May 28, 2009

Introduction to Dynamic Analysis of Caesar II

Introduction to Dynamic Analysis of Caesar II

Caesar II is one of the many software used piping.

In the calculation of the Stress Analysis piping system, the two methods of calculation:
1st Static Stress Analysis
2. Dynamic Analysis

The first, Static Analysis is a calculation that must be done if the "friends" include kategory the "critical" so that must be counted by using the Software, such as Caesar II or AUTOPIPE.

Static Analysis is memperhitungankan static load, which will override the pipe slowly so that the piping system so have enough time to receive, and distribute the load react earlier overlooks "body" pipes, to reach a balance. Here is the balance achieved at the time the number of Forces and moments are zero, and the pipe does not move.

On Dynamic Loads, the burden of rapid change that occurred over time, piping does not have enough time to digest the load, distributing overlooks the body, so balance is not achieved. As a result, the number of Forces and moments is not zero, pipe movement, and "Internal Loads induced" can be higher or lower than the load is received.

Is the need for a different analysis to determine and know how the response from the piping system when receiving a dynamic load.

Caesar II itself has some methods that can be used to it:
1st Natural Frequency Calculation: We know that all objects will vibrate if beaten. Bergetarnya objects always have a certain frequency. The amount of frequency that occur that is called natural frequency. Each object has a Natural Frequency. On the object, if the size of the amplitudo from yesteryear and frequency of vibration generated in the range of acceptable human being, the voice that caused the ear can be received by us.

In the case of piping system, when the vibration (Vibration), of course, piping system will produce a natural Frequency. The size of the Natural Frequency piping system is not allowed with the same or near the Operating Frequency of Equipment, which is piping system is connected. General Rule said: Natural Frequency piping system is higher than the Operating Frequency of Equipment is better and will not cause problems, compared with the Natural Frequency of a low Piping System

Caesar II is able to calculate the natural Frequency of a piping system, and then to check in with an Operating Frequency Equipment. If lower, then the effort should reduce the occurrence of Vibrasi in the piping system.

In Caesar II, the choice is to do the calculation Capital Natural frequencies or Capital Analysis, which conducted an analysis to determine the nature of a material when the vibration (Vibration)

2. Harmonic Analysis: To analyze the load of a "cyclic" is a recurring expense that comes regularly. This method is used to analyze the "fluid pulsation" on Reciprocating Pump line, or also due to analyze Vibrasi Rotating Equipment. The burden of going inserted as a "concentrated forces or dicplacements" on one or two points in the piping system. Stress happens checked against the full range of cyclic stress.
3. Response Spectrum Analysis: the burden is "transient impulse type loads."
There are two types, namely Uniform Inertial Loading: for example, is a seismic event caused "ground movement", and then translated to Caesar as displacement, acceleration, and velocity, where the movement is forwarded to the piping system through the pipe support, in the form of inertia loads (mass of system times the accelerations). Stress caused combined with Stress for Sustained compared with Occasonal Allowable Stress per ASME B31.3 Code.

And Single Point Loading: The Loads on Relieve Valve, Water Hammer Loads, Loads Slug Flow, Rapid Valve closure type loads, which cause a single impulse dynamic loads on a number of point in the piping system.

4. Time History Analysis: This is the most accurate method, using the numeric integration of a dynamic equation to simulate respond to the piping system throughout the period of the load in progress.

This method requires a lot of data, speed calculation, memory and time needed compared with other methods. So, if specifically requested by a client alias not paid, and other methods, such as Spectrum Analysis methode is quite accurate, ngapain we also use this method difficult.

The process of calculation of dynamic analysis requires that the system first analyzed the static (static analysis). After that, the new analysis is done dynamis with the new file and make modifications as necessary so that the purpose of analysis can get accurate results.

Written on Wednesday, April 9, 2008 by Donny

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