VIBRATION OF ROAD BRIDGES UNDER MOVING VEHICLES: A COMPARATIVE STUDY BETWEEN SINGLE CONTACT POINT AND TWO CONTACT POINT MODELS

2017 ◽  
Vol 41 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Tanuja Vaidya ◽  
Animesh Chatterjee
Keyword(s):  
Damage Identification ◽  
Contact Point ◽  
Point Model ◽  
Contact Points ◽  
Bridge Span ◽  
Moving Vehicles ◽  
Vehicle Velocity ◽  
Dimensional Parameters ◽  
Single Contact Point ◽  
Single Contact

The study of dynamic response of bridges under the action of moving vehicles provides a tool for structural designing as well as damage identification. Bridge-vehicle interaction is generally modelled through single contact point for mathematical simplicity, although the interaction actually takes place through front and rear wheels. In the present work, dynamic deflection of the bridge modelled through two contact points is investigated for a range of vehicle velocity and wheel to wheel distance. It is observed that for wheelbase to bridge span ratio greater than a certain limit, two contact point model gives significantly different results particularly at higher velocity range. The results, presented in terms of non-dimensional parameters, can be used as a design monograph for any bridge-vehicle-velocity combination.

Manipulator Calibration Using a Single Endpoint Contact Constraint

2000 ◽  
Author(s):  
Marco A. Meggiolaro ◽  
Guglielmo Scriffignano ◽  
Steven Dubowsky
Keyword(s):  
Joint Angle ◽  
Contact Point ◽  
Force Sensor ◽  
Calibration Method ◽  
Measuring Devices ◽  
Contact Constraint ◽  
Point Forces ◽  
Calibration Techniques ◽  
Single Contact Point ◽  
Single Contact

Abstract Most manipulator calibration techniques require expensive and/or complicated pose measuring devices, such as theodolites. This paper investigates a calibration method where the manipulator endpoint is constrained to a single contact point and executes self-motions. From the easily measured joint angle readings, and an identification model, the manipulator is calibrated. Adding a wrist force sensor allows for the calibration of elastic effects due to end-point forces and moments. Optimization of the procedure is discussed. Experimental results are presented, showing the effectiveness of the method.

Supporting Mental Health in the Community: New Systems for General Practice

2006 ◽  
Vol 12 (2) ◽  
pp. 105 ◽  
Author(s):  
Anne Sved Williams ◽  
Jill Poulton
Keyword(s):  
Mental Health ◽  
Primary Care ◽  
Mental Health Problems ◽  
Contact Point ◽  
Single Point ◽  
South Australia ◽  
Point Of Entry ◽  
Ease Of Access ◽  
Single Contact Point ◽  
Single Contact

General practitioners (GPs) manage nearly one-third of Australians seeking help for mental health problems, and frequently express their need for consultant psychiatric support in this work. The introduction of new Medical Benefits Schedule Item Numbers 291 and 293 to provide "one-off" psychiatric assessments on referral from GPs offered the potential for providing this support, and a single point-of-entry scheme was organised to provide ease of access to appointments. The aims were to establish a single point of entry for psychiatrist assessment using Item 291, to evaluate the take-up rates of Item 291 in South Australia (SA) through this service and to evaluate the acceptability to GPs and psychiatrists of a psychiatric primary care consultation-liaison (c-l) model. Results were: 26 psychiatrists joined the project; 64 GPs referred 78 patients for assessment, providing 24% of the Australian take-up rate for Item 291, for 8% of the population; evaluation showed high approval ratings from GPs who particularly appreciated the single contact point; and positive evaluation by psychiatrists of the primary care c-l model. The conclusions were that a single contact point provided ease of access to psychiatrists for GPs; GP and psychiatrist groups evaluated Item 291 very positively; and consumer and carer evaluation are essential for further primary care c-l development.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

scholarly journals Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

2021 ◽  
pp. 146808742110080
Author(s):  
Jamshid Malekmohammadi Nouri ◽  
Ioannis Vasilakos ◽  
Youyou Yan
Keyword(s):  
High Speed ◽  
Contact Point ◽  
Cylinder Liner ◽  
Optical Methods ◽  
Engine Management System ◽  
Great Success ◽  
Ic Engine ◽  
Contact Points ◽  
Lubricant Flow ◽  
Cavitation Intensity

A new engine block with optical access has been designed and manufactured capable of running up to 3000 r/min with the same specification as the unmodified engine. The optical window allowed access to the full length of the liner over a width of 25 mm to investigate the lubricant flow and cavitation at contact point between the rings and cylinder-liner. In addition, it allowed good access into the combustion chamber to allow charged flow, spray and combustion visualisation and measurements using different optical methods. New custom engine management system with build in LabView allowed for the precise full control of the engine. The design of the new optical engine was a great success in producing high quality images of lubricant flow, cavitation formation and development at contact point at different engine speeds ranging from 208 to 3000 r/min and lubricant temperatures (30°C–70°C) using a high-speed camera. The results under motorised operation confirmed that there was no cavitation at contact points during the intake/exhaust strokes due to low in-cylinder presure, while during compression/expansion strokes, with high in-cylinder pressure, considerable cavities were observed, in particular, during the compression stroke. Lubricant temperatures had the effect of promoting cavities both in their intensity and covered ring area up to 50°C as expected. Beyond that, although the cavitation intensity increases further with temperature, its area reduces due to possible collapse of the cavitating bubbles at higher temperature. The change of engine speed from 208 to 800 r/min increased cavitating area considerably by 52% of the ring area and was further increased by 19% at 1000 r/min. After that, the results showed very small increase in cavitation area (1.3% at 2000 r/min) with similar intensity and distribution across the ring.

scholarly journals The macroscopic shape of assemblies formed from microparticles based on host–guest interaction dependent on the guest content

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takahiro Itami ◽  
Akihito Hashidzume ◽  
Yuri Kamon ◽  
Hiroyasu Yamaguchi ◽  
Akira Harada
Keyword(s):  
Molecular Recognition ◽  
Smart Materials ◽  
Self Assembly ◽  
Early Stage ◽  
Contact Point ◽  
Sodium Acrylate ◽  
Contact Points ◽  
Assembly Behavior ◽  
Small Clusters ◽  
Macroscopic Shape

AbstractBiological macroscopic assemblies have inspired researchers to utilize molecular recognition to develop smart materials in these decades. Recently, macroscopic self-assemblies based on molecular recognition have been realized using millimeter-scale hydrogel pieces possessing molecular recognition moieties. During the study on macroscopic self-assembly based on molecular recognition, we noticed that the shape of assemblies might be dependent on the host–guest pair. In this study, we were thus motivated to study the macroscopic shape of assemblies formed through host–guest interaction. We modified crosslinked poly(sodium acrylate) microparticles, i.e., superabsorbent polymer (SAP) microparticles, with β-cyclodextrin (βCD) and adamantyl (Ad) residues (βCD(x)-SAP and Ad(y)-SAP microparticles, respectively, where x and y denote the mol% contents of βCD and Ad residues). Then, we studied the self-assembly behavior of βCD(x)-SAP and Ad(y)-SAP microparticles through the complexation of βCD with Ad residues. There was a threshold of the βCD content in βCD(x)-SAP microparticles for assembly formation between x = 22.3 and 26.7. On the other hand, the shape of assemblies was dependent on the Ad content, y; More elongated assemblies were formed at a higher y. This may be because, at a higher y, small clusters formed in an early stage can stick together even upon collisions at a single contact point to form elongated aggregates, whereas, at a smaller y, small clusters stick together only upon collisions at multiple contact points to give rather circular assemblies. On the basis of these observations, the shape of assembly formed from microparticles can be controlled by varying y.

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.

Sign in / Sign up

Export Citation Format

Share Document