24,919 research outputs found
A survey of partial differential equations in geometric design
YesComputer aided geometric design is an area
where the improvement of surface generation techniques
is an everlasting demand since faster and more accurate
geometric models are required. Traditional methods
for generating surfaces were initially mainly based
upon interpolation algorithms. Recently, partial differential
equations (PDE) were introduced as a valuable
tool for geometric modelling since they offer a number
of features from which these areas can benefit. This work
summarises the uses given to PDE surfaces as a surface
generation technique togethe
Turbocharger blade vibration: Measurement and validation through laser tip-timing
High Cycle Fatigue (HCF) of turbine blades is a major cause of failure in turbochargers. In order to validate changes to blades intended to reduce fatigue failure, accurate measurement of blade dynamics is necessary. Strain gauging has limitations, so an alternative method is investigated. A description of the tip-timing method is given, applied to turbocharger testing. The advantages and disadvantages of laser probes are assessed. Examples of output data and interpretation are presented and compared with computer simulation. It is shown that laser tip-timing technology gives a more complete view of turbine vibration than the alternative measurement system
A study of commercial vehicle brake judder transmission using multi-body dynamic analysis
YesBraking-induced forced vibration, known as brake judder in road vehicles, causes
dissatisfaction to drivers and passengers and also damage and possible early failure in components
and systems. In this paper, the transmission of judder vibration from the point of generation
(the brake friction pair) through the vehicle structure to the driver is investigated for the
particular case of a heavy commercial vehicle. The investigation uses a computer simulation
multi-body dynamic model based on the automatic dynamic analysis of mechanical systems
software to identify any characteristics of the vehicle suspension design that might influence
the vibration transmission from the wheel to the driver.
The model uses a simplified rigid chassis and cab to lump the chassis parameters, so that the
investigation can focus on the front axle/suspension design, which is a beam axle leaf spring
arrangement, and the rear axle/suspension assembly, which is a tandem axle bogie design.
Results from the modelling indicate that brake judder vibration is transmitted to the chassis
of the vehicle through a leaf spring `wind-upĀæ mode and a `walkingĀæ mode associated with the
rear tandem axle. Of particular interest is the longitudinal vibration transmitted through the
chassis, since this creates a direct vibration transmission path to the cab and driver. The simulation
results were compared with the previously published experimental work on the same
design of commercial vehicle, and agreement between the predicted and the measured
vibration characteristics and frequencies was found.
It is concluded that the rear suspension design parameters could affect the transmission of
brake judder vibration to the cab and driver and that a tandem rear axle offers some design
opportunity to control the transmission of brake judder vibrations from the wheel to the cab
and driver. Given that brake judder has so far defied all attempts to eliminate completely
from vehicle brake systems, this is potentially an important opportunity
Applying Science Models for Search
The paper proposes three different kinds of science models as value-added
services that are integrated in the retrieval process to enhance retrieval
quality. The paper discusses the approaches Search Term Recommendation,
Bradfordizing and Author Centrality on a general level and addresses
implementation issues of the models within a real-life retrieval environment.Comment: 14 pages, 3 figures, ISI 201
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