1 Vibration Wave

GelombangDr. Cuk Imawan

Term 1, 2007

Dr. Cuk Imawan

Agustus 2008, Term 1


Term 1, 2007

Buku:1. The Physics of Vibrations and Waves, HJ Pain, 5th Ed2. Fundamentals of Vibrations and Waves, SP Puri

Pertemuan: 14 kaliKompetensi yang ingin dicapai:•Kemampuan Ilmial (analisis Fisika, Matematika)•Kemampuan kerja tim, komunikasi, tulis

Penilaian (range nilai 100): Tugas 40%Quiz 30%UAS 30%

Kriteria jangkauan nilai: sesuai SK RektorKetidakjujuran walaupun hanya sekali saja:

MenyontekMembiarkan diri disontek

Tugas samaNilai maksimum E


Term 1, 2007

Materi Kuliah:

1. Simple Harmonic Motion (SHM)2. Damped SHM3. The Forced Oscillator4. Coupled Oscillations5. Transverse Wave Motion6. Longitudinal Waves7. Waves on Transmission Lines8. Non-linear Oscillations

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Term 1, 2007

Materi Kuliah:

SHM

Damped SHM

Forced Oscl.

Wave

,V

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osilasi


Term 1, 2007

F = -sx, restoring force

Linear / non Linear Oscillations

F -sx, restoring force


Term 1, 2007

SHM


Term 1, 2007

Shock absorbers must absorb or dissipate energy. One design consideration, when designing or choosing a shock absorber is where that energy will go. In most dashpots, energy is converted to heat inside the viscous fluid. In hydraulic cylinders, the hydraulic fluid will heat up. In air cylinders, the hot air is usually exhausted to the atmosphere. In other types of dashpots, such as electromagnetic ones, the dissipated energy can be stored and used later.


Term 1, 2007

Seismograph


Term 1, 2007

Accelerometer


Term 1, 2007

Vibration-to-Electric MEMS Device

Mechanical vibrations are converted into electrical energy by using a MEMS variable capacitor. The variable capacitor consists of a 1.5cm-by-0.5cm silicon structure etched in a wafer of 500µm thickness.

Digital Integrated Circuits & Systems GroupMIT


Term 1, 2007


Term 1, 2007

Molecular Vibration-Rotation


Term 1, 2007

• Due to the peculiar conditions of the straits, several unique engineering solutions needed to be considered. The water depth reaches 65 m, the seabed is mostly of loose sediment, the seismic activity and possibility of tectonic movement is significant, and the Gulf of Corinth is expanding at a rate of about 30 mm a year. For these reasons, special construction techniques were applied. The piers are not buried into the seabed, but rather rest on a bed of gravel which was meticulously leveled to an even surface (a difficult endeavor at this depth). During an earthquake, the piers should be allowed to move laterally on the seabed with the gravel bed absorbing the energy. The bridge parts are connected to the pylons using jacks and dampers to absorb movement; too rigid a connection would cause the bridge structure to fail in the event of an earthquake. It was also important that the bridge not have too much lateral leeway either so as not to damage the piers. There is provision for the gradual expansion of the strait over the bridge's lifetime.

Rio-Antirio bridge


Term 1, 2007

Taipei 101

Thornton-Tomasetti Engineers along with Evergreen Consulting Engineering designed a 662[15][16] metric ton steel pendulum that serves as a tuned mass damper. Suspended from the 92nd to the 88th floor, the pendulum sways to offset movements in the building caused by strong gusts. Its sphere, the largest damper sphere in the world, consists of 41 layered steel plates, each with a height of 125 mm being welded together to form a 5.5-meter diameter sphere. [17] [18] Another two tuned mass dampers, each weighing 4.5 tons, sit at the tip of the spire. These prevent cumulative damage to the structure due to strong wind loads. [19]

Antenna/Spire 509.2 m (1670.60 ft), Roof 449.2 m (1473.75 ft), Top floor 439.2 m


Term 1, 2007

One Wall Centre (Vancouver) 48-storeys tall with a total height of 150 m

To counteract possible harmonic swaying during high winds, One Wall has a tuned water damping system at the top level of the building which consists of two specially designed 50,000 Imperial gallon[2] (227,000 L) water tanks. These tanks are designed so that the harmonic frequency of the sloshing of the water in the tanks counteracts the harmonic frequency of the swaying of the building.


Term 1, 2007

Stockbridge dampers on power lines


Term 1, 2007

Millennium Bridge (London)The bridge's movements were produced by the sheer numbers of pedestrians (90,000 users in the first day, with up to 2,000 on the bridge at any one time). The bridge opened on an exceptionally fine day, and it was included on the route of a major charity walk. The initial small vibrations encouraged (or even obliged) pedestrians to walk in synchronisation with the sway, increasing the effect even when the bridge was comparatively lightly loaded at the beginning of the day.As such the motion was not anticipated by the computational analysis of the bridge prior to construction. It is often thought that the unusually low profile of the suspension cables contributed to the problem, but an analysis by the structural engineer, Arup, shows that it can occur in any bridge, suspension or otherwise, which happens to have the appropriate resonant frequencies and is subjected to large crowds. After extensive analysis, the problem was fixed by the retrofitting of 37 fluid-viscous dampers (energy dissipating) to control horizontal movement and 52 tuned mass dampers (inertial) to control vertical movement. This took from May 2001 to January 2002 and cost £5m. After a period of testing the bridge was successfully re-opened on 22 February 2002, and as yet there have not been any noticeable severe vibrations.


Term 1, 2007

The John Hancock Tower in Bostonvibrates naturally at a frequency of 0.14 Hz.

The building is a 60-story, 790-foot-tall (241 meter). Two 300-ton weights sit at opposite ends of the 58th floor of the Hancock. Each weight is a box of steel, filled with lead, 17 feet (5.2 m) square by 3 feet (0.9 m) high. Each weight rests on a steel plate. The plate is covered with lubricant so the weight is free to slide. But the weight is attached to the steel frame of the building by means of springs and shock absorbers. When the Hancock sways, the weight tends to remain still... allowing the floor to slide underneath it. Then, as the springs and shocks take hold, they begin to tug the building back. The effect is like that of a gyroscope, stabilizing the tower. The reason there are two weights, instead of one, is so they can tug in opposite directions when the building twists. The cost of the damper was $3 million. The dampers are free to move a few feet relative to the floor. LeMessurier Consultants says the dampers are located in relatively small utility rooms at each end of the building, leaving most of the 58th floor usable.


Term 1, 2007

• The sensor principle is based on the detection of small mass changes that results from binding of an analyte to receptor molecules coupled to the active sensor surface. The propagation velocity of acoustic shear waves travelling through a guiding layer at the sensor surface is very sensitive to additional mass loading. Thus, the change of the velocity is a measure of small mass changes at the sensor surface. Shear waves are generated and detected by interdigital transducers (IDTs) on either side of the active sensor surface. Receptor molecules can be coupled to the active sensor area by standard bio-chemical protocols, providing specific binding-sites for bio-molecules, peptides or proteins.

•


Term 1, 2007

TUGAS

Belajar pada WikiPedia

http://en.wikipedia.org

Kata kunci: vibration, oscillation, wave


Term 1, 2007

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1 Vibration Wave

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