发动机排气歧管模态分析

Modal Analysis of Engine Exhaust Manifold

振动疲劳能够引起排气歧管的失效,发动机和车身的激励频率与排气歧管的固有频率相近,会产生共振,这种共振会增大排气歧管的振动幅度,导致其加速断裂破坏;模态分析作为研究结构振动特性的常用手段,其分析的核心内容就是确定固有频率、阻尼比及振型等模态参数;本文针对排气歧管进行模态分析的目的是为了获得排气歧管的固有频率,进而能够确定引起疲劳破坏的最大激励频率,避免发动机排气歧管共振情况的发生。

Vibration fatigue can cause the exhaust manifold to fail.The excitation frequency of the engine and the body is close to the natural frequency of the exhaust manifold,and resonance will occur.This resonance will increase the vibration amplitude of the exhaust manifold and cause its accelerated fracture and damage.Modal analysis is a commonly used method to study the vibration characteristics of structures.The core of its analysis is to determine the modal parameters such as natural frequency,damping ratio and mode shape.The purpose of the modal analysis of the exhaust manifold in this paper is to obtain the natural frequency of the exhaust manifold,and then to determine the maximum excitation frequency that causes fatigue damage,to avoid the occurrence of engine exhaust manifold resonance.