Aslinya ini merupakan thread yang saya lontarkan di milis civeng, sekaligus email pribadi saya kepada Prof. Bambang Suhendro, dosen Teknik Sipil UGM di bidang struktur, “dewa”nya metode elemen hingga dan tetek bengeknya seperti matriks, analisis dinamika, dan lain sebagainya. Sembari menunggu jawaban dari peraih Magna Cumlaude Michigan University pada jenjang S2 dan S3 tersebut, itupun kalau saya tidak salah kirim email ;), sementara tanggapan dari milis civeng juga masih sedikit, okelah saya publish saja pertanyaan saya. Barangkali pembaca sekalian bisa menanggapi.
Apakah benar Tacoma Bridge runtuh karena resonansi?Selama ini penyebab itulah yang selalu diutarakan kepada kami di Teknik Sipil UGM. Namun, saya membaca di Wikipedia English beberapa paragraf berikut :
“Flutter is a self-feeding and potentially destructive vibration where aerodynamic forces on an object couple with a structure’s natural mode of vibration to produce rapid periodic motion. Flutter can occur in any object within a strong fluid flow, under the conditions that a positive feedback occurs between the structure’s natural vibration and the aerodynamic forces. That is, that the vibrational movement of the object increases an aerodynamic load which in turn drives the object to move further. If the energy during the period of aerodynamic excitation is larger than the natural damping of the system, the level of vibration will increase, resulting in self-exciting oscillation. The vibration levels can thus build up and are only limited when the aerodynamic or mechanical damping of the object match the energy input, this often results in large amplitudes and can lead to rapid failure. Because of this, structures exposed to aerodynamic forces – including wings, aerofoils, but also chimneys and bridges – are designed carefully within known parameters to avoid flutter. It is however not always a destructive force; recent progress has been made in small scale (table top) wind generators for underserved communities in developing countries, designed specifically to take advantage of this effect.
In complex structures where both the aerodynamics and the mechanical properties of the structure are not fully understood flutter can only be discounted through detailed testing. Even changing the mass distribution of an aircraft or the stiffness of one component can induce flutter in an apparently unrelated aerodynamic component. At its mildest this can appear as a “buzz” in the aircraft structure, but at its most violent it can develop uncontrollably with great speed and cause serious damage to or the destruction of the aircraft.
In some cases, automatic control systems have been demonstrated to help prevent or limit flutter related structural vibration.
Flutter can also occur on structures other than aircraft. One famous example of flutter phenomena is the collapse of the original Tacoma Narrows Bridge.”
Begitulah. Berikut saya sertakan linknya.
Ada yang bisa membantu ? 🙂