Data processing: measuring – calibrating – or testing – Testing system – For transfer function determination
Reexamination Certificate
2002-06-28
2003-12-30
Barlow, John (Department: 2763)
Data processing: measuring, calibrating, or testing
Testing system
For transfer function determination
C702S150000, C702S155000, C702S182000, C702S097000, C702S050000, C473S351000, C473S329000, C473S321000, C473S318000, C473S199000, C473S140000, C428S364000, C073S570000, C073S866000, C073S012130, C073S012040, C345S420000, C345S423000, 36, C703S007000
Reexamination Certificate
active
06671642
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of evaluating an energy loss of a golf ball. More particularly, the present invention is intended to visualize the energy loss generated in the interior of the golf ball not by making the golf ball as an experiment but by a simulation.
2. Description of the Related Art
The flight distance of the golf ball is one of its important performances demanded by a golfer. The golf ball that can fly a long distance gives the golfer a refreshing feeling and contributes to getting a high score. To increase the flight distance, it is necessary to improve the restitution performance of the golf ball.
Therefore in designing the golf ball, the restitution performance of the golf ball when it is hit is one of the main items that should be evaluated. Thus to improve the restitution performance of the golf ball, many proposals have been hitherto made.
Considered in one proposal is to pay attention to an energy loss generated in the interior of the golf ball when it is hit. More specifically, when a hitting object impacts (collides with) the golf ball, the golf ball deforms greatly and separates from the hitting object, thus generating a restitution. It is known that the restitution coefficient of the golf ball at this time is greatly affected by the energy loss generated in the interior of the golf ball when the hitting object collides with the golf ball.
It is also known that when the hitting object does not strike against the sweet spot of the golf ball, an energy generated at the time of the collision therebetween flees out of the golf ball and the energy is lost. The energy loss which occurs in the interior of the golf ball when the hitting object collides with the golf ball affects the flight distance of the golf ball greatly. Thus the information of the energy loss is useful for improving the restitution performance of the golf ball.
However, since it is very difficult to observe the interior of the golf ball at the time of the collision (impact) between the hitting object and the golf ball, it is impossible to evaluate the energy loss generated in the interior of the golf ball when the hitting object impacts the golf ball. Therefore it is impossible to estimate and observe a portion (for example, a portion of the cover of the golf ball or the center thereof) of the interior of the golf ball and the extent of the generated energy loss. That is, the conventional art is incapable of sufficiently utilizing the energy loss in improving the restitution performance of the golf ball.
In the conventional method of designing the golf ball, a material composing the golf ball is determined, the golf ball is manufactured as an experiment, and the manufactured golf ball is actually hit. In this manner, the restitution performance of the designed golf ball is evaluated. The conventional designing method has a problem that much cost and time are required in the trial manufacture.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-described problem. Thus, it is an object of the present invention to provide a method capable of evaluating an energy loss generated in the interior of a golf ball when an actual hitting object collides (impacts) with the golf ball to improve the restitution performance of the golf ball and facilitate designing thereof.
To achieve the object, the present invention provides a method of evaluating an energy loss of a golf ball, having the steps of dividing a golf ball model into a large number of elements composed of a large number of nodal points in the form of meshes; inputting a physical property of a material for the golf ball; executing a simulation by an analysis based on a finite element method, assuming that a golf club head collides with the golf ball; and computing a strain amount generated in the golf ball model at the time of the collision (first step);
outputting a stress and a strain component of each element of the golf ball model and coordinate values of the nodal points of each element; and momently computing a value of a stress and a strain of each of six components of each element (second step);
finding a relationship between the stress and the strain of each component of each element from the value of the stress and said strain of each of the six components; and computing energy loss values of each element (third step); and
computing the energy loss value for all elements included in the golf ball model; reading the computed energy loss value by a visualizing software; and visualizing the energy loss of said golf ball model (fourth step).
As described above, by visualizing and observing the state of the energy loss generated in the interior of the golf ball when the hitting object collides with the golf ball, it is possible to evaluate the energy loss affecting the restitution performance of the golf ball in a high extent. Thereby it is possible to obtain information useful for improving the restitution performance in designing the golf ball. Therefore it is possible to design the golf ball superior in its restitution performance.
By three-dimensionally visualizing and displaying the energy loss of each element computed by the above-described method, it is possible to estimate and observe the interior portion of the golf ball where the energy loss is generated and the extent of the generated energy loss. The energy loss means the loss of a deformation (hysteresis) of each component of each element.
Since a simulation is executed by using the finite element method, it is possible to save the cost and time necessary for trial manufacture and achieve designing of the golf ball having various constructions by using various materials in a short period of time.
A golf ball model is divided into a large number of elements composed of a large number of nodal points in the form of meshes; a physical property of a material for the golf ball is inputted; a simulation is executed by an analysis based on a finite element method, assuming that a golf club head collides with the golf ball; and a strain amount generated in the golf ball model at the time of the collision is computed.
In executing the analysis based on the finite element method, an initial condition is set on the golf ball model. More specifically, the initial condition includes the size, configuration, construction, and physical property of the golf ball model; and the speed, configuration, construction, and physical property of an object (for example, golf club head model) which collides with the golf ball model.
A stress and a strain component of each element of the golf ball model and coordinate values of the nodal points of each element are outputted; and a value of a stress and a strain of each of six components of each element are computed momently.
In a three-dimensional space, each of the strain and the stress is constituted of three components in a vertical direction and three components in a shear direction, namely, six components in total. Therefore in the simulation executed by the finite element method, the energy loss of each of the elements constituting the golf ball model is computed for the six components. Thereby it is possible to execute an analysis in almost the same state as that generated in the collision between the actual hitting object and the golf ball. Thus the simulation can be accomplished with high accuracy.
In executing the simulation by using the finite element method, the element coordinate system may be used as the coordinate system constituting the reference of the three components of the stress and the strain of each element of the golf ball model in each of the vertical and shear directions in a three-dimensional space. That is, coordinate values of the nodal points of each element necessary for an element coordinate conversion may be outputted; and a value of a stress and a strain of each of six components of each element in an element coordinate system may be computed momently. The coordinate axis moves owing to a rotary movement generated in eac
Miyamoto Kazuyoshi
Shiraishi Masaki
Barlow John
Bhat Aditya
Sumitomo Rubber Industries Ltd.
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