10 Conclusion
In this paper it has been shown that computational methods can be used
to calculate the vibratory and acoustic
properties of engine blocks and engine-shield systems.
Attention in the vibratory calculation is now concentrated on improving
the efficiency of model generation and improving computational efficiency.
There is also work on the
improvement of methods for estimating the excitation forces
involving advanced non-linear calculations of such phenomena
as the resonant coupling of vibrating crankshafts and cylinder blocks
which are separated by oil-films.
For the prediction of the acoustic properties, the SPIM and
the RIM are computationally much cheaper than the BEM. However, the
potential for accuracy and adaptability in the BEM is much
greater than that for the other methods. Hence, with steady
improvements in computer equipment and in the method itself, it
is likely that the BEM will prevail in the acoustic analysis
of engines.
In this application, the BEM for the acoustic analysis of the bare
engine block is at a much earlier development stage than is the FEM.
The BSEM for the acoustic analysis of a shielded engine
is at an even more immature stage of development.
However, it has been demonstrated in this paper how the BSEM may be employed.
The obvious next step in this work is to validate the method through
the comparison of computed with measured results on a real-world problem.
A culture of understanding can only evolve around any
design development technique when there is confidence in its computational
reliability and it is reasonably efficient.
Equipment for the measurement of the acoustic and vibratory properties has been
available for some decades and although improvements in the scope,
the reliability and the efficiency of such equipment are being made,
such a culture of understanding has developed over this time.
Computational techniques such as the FEM and BEM have become practical
in the engine noise area only over the last decade. Such a culture
of understanding for the application of the methods and the
interpretation of results will take time to develop fully. It is the
opinion of the authors that the FEM, BEM and BSEM, applied as
described in this paper, will become increasingly important in the
analysis of engine noise