scholarly journals Human-Structure Dynamic Interaction during Short-Distance Free Falls

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
E. Shahabpoor ◽  
A. Pavic
Keyword(s):  
Force Plate ◽  
Free Fall ◽  
Physical Contact ◽  
Contact Model ◽  
Dynamic Interactions ◽  
Agent Based ◽  
Sports Science ◽  
Impact Biomechanics ◽  
Contact Models ◽  
The Impact

The dynamic interactions of falling human bodies with civil structures, regardless of their potentially critical effects, have sparsely been researched in contact biomechanics. The physical contact models suggested in the existing literature, particularly for short-distant falls in home settings, assume the human body falls on a “rigid” (not vibrating) ground. A similar assumption is usually made during laboratory-based fall tests, including force platforms. Based on observations from a set of pediatric head-first free fall tests, the present paper shows that the dynamics of the grounded force plate are not always negligible when doing fall test in a laboratory setting. By using a similar analogy for lightweight floor structures, it is shown that ignoring the dynamics of floors in the contact model can result in an up to 35% overestimation of the peak force experienced by a falling human. A nonlinear contact model is suggested, featuring an agent-based modelling approach, where the dynamics of the falling human and the impact object (force plate or a floor structure here) are each modelled using a single-degree-of-freedom model to simulate their dynamic interactions. The findings of this research can have wide applications in areas such as impact biomechanics and sports science.

scholarly journals Biomechanical assessment of various punching techniques

2020 ◽  
Author(s):  
Jiri Adamec ◽  
Peter Hofer ◽  
Stefan Pittner ◽  
Fabio Monticelli ◽  
Matthias Graw ◽  
...  
Keyword(s):  
High Speed ◽  
Vertical Wall ◽  
Force Plate ◽  
Physical Parameters ◽  
Time Curve ◽  
Biomechanical Assessment ◽  
Sports Science ◽  
General Terms ◽  
Force Time ◽  
The Impact

Abstract Punches without the use of instruments/objects are a common type of body violence and as such a frequent subject of medicolegal analyses. The assessment of the injuries occurred as well as of the potential of the assault to produce severe body harm is based on objective traces (especially the documented injuries of both parties involved) as well as the—often divergent—descriptions of the event. Quantitative data regarding the punching characteristics that could be used for the assessment are rare and originate mostly in sports science. The aim of this study was to provide physical data enabling/facilitating the assessment of various punching techniques. A total of 50 volunteers took part in our study (29 males and 21 females) and performed severe punches with the fist, with the small finger edge of the hand (karate chop), and with the open hand with both the dominant and the non-dominant hands in randomized order. The strikes were performed on a boxing pad attached to a KISTLER force plate (sampling frequency 10,000 Hz) mounted on a vertical wall. The punching velocity was defined as the hand velocity over the last 10 cm prior to the contact to the pad and ascertained by using a high-speed camera (2000 Hz). Apart from the strike velocity, the maximum force, the impulse (the integral of the force-time curve), the impact duration, and the effective mass of the punch (the ratio between the impulse and the strike velocity) were measured/calculated. The results show a various degree of dependence of the physical parameters of the strikes on the punching technique, gender, hand used, body weight, and other factors. On the other hand, a high degree of variability was observed that is likely attributable to individual punching capabilities. In a follow-up study, we plan to compare the “ordinary” persons with highly trained (boxers etc.) individuals. Even though the results must be interpreted with great caution and a direct transfer of the quantitative parameters to real-world situations is in general terms not possible, the study offers valuable insights and a solid basis for a qualified forensic medical/biomechanical assessment.

scholarly journals The Effect of the Contact Model on the Design of Mechanical Systems

2012 ◽  
Author(s):  
M. R. Brake ◽  
D. S. Aragon ◽  
D. J. VanGoethem ◽  
H. Sumali
Keyword(s):  
Constant Coefficient ◽  
Degrees Of Freedom ◽  
Mechanical Systems ◽  
Constitutive Models ◽  
Coefficient Of Restitution ◽  
Rigid Body Dynamics ◽  
Contact Model ◽  
Elastic Plastic ◽  
Contact Models ◽  
The Impact

Impact is a wide-spread phenomenon in mechanical systems that can have a significant effect on the system’s dynamics, stability, wear, and damage. The simulation of impact in complex, mechanical systems, however, is often too computationally intensive for high fidelity finite element analyses to be useful as design tools. As a result, rigid body dynamics and reduced order model simulations are often used, with the impact events modeled by ad hoc methods such as a constant coefficient of restitution or a penalty stiffness. The consequences of the choice of contact model are studied in this paper for a representative multiple-degrees of freedom mechanical system. Four contact models are considered in the analysis: a constant coefficient of restitution model, two similar elastic-plastic constitutive models, and one dissimilar elastic-plastic constitutive model. The predictions of wear, mechanical failure, and stability are assessed for each of the contact models, and the subsequent effect on the system design is investigated. These results emphasize the importance of choosing a realistic contact model when simulations are being used to drive the design of a system.

The Role of Epistemic Uncertainty of Contact Models in the Design of Mechanical Systems

2013 ◽  
Author(s):  
M. R. Brake
Keyword(s):  
Constant Coefficient ◽  
Epistemic Uncertainty ◽  
Piecewise Linear ◽  
Mechanical Systems ◽  
Coefficient Of Restitution ◽  
Rigid Body Dynamics ◽  
Contact Model ◽  
Elastic Plastic ◽  
Contact Models ◽  
The Impact

Impact is a wide-spread phenomenon in mechanical systems that can have a significant effect on the systems dynamics, stability, wear, and damage. The simulation of impact in complex, mechanical systems, however, is often too computationally intensive for high fidelity finite element analyses to be useful as design tools. As a result, rigid body dynamics and reduced order model simulations are often used, with the impact events modeled by ad hoc methods such as a constant coefficient of restitution or penalty stiffness. The effect of epistemic uncertainty in the choice of contact model is investigated in this paper for a representative multiple-degree of freedom mechanical system. Five contact models are considered in the analysis: a constant coefficient of restitution model, a piecewise-linear stiffness and damping (i.e. Kelvin-Voight) model, two similar elastic-plastic constitutive models, and one dissimilar elastic-plastic constitutive model. The predictions of wear and mechanical failure are assessed for each of the contact models. The ramifications of the choice of the contact model for an optimization study of the system’s geometric design are also presented. These results emphasize the importance of choosing an accurate contact model when simulations are being used to drive the design of a system.

scholarly journals Making a meaningful impact: modelling simultaneous frictional collisions in spatial multibody systems

2015 ◽  
Vol 471 (2177) ◽  
pp. 20140859 ◽  
Author(s):  
Thomas K. Uchida ◽  
Michael A. Sherman ◽  
Scott L. Delp
Keyword(s):  
Multibody Systems ◽  
Contact Model ◽  
Practical Implementation ◽  
Computationally Efficient ◽  
Compression And Expansion ◽  
Contact Models ◽  
Current Impact ◽  
Physical Laws ◽  
The Impact ◽  
Impact Models

Impacts are instantaneous, computationally efficient approximations of collisions. Current impact models sacrifice important physical principles to achieve that efficiency, yielding qualitative and quantitative errors when applied to simultaneous impacts in spatial multibody systems. We present a new impact model that produces behaviour similar to that of a detailed compliant contact model, while retaining the efficiency of an instantaneous method. In our model, time and configuration are fixed, but the impact is resolved into distinct compression and expansion phases, themselves comprising sliding and rolling intervals. A constrained optimization problem is solved for each interval to compute incremental impulses while respecting physical laws and principles of contact mechanics. We present the mathematical model, algorithms for its practical implementation, and examples that demonstrate its effectiveness. In collisions involving materials of various stiffnesses, our model can be more than 20 times faster than integrating through the collision using a compliant contact model. This work extends the use of instantaneous impact models to scientific and engineering applications with strict accuracy requirements, where compliant contact models would otherwise be required. An open-source implementation is available in Simbody, a C++ multibody dynamics library widely used in biomechanical and robotic applications.

MAGNETIC FIELD IMPACT UPON TRIBOTECHNICAL CHARACTERISTICS OF PERMANENT CONNECTIONS IN RELATION TO FRICTION SHOCK ABSORBERS

2020 ◽  
Vol 2020 (10) ◽  
pp. 4-11
Author(s):  
Victor Tikhomirov ◽  
Aleksandr Gorlenko ◽  
Stanislav Volohov ◽  
Mikhail Izmerov
Keyword(s):  
Magnetic Field ◽  
Friction Factor ◽  
Physical Contact ◽  
Active Centers ◽  
Press Fit ◽  
Electro Magnetic Field ◽  
Investigation Methods ◽  
Electro Magnetic ◽  
The Impact ◽  
The Magnetic Field

The work purpose is the investigation of magnetic field impact upon properties of friction steel surfaces at fit stripping with tightness through manifested effects and their wear visually observed. On the spots of a real contact the magnetic field increases active centers, their amount and saturation with the time of dislocation outlet, and has an influence upon tribo-mating. The external electro-magnetic field promotes the increase of the number of active centers at the expense of dislocations outlet on the contact surface, and the increase of a physical contact area results in friction tie strengthening and growth of a friction factor. By the example of friction pairs of a spentonly unit in the suspension of coach cars there is given a substantiation of actuality and possibility for the creation of technical devices with the controlled factor of friction and the stability of effects achieved is also confirmed experimentally. Investigation methods: the fulfillment of laboratory physical experiments on the laboratory plant developed and patented on bush-rod samples inserted with the fit and tightness. The results of investigations and novelty: the impact of the magnetic field upon the value of a stripping force of a press fit with the guaranteed tightness is defined. Conclusion: there is a possibility to control a friction factor through the magnetic field impact upon a friction contact.

“New Normal”: Analisis Penerimaan Menggunakan Balance Score Card

2020 ◽  
Vol 3 (2) ◽  
pp. 396-402
Author(s):  
Maria Florentina Rumba ◽  
Margaretha P.N Rozady ◽  
Theresia W. Mado
Keyword(s):  
Higher Education ◽  
Higher Education Institutions ◽  
Normal Phase ◽  
Physical Contact ◽  
New Normal ◽  
Face To Face ◽  
Balance Score Card ◽  
Score Card ◽  
Pros And Cons ◽  
The Impact

Abstrak: Kebiasaan manusia berubah karena adanya wabah COVID-19, hal ini berpengaruh ketika manusia masuk ke dalam fase new normal. New normal diartikan sebagai keadaan yang tidak biasa dilakukan sebelumnya, yang kemudian dijadikan sebagai standar atau kebiasaan baru yang mesti dilakukan manusia untuk dirinya sendiri maupun untuk bersosialisasi dengan orang lain. Kebiasaan baru ini pun menimbulkan pro dan kontra seiring dengan dampak yang timbul. Lembaga pendidikan tinggi merupakan salah satu yang merasakan dampak penerapan new normal. Perkuliahan yang selama ini dilakukan secara online/daring, akan kembali dilakukan secara luring/tatap muka, dengan tetap menerapkan protokol COVID-19 seperti mengenakan masker, menjaga jarak, mengenakan sarung tangan, serta tidak melakukan kontak fisik seperti berjabat tangan. Masalah yang muncul bukan hanya kecemasan orang tua terhadap anak – anaknya, tetapi bagaimana lembaga pendidikan tinggi mengatur segala sumber daya yang dimiliki agar memenuhi standar penerapan new normal. penelitian ini bertujuan untuk mengetahui penerimaan  terhadap kondisi normal yang baru menggunakan Perspektif balance score card. Abstract: Human habits change because of the COVID-19 outbreak, this affects when humans enter the new normal phase. New normal is defined as a condition that is not normally done before, which is then used as a standard or new habits that must be done by humans for themselves or to socialize with others. This new habit also raises the pros and cons along with the impact arising with the new normal. Higher education institutions are the ones who feel the impact of implementing new normal. Lectures that have been conducted online / online will be re-done offline / face to face, while still applying the COVID-19 protocol such as wearing a mask, keeping a distance, wearing gloves, and not making physical contact such as shaking hands. The problem that arises is not only parents' anxiety about their children, but how higher education institutions regulate all available resources to meet new normal implementation standards. This study aims to determine acceptance of new normal conditions using the balance score card Perspective.

scholarly journals Factors Moderating the Impact of After Death Communications on Beliefs and Spirituality

2021 ◽  
pp. 003022282110291
Author(s):  
Jennifer K. Penberthy ◽  
Marieta Pehlivanova ◽  
Tevfik Kalelioglu ◽  
Chris A. Roe ◽  
Callum E. Cooper ◽  
...  
Keyword(s):  
Life Experience ◽  
Death And Dying ◽  
Emotional Reaction ◽  
Physical Contact ◽  
Fear Of Death ◽  
Future Directions ◽  
Life After Death ◽  
Moderating Factors ◽  
The Impact ◽  
Beliefs And Attitudes

After death communications(ADCs) are defined as perceived spontaneous contacts with living individuals by the deceased. This research presents on a subset of data from a recent large international survey of individuals who experienced ADCs and provided systematic information regarding these experiences. In our research we explore the impact of having an ADC on reported spirituality, religiosity, beliefs and attitudes about death and dying and also explore the moderating factors of this impact. We found that having an ADC was perceived as a positive life experience and that it was associated with a reduction in fear of death, belief in life after death and that the deceased could communicate with the living, and increased reported spirituality. Moderating factors include aspects of having or desiring physical contact with the deceased as well as perceiving some emotional reaction to the ADCs. Future directions for research exploration are also provided based on our findings.

scholarly journals Process Modeling and Simulation of Tableting—An Agent-Based Simulation Methodology for Direct Compression

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 996
Author(s):  
Niels Lasse Martin ◽  
Ann Kathrin Schomberg ◽  
Jan Henrik Finke ◽  
Tim Gyung-min Abraham ◽  
Arno Kwade ◽  
...  
Keyword(s):  
Raw Materials ◽  
Pilot Scale ◽  
Physical Models ◽  
Agent Based Simulation ◽  
Validation Data ◽  
Agent Based ◽  
Industrial Processing ◽  
Digital Twins ◽  
Product And Process ◽  
The Impact

In pharmaceutical manufacturing, the utmost aim is reliably producing high quality products. Simulation approaches allow virtual experiments of processes in the planning phase and the implementation of digital twins in operation. The industrial processing of active pharmaceutical ingredients (APIs) into tablets requires the combination of discrete and continuous sub-processes with complex interdependencies regarding the material structures and characteristics. The API and excipients are mixed, granulated if required, and subsequently tableted. Thereby, the structure as well as the properties of the intermediate and final product are influenced by the raw materials, the parametrized processes and environmental conditions, which are subject to certain fluctuations. In this study, for the first time, an agent-based simulation model is presented, which enables the prediction, tracking, and tracing of resulting structures and properties of the intermediates of an industrial tableting process. Therefore, the methodology for the identification and development of product and process agents in an agent-based simulation is shown. Implemented physical models describe the impact of process parameters on material structures. The tablet production with a pilot scale rotary press is experimentally characterized to provide calibration and validation data. Finally, the simulation results, predicting the final structures, are compared to the experimental data.

scholarly journals Integrated IEW-TOPSIS and Fire Dynamics Simulation for Agent-Based Evacuation Modeling in Industrial Safety

Safety ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 47
Author(s):  
Wattana Chanthakhot ◽  
Kasin Ransikarbum
Keyword(s):  
Emergency Evacuation ◽  
Industrial Sector ◽  
Industrial Safety ◽  
Dynamics Simulation ◽  
Entropy Weight ◽  
Fire Dynamics ◽  
Evacuation Simulation ◽  
Evacuation Modeling ◽  
Agent Based ◽  
The Impact

Emergency events in the industrial sector have been increasingly reported during the past decade. However, studies that focus on emergency evacuation to improve industrial safety are still scarce. Existing evacuation-related studies also lack a perspective of fire assembly point’s analysis. In this research, location of assembly points is analyzed using the multi-criteria decision analysis (MCDA) technique based on the integrated information entropy weight (IEW) and techniques for order preference by similarity to ideal solution (TOPSIS) to support the fire evacuation plan. Next, we propose a novel simulation model that integrates fire dynamics simulation coupled with agent-based evacuation simulation to evaluate the impact of smoke and visibility from fire on evacuee behavior. Factors related to agent and building characteristics are examined for fire perception of evacuees, evacuees with physical disabilities, escape door width, fire location, and occupancy density. Then, the proposed model is applied to a case study of a home appliance factory in Chachoengsao, Thailand. Finally, results for the total evacuation time and the number of remaining occupants are statistically examined to suggest proper evacuation planning.

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