本研究計畫之目標，將運用一全新的適應性演化的演算法來找出最佳的左右特徵向量(eigenvector)組合，藉由這種技術來探討抑制結構振動與結構噪音的可行性。結構的振動與聲壓的放射可以由振動的模態(mode shape)來描述，而振動與噪音的響應大小，也同時與外界擾動的分布有關。換句話說，結構振動與噪音放射的大小，受到振動結構的右特徵向量(關係到結構模態)與左特徵向量(關係到系統抵抗擾動的能力)影響。右特徵向量指定的概念是模態的訂製(mode shape tailoring)，應用於振動控制的指定法則是藉由主動控制改變右特徵向量，使得其對應於重要區域(concerned region)之模態分量盡可能變小。應用於結構減噪方面，設計的法則是經由主動控制改變右特徵向量，以減小由其產生的模態放射(modal radiation)。左特徵向量指定的概念是抗拒外界的擾動，設計的概念是藉著主動控制改變左特徵向量，使其盡可能與外力分布向量(forcing vector)垂直。本研究計畫的基本概念將適應性地調整系統之左右特徵向量，其左右特徵向量將演化為最佳的組合，以改變結構的模態與抵抗擾動的能力，使得結構的振動與噪音可以有效抑制。本研究計畫將運用幾何解釋的概念發展一套適應性的演化演算法，來選擇最佳的左與右特徵向量。壓電致動器(piezoelectric actuator)將提供系統的回授控制。適應性演算法中之演化法則的基本概念將朝正交指數(orthogonality indices)與模態能量比例(modal energy ratio)(用於振動控制)或是模態放射指數(modal radiation indices)(用於噪音抑制)遞減的趨勢進行演化，藉此找出最佳的左右特徵向量組合。 ; The objective of this research is to investigate the feasibility of utilizing a novel adaptive evolution algorithm for optimally assigning eigenvectors to reduce structural vibration and acoustical radiations. The structural vibration and sound pressure radiation can be expressed in terms of a combination of vibration modes, where its magnitude is also a function of the external disturbance distribution. In other words, the vibration response and radiated sound pressure level depend on both the right eigenvectors (related to the structural mode shapes) and left eigenvectors (related to the system disturbance rejection ability) of the vibrating structure. The right eigenvector assignment is the concept of mode shape tailoring. The assigned criterion for vibration control is to alter the right eigenvectors through active action such that the modal components corresponding to the concerned region are as small as possible. For structural noise control purpose, the design criterion is to modify the right eigenvectors through active action such that the modal radiation from the mode shape of vibrating structure is minimized. The left eigenvector assignment is the concept of disturbance rejection. The design concept is to alter the left eigenvectors by active action so that they are as closely orthogonal to the forcing vector as possible. The basic idea of the proposed approach is to adaptively adjust both the right and left eigenvectors, so that the structure’s mode shape and capability of disturbance rejection can be modified for vibration control and noise reduction purposes. The adaptive evolution algorithm for choosing the left and right eigenvectors will be developed with geometric interpretation. The feedback control will be achieved through active action of piezoelectric actuators. The adaptation rule of the evolution algorithm is based on minimizing the orthogonality indices and modal energy ratio (vibration control purpose) or modal radiation indices (noise control purpose), such that the optimal left and right eigenvector set can be determined. ; 研究期間 9708 ~ 9807
