ERI: System Tautochronic Pendulum Vibration Absorbers for Next-Generation Propulsion Systems and Other Machinery

该工程研究启动（ERI）奖支持能够开发独特的振动和噪声控制技术的研究，以减少旋转系统的振动，包括直升机转子和广泛用于节油传统和混合动力汽车动力系统的内燃机曲轴，从而促进科学进步，促进繁荣和福利，并确保国防。该研究将为下一代电气化机械的离心摆振减震器（cpva）设计提供新的基础知识，该减震器有可能提高混合动力汽车和电动汽车的推进效率和驾驶体验。cpva由安装在转子上的钟摆组成，由系统旋转驱动，当适当调整时，可以有效地平滑运行过程中引起振动的扭转喘振问题。当前最先进的CPVA和转子系统的反调谐方法将导致降低振动修正性能为给定的吸收器质量。该项目将通过一种新颖的自慢调谐方法来解决这一挑战，该方法有可能实现更直接的调谐，而无需考虑稳定性问题，从而减少实现性能目标所需的额外传动系统惯性。该奖项还将支持社区外展和涉及行业合作的学生研究项目，以及电气化推进工程新课程的开发和多样化STEM劳动力的培训。本研究旨在为系统共时调谐方法做出基本贡献，该方法包括吸收器质量遵循的路径，该路径考虑了吸收器与基座（转子）的惯性耦合，并导致系统的恒定周期自由振动，与振幅无关。这种调谐方法及其对减振器设计的改进已在重力场中得到证实，但离心力场仍存在许多重要的科学问题和挑战。与重力场类似，从该振子的一般周期函数中可以得到离心场中等自慢调谐的条件，该周期函数是通过将微分方程转化为标准形式得到的，然后要求极角速度与极径向坐标无关。等自慢调谐条件一般由吸收器路径曲率半径的非线性微分方程组成，其解为系统等自慢运动路径。离心场的一个基本区别是振子系数取决于系统动量常数。由吸收器和转子运动组成，这种对系统动量的推广可以彻底改变顺序调谐的概念，其中系统的自慢路径预计将在所有动量水平上保持调谐，而不仅仅是转子速度，正如几十年来所理解的那样。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Engineering Research Initiation (ERI) award supports research that enables the development of unique vibration and noise control technologies to reduce vibrations in rotating systems, including helicopter rotors and crankshafts of internal combustion engines widely used in fuel-efficient conventional and hybrid electric vehicles powertrains, thereby promoting the progress of science, advancing prosperity and welfare, and securing the national defense. The research will generate new fundamental knowledge related to the design of centrifugal pendulum vibration absorbers (CPVAs) for the next-generation of electrified machinery that has the potential to improve both propulsion efficiency and driver experience for hybrid electric and electric vehicles. CPVAs consist of pendulums mounted on a rotor, driven by system rotation, and when properly tuned, can efficiently smooth problematic vibration-inducing torsional surging during operation. Current state-of-the-art overtuning approaches of a CPVA and rotor system will result in reduced vibration correction performance for a given absorber mass. This project will solve this challenge via a novel tautochronic tuning approach, which has the potential to enable more direct tuning without stability concerns, thereby reducing added driveline inertia required to achieve performance objectives. This award will also support community outreach and student research projects involving industry collaborations and the development of new curriculum in electrified propulsion engineering and training of a diverse STEM workforce. This research aims to make fundamental contributions to a system tautochrone tuning methodology, which consists of a path for the absorber mass to follow that accounts for the inertial coupling of the absorber to the base (rotor), and results in a constant period free vibration of the system that is independent of amplitude. This tuning methodology and its enhancements to vibration absorber design has been identified in a gravity field, but a number of important scientific questions and challenges remain for the centrifugal field. Similar to the gravity field, conditions for the tautochronic tuning in a centrifugal field will be obtained from a general period function for this oscillator that is derived by transforming the differential equation to a standard form, and then requiring that the polar angular speed is independent of the polar radial coordinate. The tautochronic tuning conditions will generally consist of a nonlinear differential equation for the radius of curvature of the absorber path, whose solution is the system tautochronic motion path. A fundamental difference in the centrifugal field is that the oscillator coefficients depend on the system momentum constant. Consisting of both absorber and rotor motion, this generalization to system momentum could revolutionize the concept of order-tuning, where a system tautochronic path is expected to remain tuned across all momentum levels, instead of just rotor speeds, as has been understood for many decades.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.