Takafumi Nakayama

Auto-Assembly of 3D Pipe Models Based on Assembly Drawings

Refrigerant pipes in outdoor air conditioning units link the compressor and heat exchanger. The pipes vibrate due to the compressor vibration, and high vibration may cause pipe breakage or other problems. This is why study of ways to reduce pipe vibrations is so important at the design stage. Vibration analysis technology (CAE) can be used to calculate the vibration amplitudes and stresses of pipes in order to design low-vibration pipes. In order to conduct vibration analyses, a 3D analytical model must be defined in a computer. Unfortunately the process of creating a 3D analytical model is so labor intensive that vibration analysis is not currently a part of design work. In order to automate the process of creating a 3D analytical model, an algorithm for 3D analytical model auto conversion based on a 2D drawing of a pipe has been developed. The 3D analytical model to which the vibration analysis is applied is often constructed from several smaller 3D analytical pipe models. Therefore, it is necessary to be able to assemble a large model from several smaller ones automatically. An algorithm has been developed to automate the assembly of 3D analytical models of pipes based on assembly drawings.

Operational Deflection Shape Analysis for Pipes using Experimental Displacement Excitation Funcions of Vibration Sources.

Refrigerant pipes in outdoor air conditioning units link the compressor and heat exchanger. The pipes vibrate due to the compressor vibration, and high vibration may cause pipe breakage or another problems. This is why the study of ways to reduce pipe vibrations is very important at the design stage. Vibration analysis technology can be used to calculate the vibration amplitudes and stresses in pipes in order to design low-vibration pipes. In order to create an accurate vibration analysis model, it is important to define correct excitation functions of the vibration source (i.e. compressor) in the vibration analysis model. The correct excitation functions can be defined by integrating the pipe acceleration functions twice. The pipe acceleration functions are measured by using piezoelectric accelerometer. Errors typically encountered in the low frequency range can be corrected by appropriate methods.