Wind tunnel test of a sectional model has becoming popular in long span bridge design processes. It is convenient to analyze the bridge deck aeroelastic behavior. The model is simple in structure, hence it can reduce the wind tunnel test cost accordingly, compare to full model. However, the model geometrical shape as well as structural dynamic properties... Continue Reading →
Structure and Machine Natural Frequency
Every machine and structure has natural frequencies . if machines and structures are designed correctly, these natural frequencies will not affect the operation or reliability of the machines. In reality, however, a wide variety of fault condition are either caused by, or are affected by natural frequencies. It really is important to understand what they... Continue Reading →
Vibration Damages Towers (Case : Ferrybridge Cooling Towers Collapse)
On the 1st November 1965, during high winds, three out of a group of eight cooling towers at Ferrybridge 'C' Power Station collapsed, with the remaining towers sustaining severe structural damage. The towers, each 375 feet high, had been constructed closer together than was usual and had greater shell diameters and shell surface area then... Continue Reading →
Finite Element Method
Finite element method (FEM) is based on the idea of building a complicated structural object with simple element , or dividing a complicated structural object into small and manageable pieces (like a puzzle). The application of finite element can be found everywhere in everyday life, as well as in engineering. if you remember when you was... Continue Reading →
High Rise Building Vibration
Some of the causes of vibration that occurs in tall buildings. problems that most of us know is a vibration in buildings due to earthquake. but there are other causes that led to the building vibrate faster, this is caused by wind loads acting on the surface of the building.harmonic load due to wind can cause buildings to vibrate at a level of discomfort for the occupants of the building. many factors that affect the wind loading on tall buildings,including the shape of the building, the area where the building is in, and climate around the building. while the factors that affect a large vibration that occurs in the building except for the... Continue Reading →
Vibration Measurement setup for Modal Testing
Soft suspense Soft suspense Charge & Conditioning amplifier for shaker Charge & Conditioning amplifier for accelerometer Shaker MSA/DSA Computer Accelerometer Power Amplifier SG : Signal generator LC : load cell This setup is to measure Point FRF (Frequency Response Function) . The excitation force provided by shaker and measured by a load cell that exist in the shaker and the vibration response will be read by the accelerometer (accelerometer sensor is used as to result in inertance and an... Continue Reading →
Overview of Computational Fluid Dynamics Approaches
•Direct Numerical Simulation (DNS) –Theoretically, all turbulent (and laminar / transition) flows can be simulated by numerically solving the full Navier-Stokes equations –Resolves the whole spectrum of scales. No modeling is required –But the cost is too prohibitive! Not practical for industrial flows •Large Eddy Simulation (LES) type models –Solves the... Continue Reading →
Why vibration is important?
In many ways people can expect to obtain an ideal machine viewed from the angle of vibration , which is a machine that produces no vibration at all. Such an ideal machine will greatly save energy because of all the energy given to the whole machine will be used to perform the work alone, whether pumping a fluid, compressing the air, crushing paper etc. Without generating by products in the form of vibration. Apparently it is very unlikely because in terms of machining is not possible to get a very homogeneous material, fabrication machines without residual imbalance (residual unbalance) and rotating machinery moving and moving back and forth that does not cause friction with the other part. What is then seen as a result of the onset... Continue Reading →
Vibration Application (Modal Testing)
Modal testing can be applied for several purposes, including: • Diagnostic tools Modal testing can be used as a tool for diagnosing a failure of the structure, by knowing the characteristics of dynamic structure by using the modal testing, the modal testing can be known personally frequency of the structure, obtained when a big frequency change... Continue Reading →