Thesis-1998-Hocknell.pdf (7.2 MB)
Computational and experimental analysis of elastic deformation in impact
thesis
posted on 2013-09-10, 13:24 authored by Alan HocknellThis thesis presents new developments in the computational analysIs of sculptured
surface products and in non-contacting vibration measurements based on the laser
Doppler technique. The work is applied to the study of elastic deformation during
impact where a detailed measurement and analysis capability is demonstrated using the
golf impact as a principal example.
A study of quadrilateral finite element mesh generation on sculptiired surface product
families has shown that the versatility of an existing paving mesh generation algorithm
can be improved significantly by dividing the product geometry into an anatomy of
features and further subdividing primary features into smaller areas with four
curvilinear sides. The hollow golf club head is an example of a sculptured surface
product and is used to demonstrate the mesh generation difficulties which are
overcome using the proposed approach.
A computational analysis of a hollow golf club head under steady state dynamic
conditions and in impact with a golf ball is presented which is of greater accuracy and
superior detail to any previously reported. These tools are necessary for the
development of a greater understanding of the detailed mechanical behaviour during
impact in terms of energy transfer and 'feel' characteristics and are of importance to the
golf equipment industry.
Experimental validation of impact models is achieved through the introduction of a
system of measurements which is suited to the analysis of high-speed, short duration
impacts between lightweight bodies in which large elastic deformation occurs. A
wealth of short duration golf impact data is captured efficiently using laser Doppler
vibrometers and piezo-electric accelerometers.
When using remote, non-contacting transducers such as the vibrometer, whole body
translation of the target body causes the point on the target interrogated by the laser
beam to change during the impact. A displacement compensation technique is
introduced which permits close approximation of the vibration of fixed points on
bodies undergoing whole body translation using data recorded from remote
transducers. The technique is of additional importance in matching the available
experimental data to points of interest in a computational model of the body. The
improvement in data quality, relative to a single remote measurement, is quantified by
reference to both simulated and actual experimental data in the case of steady state
vibration and transient pulse propagation in impact.
The golf impact is one of an increasing number of applications to exceed the
measurement range of the available non-contacting instrumentation. Accordingly, the
first practical demonstration of the laser Doppler accelerometer, a new non-contacting
laser transducer which is directly sensitive to the acceleration of a target surface, is
reported. The instrument has several advantages including an easily adjustable working
range with effectively no upper measurement limit, straightforward operation and use
of low cost optical components. Practical issues in the successful isolation of the
particular optical beat frequency which carries the acceleration signal are descnbed and
recommendations for the future development of this important new instrument are
discussed.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Publisher
© Alan HocknellPublication date
1998Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough UniversityEThOS Persistent ID
uk.bl.ethos.263673Language
- en