On Viscoelastic Compliant Contact-Impact Models

2004 ◽  
Vol 71 (1) ◽  
pp. 134-138 ◽  
Author(s):  
T. M. Atanackovic ◽  
D. T. Spasic
Keyword(s):  
Deformable Body ◽  
Viscoelastic Body ◽  
Rigid Wall ◽  
Straight Line ◽  
The Laplace Transform ◽  
Contact Impact ◽  
The Impact ◽  
Derivatives Of ◽  
Impact Models ◽  
Straight Rod

We study dynamics of a mass, moving on a straight line, and impacting against the rigid wall through a deformable body, that we model as a straight rod of negligible mass. The chosen constitutive model of the viscoelastic body comprises fractional derivatives of stress and strain and the restrictions on the coefficients that follow from Clausius Duhem inequality. We show that the dynamics of the problem is governed by a single differential equation of real order. The obtained equation was solved numerically. The comparison is made to the solution obtained by the Laplace transform and Post’s inversion formula. The predictions of the model concerning the duration of the impact, maximal values of the impacting force and deformation as well as the restitution coefficient are determined for several values of system parameters.

ON IMPACT SCRIPTS WITH BOTH FRACTIONAL AND DRY FRICTION TYPE OF DISSIPATION

2012 ◽  
Vol 22 (04) ◽  
pp. 1250076 ◽  
Author(s):  
NENAD GRAHOVAC ◽  
MIODRAG ZIGIC ◽  
DRAGAN SPASIC
Keyword(s):  
Dry Friction ◽  
Viscoelastic Body ◽  
Inequality Constraint ◽  
Rigid Wall ◽  
Friction Model ◽  
Slack Variable ◽  
Coulomb Friction Model ◽  
The Impact ◽  
Derivatives Of ◽  
Straight Rod

We study the dynamics of a mass, sliding on a dry surface and impacting against a rigid wall through a viscoelastic body, that we model as a straight rod of negligible mass. The problem comprises a constitutive model of the viscoelastic body with fractional derivatives of stress and strain, restrictions on the coefficients that follow from Clausius–Duhem inequality, and discontinuous inequality constraint conditions imposed by the Coulomb friction model. We show that the dynamics of the problem is governed by a single integro-differential inclusion. By use of the slack variable algorithm the problem was solved numerically. The predictions of the model concerning the duration of the impact, maximal values of the impacting force and deformation, as well as the restitution coefficient are determined for several values of system parameters. Depending on the dry friction coefficient three different impact scripts are identified: rebound after the impact, capture in the approaching phase, and capture in the rebound phase.

scholarly journals Statistical Weather-Impact Models: An Application of Neural Networks and Mixed Effects for Corn Production over the United States

2016 ◽  
Vol 55 (11) ◽  
pp. 2509-2527 ◽  
Author(s):  
Jordane A. Mathieu ◽  
Filipe Aires
Keyword(s):  
United States ◽  
The United States ◽  
Weather Data ◽  
Corn Yield ◽  
Mixed Effect ◽  
Local Conditions ◽  
Weather Impact ◽  
Yield Forecasting ◽  
The Impact ◽  
Impact Models

AbstractStatistical meteorological impact models are intended to represent the impact of weather on socioeconomic activities, using a statistical approach. The calibration of such models is difficult because relationships are complex and historical records are limited. Often, such models succeed in reproducing past data but perform poorly on unseen new data (a problem known as overfitting). This difficulty emphasizes the need for regularization techniques and reliable assessment of the model quality. This study illustrates, in a general way, how to extract pertinent information from weather data and exploit it in impact models that are designed to help decision-making. For a given socioeconomic activity, this type of impact model can be used to 1) study its sensitivity to weather anomalies (e.g., corn sensitivity to water stress), 2) perform seasonal forecasting (yield forecasting) for it, and 3) quantify the longer-term (several decades) impact of weather on it. The size of the training database can be increased by pooling data from various locations, but this requires statistical models that are able to use the localization information—for example, mixed-effect (ME) models. Linear, neural-network, and ME models are compared, using a real-world application: corn-yield forecasting over the United States. Many challenges faced in this paper may be encountered in many weather-impact analyses: these results show that much care is required when using space–time data because they are often highly spatially correlated. In addition, the forecast quality is strongly influenced by the training spatial scale. For the application that is described herein, learning at the state scale is a good trade-off: it is specific to local conditions while keeping enough data for the calibration.

Numerical Simulation on Concrete Median Barrier for Reducing Concrete Fragment Under Harsh Impact Loading of a 25-ton Truck

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Jaeha Lee ◽  
Goangseup Zi ◽  
Ilkeun Lee ◽  
Yoseok Jeong ◽  
Kyeongjin Kim ◽  
...  
Keyword(s):  
Impact Loading ◽  
Traffic Accident ◽  
Impact Analysis ◽  
Threshold Value ◽  
Rigid Wall ◽  
Wire Mesh ◽  
Element Size ◽  
Preliminary Study ◽  
The Impact ◽  
Controlling Behaviors

Recently, there was a collision accident involving vehicle–concrete median barrier in South Korea, and unfortunately, passengers on the opposite direction road were killed by the flying broken pieces of concrete generated by the collision. Primarily after this accident, we felt the need for developing an improved concrete median barrier up to level of SB6 impact severity in order to minimize the amount of broken pieces of concrete and any possibility of traffic accident casualty under the impact loading of truck. Accordingly, in this study, several designs of concrete median barriers have been examined, and a preliminary study has been conducted for developing and verifying appropriate collision model. First, type of vehicle was selected based on impact analysis on rigid wall. Then, the effects of element size and other key parameters on the capacity of the concrete median barrier under impact were studied. It was found that the key parameters for controlling behaviors of the median barrier under impact loading were contact option, threshold value, and mesh and boundary conditions. Furthermore, as a parametric study, effect of geometry and amount of wire-mesh or steel rebar in concrete median barrier on impact resistances of median barrier for reducing the collision debris were investigated. The amount of volume loss after the collision of truck was compared for various reinforcement ratios.

NUKLEUS - User-relevant and applicable kilometer-scale climate information for Germany

2021 ◽  
Author(s):  
Kevin Sieck ◽  
Bente Tiedje ◽  
Hendrik Feldmann ◽  
Joaquim Pinto
Keyword(s):  
Climate Models ◽  
Local Scale ◽  
Easy Access ◽  
Climate Information ◽  
Post Processing ◽  
Last Mile ◽  
Wide Range ◽  
Impact Modelling ◽  
The Impact ◽  
Impact Models

<p>Given the current developments in climate science it becomes more a more feasible to provide climate information at the kilometer-scale from convection-permitting climate simulations. This progress will enable many users to directly feed high-resolution climate information into their impact-models for climate impact studies at the local scale. Examples include urban heat stress at street level or the design of drainage systems for future precipitation extremes. Within the RegIKlim (Regional information for action on climate change) consortium, the NUKLEUS (Actionable local climate information for Germany) project will not only provide climate information at the local scale, but also to co-develop interfaces between climate and impact models, in order to fulfil the needs of the impact modelling community as good as possible. Within the RegIKlim consortium, the impact modelling community is organised in six “model regions” across Germany, which cover a wide range of geographical and socio-economic conditions.</p><p>For the NUKLEUS project, the baseline will be the latest generation of EURO-CORDEX downscaled CMIP6 simulations, which will be further refined to roughly 3 km horizontal resolution and 30-year time-slices for Germany with convection-permitting climate models (ICON CLM, COSMO-CLM, REMO-NH) and statistical-dynamical downscaling approaches. A detailed analysis on the performance of the multi-model mini-ensemble is planned to assess the quality of the provided data. At the interface to the users, we will follow three different approaches to provide usable climate information at the kilometer-scale. One is to provide easy-access to data and post-processing opportunities using the FREVA system. FREVA offers various access-levels from shell to web-based, which serves different levels of user-expertise. In addition, it provides a transparent way of post-processing data by workflow sharing mechanisms. The second one is to develop appropriate additional downscaling methods for the “last mile” where needed. For this “last mile”, we will apply dynamical and statistical methods such as urban climate models and/or weather generators. With the third approach we explicitly aim at integrating a collected user-feedback into the regional modelling systems used within NUKLEUS. Specifically, we intend to identify and incorporate data processing that is best done during the simulation permanently into the models. Examples are wind speeds at rotor heights of windmills or high frequency precipitation sums. NUKLEUS is a contribution to the German research program RegIKlim funded by the Federal Ministry of Education and Research (BMBF).</p>

A Method for Creating Product Social Impact Models of Engineered Products

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Phillip D. Stevenson ◽  
Christopher A. Mattson ◽  
Eric C. Dahlin
Keyword(s):  
Social Impact ◽  
Health And Safety ◽  
Social Impacts ◽  
Impact Categories ◽  
The Social ◽  
Impact Indicators ◽  
Mexico Border ◽  
And Performance ◽  
The Impact ◽  
Impact Models

AbstractAll products impact the lives of their users, this is called social impact. Some social impacts are commonly recognized by the engineering community, such as impacts to a user’s health and safety, while other social impacts can be more difficult to recognize, such as impacts on families and gender roles. When engineers make design decisions, without considering social impacts, they can unknowingly cause negative social impacts. Even harming the user and/or society. Despite its challenges, measuring a program’s or policy’s social impact is a common practice in the field of social sciences. These measurements are made using social impact indicators, which are simply the things observed to verify that true progress is being made. While there are clear benefits to predicting the social impact of an engineered product, it is unclear how engineers should select indicators and build predictive social impact models that are functions of engineering parameters and decisions. This paper introduces a method for selecting social impact indicators and creating predictive social impact models that can help engineers predict and improve the social impact of their products. As a first step in the method, an engineer identifies the product’s users, objectives, and requirements. Then, the social impact categories that are related to the product are determined. From each of these categories, the engineer selects several social impact indicators. Finally, models are created for each indicator to predict how a product’s parameters will change these indicators. The impact categories and indicators can be translated into product requirements and performance measures that can be used in product development processes. This method is used to predict the social impact of the proposed, expanded U.S. Mexico border wall.

Fracture in Taylor Rod Impact Test Specimens

2010 ◽  
Author(s):  
Sachin S. Gautam ◽  
Ravindra K. Saxena ◽  
P. M. Dixit
Keyword(s):  
Ductile Fracture ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Outer Edge ◽  
Impact Surface ◽  
Mechanics Model ◽  
Contact Impact ◽  
Impact Problems ◽  
The Impact ◽  
Aisi1045 Steel

High velocity contact-impact problems are of great interest in industries related to aerospace, mechanical and civil engineering. Ductile fracture often occurs in such applications. Taylor rod impact tests are used as experimental and numerical tests for determining the mechanical behaviour of materials subjected to high strain rates. At sufficiently high velocities, a significant plastic deformation leading to fracture is observed. In this paper, ductile fracture in Taylor rod made of AISI1045 steel is simulated using a continuum damage mechanics model. Simulations are performed for the velocity of 250 and 300 m/s. It is observed that, at lower velocities, tensile cracks are observed at the outer edge of the impact surface. On the other hand, at higher velocities, the fracture is observed at the central axis (confined fracture) as well as at the outer edge leading to fragmentation. Both the results are consistent with the experimental results available in the literature.

Cognitive constraints in English lexical blending

2018 ◽  
Vol 25 (1) ◽  
pp. 142-173
Author(s):  
Daniel Kjellander
Keyword(s):  
Neighborhood Effects ◽  
Formation Process ◽  
Word Formation ◽  
The Other ◽  
Word Class ◽  
Transfer Effects ◽  
Cognitive Constraints ◽  
Growing Body ◽  
The Impact ◽  
Derivatives Of

Abstract The complex characteristics of lexical blending have long troubled mainstream word formation research to the extent that it has typically been considered a peripheral issue in linguistics. In recent years this has begun to change, and there is currently a growing body of evidence uncovering the intriguing nature of this word formation process. In the present study, underlying principles and usage-based aspects of lexical blends were examined. Analyses of derivatives of three matrix words, republican, liberal, and vegetarian, revealed the impact of three cognitive constraints on the use of lexical blends: schema transfer effects, neighborhood effects, and effects of the influence from morphological lexicalization. The first constraint fueled blend formation, while the other two displayed a hampering effect on the use of lexical blending. Furthermore, a study of the word class distribution in the datasets showed that there were significant differences in the grammar of lexical blending and compounding, respectively.

Dynamic Energy Absorption Performances of Rain Forest Vehicle (RFV) under Frontal Impact

2014 ◽  
Vol 67 (3) ◽  
Author(s):  
M. S. Othman ◽  
Z. Ahmad
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Loading ◽  
Rain Forest ◽  
Experimental Testing ◽  
Rigid Wall ◽  
Crash Analysis ◽  
Frontal Impact ◽  
Frontal Section ◽  
The Impact

This paper treats the crash analysis and energy absorption response of Rain Forest Vehicle (RFV) subjected to frontal impact scenario namely impacting rigid wall and column. Dynamic computer simulation techniques validated by experimental testing are used to carry out a crash analysis of such vehicle. The study aims at quantifying the energy absorption capability of frontal section of RFV under impact loading, for variations in the load transfer paths and geometry of the crashworthy components. It is evident that the proposed design of the RFV frontal section are desirable as primary impact energy mitigation due to its ability to withstand and absorb impact loads effectively. Furthermore, it is found that the impact energy transmitted to the survival room may feasibly be minimized in these two impact events. The primary outcome of this study is design recommendation for enhancing the level of safety of the off-road vehicle where impact loading is expected.   

Inertial Surveying Systems — Experience and Prognosis

1980 ◽  
Vol 34 (1) ◽  
pp. 41-53 ◽  
Author(s):  
K. P. Schwarz
Keyword(s):  
Gravity Field ◽  
Error Propagation ◽  
State Of The Art ◽  
Simulation Software ◽  
Propagation Process ◽  
Straight Line ◽  
Imperfect Knowledge ◽  
Quantitative Manner ◽  
Anomalous Gravity ◽  
The Impact

Initially, the principle of inertial positioning is introduced and extensive new data from the Ottawa test net are used to discuss the state of the art. Two major problems presently limit the accuracy of the systems used in production work: heading sensitivity and the imperfect knowledge of the anomalous gravity field. An initial analysis of the new data indicates that the first is a software problem rather than a hardware problem. It appears that positioning of points along an L-shaped traverse can be done with the same accuracy as along a straight line. The second problem is assessed in a quantitative manner using simulation software. The impact of future hardware improvements on the accuracy of positioning is studied by simulating the error propagation process.

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