EFFECT OF OPEN CRACK ON VIBRATION BEHAVIOR OF A FLUID-CONVEYING PIPE EMBEDDED IN A VISCO-ELASTIC MEDIUM

Abstract

IN THIS PAPER THE VIBRATION BEHAVIOR OF A FLUID-CONVEYING CRACKED PIPE SURROUNDED BY AN VISCO-ELASTIC MEDIUM HAS BEEN CONSIDERED. DURING THIS WORK, THE EFFECT OF AN OPEN CRACK PARAMETERS AND FLOW VELOCITY PROFILE SHAPE INSIDE THE PIPE ON NATURAL FREQUENCY AND CRITICAL FLOW VELOCITY OF THE SYSTEM HAS BEEN ANALYTICALLY INVESTIGATED. AN EXPLICIT FUNCTION FOR THE LOCAL FLEXIBILITY OF THE CRACKED PIPE HAS BEEN OFFERED USING PRINCIPLE OF THE FRACTURE MECHANICS. COMPARISON BETWEEN THE RESULTS OF THE PRESENT STUDY AND THE EXPERIMENTAL DATA REPORTED IN THE LITERATURE REVEALS SUCCESS AND HIGH ACCURACY OF THE IMPLEMENTED METHOD. IT IS DEMONSTRATED THAT THE EXISTENCE OF THE CRACK IN THE PIPE, DECREASES THE NATURAL FREQUENCY AND THE CRITICAL FLOW VELOCITY SO THAT THE SYSTEM INSTABILITY ONSETS AT A LOWER FLOW VELOCITY IN COMPARISON WITH THE INTACT PIPE. RESULTS INDICATE THAT THE FLOW VELOCITY PROFILE SHAPE INSIDE THE PIPE CAUSED BY THE VISCOSITY OF REAL FLUIDS, SIGNIFICANTLY AFFECTS THE CRITICAL FLOW VELOCITY OF BOTH INTACT AND FLUID-CONVEYING CRACKED PIPE. FOR INSTANCE, AS THE FLOW-PROFILE-MODIFICATION FACTOR DECREASES FROM 1.33 TO 1.015, THE DIMENSIONLESS CRITICAL FLOW VELOCITY OF INTACT CLAMPED-CLAMPED PIPE INCREASES FROM 5.45 TO 6.24.