使用LS-DYNA进行NVH 和频域分析
课程目标(Objectives):

为解决汽车、航空、电子电器等行业中常见的振动、噪声及疲劳损伤等问题,LS-DYNA提供了一系列的频域内计算分析功能,包括频率响应函数、稳态振动与疲劳、随机振动与随机疲劳、反应谱分析,边界元和有限元声学等。本课程旨在为用户介绍这些频域内的计算功能,并探讨这些功能在汽车NVH等领域内的应用。课程包括理论讲解及操作练习。

本课程适合需要进行车辆NVH或者其他振动、噪声仿真计算(如飞行器振动噪声,发动机辐射噪声、机器的振动测试和模拟)的人员参加。本课程也对从事结构疲劳/耐久性/安全性分析的工程师和研究人员有用。

To solve the vibration, noise and fatigue problems which are common in automotive, aircraft and electronic product industries, a series of frequency domain analysis features have been implemented in LS-DYNA. They include FRF (frequency response functions), SSD (steady state dynamics) and fatigue, random vibration and fatigue, response spectrum analysis, BEM / FEM acoustics. The objective of this course is to introduce the frequency domain features to users, and explore the application of these features in vehicle NVH simulation, etc. The course includes theoretical lectures and hands-on exercises.

The course is recommended for engineers who need to run vehicle NVH or other vibration and acoustic simulation problems (e.g., aircraft / spacecraft vibro-acoustics, engine noise simulation, machine vibration testing and simulation). The course is also useful to engineers and researchers who work in the area of structural fatigue / durability /safety analysis.

课时:

一天

Duration:

One day

授课语言:

中文

Language:

Chinese

主要内容(Main Contents):


  • 介绍:

    LS-DYNA的频域分析功能和应用概述;NVH理论与试验技术
  • 频率响应函数:

    模态分析;模态叠加法;阻尼;节点力/合力频率响应函数
  • 简谐荷载下的稳态振动:

    求解强迫运动的大质量法;正弦扫描下的疲劳计算
  • 功率谱密度函数荷载下的随机振动:

    相关联和不关联的多激励荷载;声场荷载;重启动功能;预应力;随机疲劳(累积损伤比;Miner 规则;材料的应力-疲劳曲线;基于Steinberg三应力带的疲劳计算方法;Dirlik方法等)
  • 声学:

    Helmholtz公式;Rayleigh方法;Kirchhoff方法;节点边界元法;基于变分原理的非直接边界元法;基于矩阵的低阶模拟的快速边界元法;有限元声学;面板贡献分析;汽车消音器传递损失分析;半空间问题;振动声学问题;如何使用用户提供的速度/加速度边界条件;声学计算与时域、频域响应分析结合
  • 反应谱分析:

    输入地震波谱;模态综合方法(SRSS;CQC;Double Sum 方法等);多个荷载谱
  • 汽车NVH例子:

    白车身的频率响应函数;动态刚度与噪声传递函数;汽车辐射的噪声;车腔内的噪声;汽车消声器的传递损失分析
  • 练习:

    习题;频域关键字的设定;结果后处理;频域数据库文件
  • Introduction:

    Overview of LS-DYNA frequency domain features and applications; NVH Theory and lab testing technology
  • Frequency response functions:

    Modal analysis; Modal superposition method; Damping; Nodal force / Resultant force FRF
  • Steady state dynamics with harmonic loading:

    Large mass method for enforced motion
  • Random vibration with PSD loading:

    Correlated and uncorrelated multiple excitations; Acoustic waves; Restart feature; Pre-stress; Random Fatigue (Accumulative damage ratio; Miner’s rule; S-N fatigue curve; Steinberg’s three band method; Dirlik method, etc.)
  • Acoustics:

    Helmholtz equation; Rayleigh method; Kirchhoff method; Collocation / Variational indirect BEM; Fast BEM based on low rank approximation of matrices; FEM; Acoustic panel contribution analysis; Muffler transmission loss; Half-space problems; Vibro-acoustic problems; Running acoustic problems with user velocity / acceleration files; coupling of acoustics with transient / frequency response analysis
  • Response spectrum analysis:

    Input earthquake spectrum; Modal combination methods (SRSS, CQC, Double Sum method, etc); Multi spectra
  • Auto NVH examples:

    FRF for a trimmed BIW; Dynamic Stiffness and Noise Transfer Functions (NTF); Noise radiated by vehicles in motion; Noise in compartment; Muffler transmission loss
  • Workshop:

    exercises; setting up the frequency domain keywords; post-processing of results; new frequency domain databases
  • 培训课程专家(Instructor):


    崔喆/Zhe Cui 博士毕业于西安交通大学,2006 年~2009 年在肯塔基大学从事博士后研究,从 2011 年至今,在 LSTC 从事 LS-DYNA 中频域内振动和噪声等计算功能 的工程应用和用户技术支持。
    李利萍/Liping Li 博士,于2013年在美国加州大学伯克利分校机械工程系取得博士学位。此前,于2008年获得中国科学技术大学近代力学系学士学位。2013 年加入 LSTC,主要从事LS-DYNA中的转子动力学(Rotor Dynamics)和同几何分析 (Isogeometric Analysis)方面的计算功能开发和工程应用问题。