically for four different impact angles including 20, 45, 70, and 90 degrees. The contact force, the linear and the angular motion, the permanent deformation, and the coefficient of restitution have been analyzed. It is assumed that sliding occurs throughout the impact.

Sign in / Sign up

Export Citation Format

Share Document