Three-Dimensional Quantification of Multi-Point Contact Loads During Lumbar Spinal Manipulation

2004 ◽  
Author(s):  
Maruti R. Gudavalli ◽  
Robert M. Rowell
Keyword(s):  
Spinal Manipulation ◽  
Force Plate ◽  
Three Dimensional ◽  
Point Contact ◽  
Time Data ◽  
Rib Cage ◽  
Contact Points ◽  
Contact Loads ◽  
Pelvic Support ◽  
Hand Contact

The objective of this study was to measure the complete three-dimensional loads at each of the support contacts namely both hand contacts, and the support loads at the rib cage and the pelvis during chiropractic treatments for low back pain. Two small force transducers were used to measure hand contact loads, and a specially instrumented force plate table was used for measuring support loads. A doctor of chiropractic delivered fourteen spinal manipulations to the lumbar spines of five subjects during a period of three weeks. The results showed that there are three dimensional loads at each of the four contact points. The loads at the thrusting hands reached as high as 382N. For the stabilizing hands the maximum loads were 160N. The support loads reached as high as 727N at the pelvic support and 660N at the rib cage support. This study reports for the first time data on the loads at each of the hand contact points and the support locations during chiropractic spinal manipulation.

scholarly journals Construction of Three-Dimensional Road Surface and Application on Interaction between Vehicle and Road

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Lu Yongjie ◽  
Huai Wenqing ◽  
Zhang Junning
Keyword(s):  
Quantitative Description ◽  
Three Dimensional ◽  
Point Contact ◽  
Estimation Method ◽  
Road Surface ◽  
Surface Model ◽  
Dynamical Process ◽  
Contact Points ◽  
Box Counting Dimension ◽  
The Impact

The quantitative description is given to three-dimensional micro and macro self-similar characteristics of road surface from the perspective of fractal geometry using FBM stochastic midpoint displacement and diamond-square algorithm in conjunction with fractal characteristics and statistical characteristics of standard pavement determined by estimation method of box-counting dimension. The comparative analysis between reconstructed three-dimensional road surface spectrum and theoretical road surface spectrum and correlation coefficient demonstrate the high reconstruction accuracy of fractal reconstructed road spectrum. Furthermore, the bump zone is taken as an example to reconstruct a more arbitrary 3D road model through isomorphism of special road surface with stochastic road surface model. Measurement is taken to assume the tire footprint on road surface to be a rectangle, where the pressure distribution is expressed with mean stiffness, while the contact points in the contact area are replaced with a number of springs. Two-DOF vehicle is used as an example to analyze the difference between three-dimensional multipoint-and-plane contact and traditional point contact model. Three-dimensional road surface spectrum provides a more accurate description of the impact effect of tire on road surface, thereby laying a theoretical basis for studies on the dynamical process of interaction of vehicle-road surface and the road friendliness.

Wheel/Rail Two-Point Contact Geometry With Back-of-Flange Contact

2007 ◽  
Author(s):  
Hiroyuki Sugiyama ◽  
Yoshihiro Suda
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Point Contact ◽  
Numerical Procedure ◽  
Contact Geometry ◽  
Light Rail ◽  
Contact Algorithm ◽  
Rail Vehicle ◽  
Contact Points ◽  
Contact Formulation

In this investigation, a numerical procedure that can be used for the three-dimensional analysis of wheel and rail contact geometry is developed using the constraint contact formulation. The locations of contact points are determined for given lateral and yaw displacements of a wheelset when one-point contact is considered for each wheel, while these two displacements are no longer independent when the two-point contact occurs. A systematic procedure for predicting the flange as well as the back-of-flange contact points is developed and used for the two-point contact analysis of wheel and rail. Numerical results that involve tread, flange, and back-of-flange contacts are presented in order to demonstrate the use of the contact algorithm developed in this investigation. In particular, the back-of-flange contact is discussed for assessing contact configurations of wheel and grooved rail in Light Rail Vehicle (LRV) applications.

Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

2020 ◽  
Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Good Prognosis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Group Function ◽  
Occlusal Contact ◽  
Maximum Deformation ◽  
Contact Points ◽  
Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

INTRA-SESSION RELIABILITY AND REPEATABILITY OF KNEE KINEMATICS IN SUBJECTS WITH ACL DEFICIENCY DURING STAIR ASCENT

2017 ◽  
Vol 17 (06) ◽  
pp. 1750092
Author(s):  
MARYAM HAJIZADEH ◽  
ALIREZA HASHEMI OSKOUEI ◽  
FARZAN GHALICHI ◽  
GISELA SOLE
Keyword(s):  
Knee Joint ◽  
Cruciate Ligament ◽  
Intraclass Correlation ◽  
Force Plate ◽  
Three Dimensional ◽  
Knee Kinematics ◽  
Compensatory Mechanisms ◽  
Joint Rotation ◽  
Stair Ascent ◽  
Acl Deficient

Analysis of knee kinematics and ground reaction forces (GRFs) is widely used to determine compensatory mechanisms of people with anterior cruciate ligament deficiency (ACLD). However, the practicality of the measurements is subject to their reliability during different trials. This study aims to determine the reliability and repeatability of knee joint rotations and GRFs in people with ACLD during stair ascent. Eight participants with unilateral ACL-deficient knees performed five trials of stair ascent with each leg. The movements were captured by VICON motion analysis system, and GRF components were recorded using force plate. Three-dimensional tibiofemoral joint rotations were calculated. Intraclass correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of multiple correlation (CMC) were calculated ACL-deficient legs showed lower absolute reliability during swing ([Formula: see text]–6.4) than stance phase ([Formula: see text]–2.2) for knee joint rotations. Moderate to high average measure ICCs (0.59–0.98), relative reliability, were achieved for injured and uninjured sides. The results also demonstrated high repeatability for the knee joint rotation ([Formula: see text]–0.97) and GRF ([Formula: see text]–0.99). The outcomes of this study confirmed the consistency and repeatability of the knee joint rotations and GRFs in ACL-deficient subjects. Additionally, ACL-deficient legs exhibited similar levels of reliability and repeatability compared to contralateral legs.

Intermeshing: A New Concept For Rapid Steel Erection

2019 ◽  
Author(s):  
Salam Al-Sabah ◽  
Debra Laefer ◽  
Linh Truong-Hong
Keyword(s):  
Structural Steel ◽  
Three Dimensional ◽  
Steel Bridges ◽  
Digital Manufacturing ◽  
Initial Analysis ◽  
Contact Points ◽  
Steel Connection ◽  
Welding Forces ◽  
And Robotics ◽  
Steel Cutting

<p>Three-dimensional intermeshing of steel enabled by advanced digital manufacturing holds the potential to radically change how steel bridges and buildings are connected. This paper presents the concept of the first universal structural steel connection in over 100 years. The proposed Intermeshed Steel Connection (ISC) exploits recent advances in steel cutting technologies and robotics to shape member ends precisely. This vastly reduces on-site bolting and welding. Forces are transferred through common bearing surfaces at multiple contact points. The new connection is designed to accelerate structural steel deployment and offer better disassembly options. This paper introduces the geometry, manufacturing, and initial analysis of the connection approach, which holds the potential to be robust, secure, scalable, and faster to erect.</p>

Characteristics of Eight Irish Dance LandingsConsiderations for Training and Overuse Injury Prevention

2021 ◽  
Vol 25 (1) ◽  
pp. 30-37
Author(s):  
Sarah Klopp Christensen ◽  
Aaron Wayne Johnson ◽  
Natalie Van Wagoner ◽  
Taryn E. Corey ◽  
Matthew S. McClung ◽  
...  
Keyword(s):  
Large Range ◽  
Force Plate ◽  
Three Dimensional ◽  
The Body ◽  
Peak Force ◽  
Warm Up ◽  
Dance Training ◽  
Rise Rate ◽  
Dance Movements ◽  
Reaction Forces

Irish dance has evolved in aesthetics that lead to greater physical demands on dancers' bodies. Irish dancers must land from difficult moves without letting their knees bend or heels touch the ground, causing large forces to be absorbed by the body. The majority of injuries incurred by Irish dancers are due to overuse (79.6%). The purpose of this study was to determine loads on the body of female Irish dancers, including peak force, rise rate of force, and impulse, in eight common Irish hard shoe and soft shoe dance movements. It was hypothesized that these movements would produce different ground reac- tion force (GRF) characteristics. Sixteen female Irish dancers were recruited from the three highest competitive levels. Each performed a warm-up, reviewed the eight movements, and then performed each movement three times on a force plate, four in soft shoes and four in hard shoes. Ground reaction forces were measured using a three-dimensional force plate recording at 1,000 Hz. Peak force, rise rate, and vertical impulse were calculated. Peak forces normalized by each dancer's body weight for each of these variables were significantly different between move- ments and shoe types [F(15, 15)= 65.4, p < 0.01; F(15, 15) = 65.0, p < 0.01; and F(15, 15) = 67.4, p < 0.01, respectively]. The variable years of experience was not correlated with peak force, rise rate, or impulse (p > 0.40). It is concluded that there was a large range in GRF characteristics among the eight movements studied. Understanding the force of each dance step will allow instructors to develop training routines that help dancers adapt gradually to the high forces experienced in Irish dance training and competitions, thereby limiting the potential for overuse injuries.

Spatial Kinematic Analysis of Threaded Fastener Assembly

2005 ◽  
Vol 128 (1) ◽  
pp. 116-127 ◽  
Author(s):  
Stephen Wiedmann ◽  
Bob Sturges
Keyword(s):  
Design Space ◽  
Compliant Mechanisms ◽  
Contact Point ◽  
Three Dimensional ◽  
Vertical Movement ◽  
Initial Contact ◽  
Geometric Problem ◽  
Intelligent Sensor ◽  
Contact State ◽  
Contact Points

Compliant mechanisms for rigid part mating exist for prismatic geometries. A few instances are known of mechanisms to assemble screw threads. A comprehensive solution to this essentially geometric problem comprises at least three parts: parametric equations for nut and bolt contact in the critical starting phase of assembly, the possible space of motions between these parts during this phase, and the design space of compliant devices which accomplish the desired motions in the presence of friction and positional uncertainty. This work concentrates on the second part in which the threaded pair is modeled numerically, and contact tests are automated through software. Tessellated solid models were used during three-dimensional collision analysis to enumerate the approximate location of the initial contact point. The advent of a second contact point presented a more constrained contact state. Thus, the bolt is rotated about a vector defined by the initial two contact points until a third contact location was found. By analyzing the depth of intersection of the bolt into the nut as well as the vertical movement of the origin of the bolt reference frame, we determined that there are three types of contacts states present: unstable two-point, quasi-stable two-point, stable three point. The space of possible motions is bounded by these end conditions which will differ in detail depending upon the starting orientations. We investigated all potential orientations which obtain from a discretization of the roll, pitch, and yaw uncertainties, each of which has its own set of contact points. From this exhaustive examination, a full contact state history was determined, which lays the foundation for the design space of either compliant mechanisms or intelligent sensor-rich controls.

Multi-Agent Form Closure Capture of a Generic 2D Polygonal Object Based on Projective Path Planning

2006 ◽  
Author(s):  
Pankaj Sharma ◽  
Anupam Saxena ◽  
Ashish Dutta
Keyword(s):  
Path Planning ◽  
Contact Point ◽  
Point Contact ◽  
Object Boundary ◽  
Actual Object ◽  
Contact Points ◽  
Correct Orientation ◽  
Novel Approach ◽  
Form Closure ◽  
Multi Agent

The study of multi-agent capture and manipulation of an object has been an area of active interest for many researchers. This paper presents a novel approach using Genetic Algorithm to determine the optimal contact points and the total number of agents (mobile robots) required to capture a stationary generic 2D polygonal object. After the goal points are determined the agents then reach their respective goals using a decentralized projective path planning algorithm. Form closure of the object is obtained using the concept of accessibility angle. The object boundary is first expanded and the robots reach the expanded object goal points and then converge on the actual object. This ensures that the agents reach the actual goal points at the same time and have the correct orientation. Frictionless point contact between the object and robots is assumed. The shape of the robot is considered a circle such that it can only apply force in outward radial direction from its center and along the normal to the object boundary at the contact point. Simulations results are presented that prove the effectiveness of the proposed method.

scholarly journals POINT-CONTACT SPECTROSCOPY OF MAGNESIUM DIBORIDE WITH DIFFERENT COUNTER-ELECTRODES

2003 ◽  
Vol 17 (27n28) ◽  
pp. 1405-1416
Author(s):  
A. I. D'YACHENKO ◽  
V. YU. TARENKOV ◽  
M. A. BELOGOLOVSKII ◽  
V. N. VARYUKHIN ◽  
A. V. ABAL'OSHEV ◽  
...  
Keyword(s):  
Andreev Reflection ◽  
Magnesium Diboride ◽  
Three Dimensional ◽  
Point Contact ◽  
Band Model ◽  
Counter Electrodes ◽  
Break Junctions ◽  
Point Contact Spectroscopy ◽  
Dc Current ◽  
Two Band Model

We report on tunneling and Andreev-reflection conductance spectra of 39 K superconducting magnesium diboride, obtained with Pb and Au counter-electrodes. Two distinct steps at close to 2.7 and 7.1 meV appear in a low-resistance metallic-type Au–MgB 2 junction characteristic, whereas a tunneling-like spectrum measured for the same junction, annealed by the application of DC current, exhibits only a rounded contribution of the larger gap. Junctions with a superconducting lead counter-electrode pressed into a bulk MgB 2 sample reveal two conductance peaks that are interpreted as the result of the formation of a highly-transmitting break junctions inside the magnesium diboride ceramic. Our results strongly support the two-band model with two different gap values on quasi-two-dimensional σ (7.1 meV) and three-dimensional π (2.7 meV) Fermi surface sheets of MgB 2.

Sign in / Sign up

Export Citation Format

Share Document