Structural Dynamic Characteristics Modification via Surface Grooving Technique: Modified Algorithm and its Result.

Abstract

Changing shape of structure for improving its dynamic characteristic has been mostly relied on engineer's experience and time consuming trial-and-error process. In order to develop a systematic method to change structure shape, surface grooving technique has been developed. In this work, the shape of base structure is modified to improve its dynamic characteristics such as natural frequencies via surface grooving technique. Grooving shape is formed by merging the neighboring small embossed elements after analyzing frequency increment sensitivities about all the surrounding emboss elements. As a result of Surface Grooving Technique, an optimum grooving shape was automatically obtained. In this technique, the initial grooving position starts from the element having highest modal strain energy then it expands into neighboring elements. The range of grooving area for checking its frequency sensitivities is restricted only to their surrounding elements to reduce its computation effort. In order to make the method be more computationally effective, the algorithm was modified. Omitting the low-valued modal strain energy among neighboring element, target domain can be reduced and computational efficiency is improved. The developed algorithm was tested with hard disk drive (HDD) cover to raise its natural frequency by giving some groove on its surface. To verify the algorithm, result of simply supported plate was compared with example of yamazaki's method. Also the grooved HDD cover design was manufactured using rapid prototyping and tested to prove the effectiveness of the surface grooving as SDM techniques.