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首页> 外文会议>American Society For Engineering Education Annual Conference and Exposition >COURSE-RELATED ACTIVITIES FOR MECHANICAL VIBRATION IN THE ABSENCE OF A FORMAL LABORATORY
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COURSE-RELATED ACTIVITIES FOR MECHANICAL VIBRATION IN THE ABSENCE OF A FORMAL LABORATORY

机译：课程相关的机械振动活动在没有正式实验室的情况下

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The Engineering Technology (ET) program at Middle Tennessee State University has approximately 350 students. Our Mechanical Engineering Technology (MET) concentration was started in the fall of 2004 and currently it has 120 majors. All MET students are required to take several senior level courses including Mechanical Vibration. The author started teaching this course formally in the fall of 2006. Although Vibration is a lecture/lab course currently we do not have a lab due to budget restrictions and therefore, the author decided to include a relevant hands-on project and an industrial visit. The student teams are required to design, build and test a Helmholtz resonator. A Helmholtz resonator, which can be modeled as a spring-mass system, consists of a body (cavity) and a neck whose dimensions can be selected to tune the resonator to respond at a desired natural frequency. In the fall of 2007 student teams as well as the author built resonators using steel and aluminum. We used a laptop computer and a freeware (software) to test the resonators. The testing included pressing the resonator neck opening against our lower lip and quickly blowing once and simultaneously recording the time domain data. The freeware was useful in recording the time domain data but the frequency response was not good because it did not display a well-defined peak. Therefore, we could not compare the calculated and measured natural frequencies satisfactorily. In spring of 2009 the author received an internal grant to purchase the frequency analysis software, SpectraPlus. This software can perform an FFT on an existing audio wave file using the sound card in a pc or laptop. It also has the capability of recording and performing fast Fourier transform (FFT) in real time. It can generate colorful frequency response and 3-D surface (signal, time and frequency) plots in a matter of seconds. In the summer of 2009 the author calculated the frequency response using SpectraPlus for the fall of 2007 and 2008 time-domain data. All 2007 and 2008 resonators were built/tuned to respond at a natural frequency of 1000 Hz. The FFT results showed a well-defined peak consistently at the same but lower than the calculated value for all cases. This means the software is reliable and that some damping was present in the resonator. The damping could be due to the viscosity of air or the fabrication techniques used. We wanted to investigate this matter further. In the fall of 2009 each student team was asked to design three resonators to respond at 1000 Hz, for consistency and comparison with the earlier results, using different metals. The students learned to use SpectraPlus as part of the laboratory activity. They were able to obtain several time domain data and generate the frequency response and 3-D surface plots. Each team submitted a formal report on their resonator project which included introduction, design, fabrication, testing, and discussion of results. In addition to the Helmholtz resonator project the students were given a tour of a local industry which performs dynamic balancing of multi-disk rotors that are used to produce corn flour for cattle feed.
机译：田纳西州州立大学的工程技术（ET）计划大约350名学生。我们的机械工程技术（MET）集中在2004年秋季开始，目前有120名专业。所有会见的学生都必须采取几个高级课程，包括机械振动。提交人开始在2006年秋天正式教导这门课程。虽然振动是一项讲座/实验室课程目前我们没有守律师，但由于预算限制，因此，提交人决定将有关的实践项目和工业访问纳入。学生团队必须设计，构建和测试亥姆霍兹谐振器。可以以弹簧质量系统建模的亥姆霍兹谐振器由身体（腔）和颈部组成，其尺寸可以选择尺寸以调整谐振器以期望的固有频率响应。在2007年秋季的学生团队以及作者使用钢和铝建立了谐振器。我们使用了一台笔记本电脑和一个免费软件（软件）来测试谐振器。该测试包括按压谐振器颈部开口对我们的下唇并快速吹一次并同时记录时域数据。自由软件可用于录制时域数据但频率响应不好，因为它没有显示明确定义的峰值。因此，我们无法比较计算和测量的自然频率令人满意。 2009年春季，提交人收到了购买频率分析软件，SpectraPlus的内部补助金。该软件可以使用PC或笔记本电脑中的声卡在现有音频波文件上执行FFT。它还具有实时录制和执行快速傅里叶变换（FFT）的能力。它可以在几秒钟内产生彩色频率响应和3-D表面（信号，时间和频率）图。 2009年夏天，作者计算了2007年和2008年时间域数据秋季的SpectraPlus的频率响应。建立/调整所有2007年和2008年的谐振器以响应1000 Hz的自然频率。 FFT结果始终定义了良好的峰值，其相同但低于所有情况的计算值。这意味着软件是可靠的并且谐振器中存在一些阻尼。阻尼可能是由于空气的粘度或所用制造技术。我们想进一步调查此事。在2009年秋季，每个学生团队都被要求设计三个谐振器以在1000赫兹以1000赫兹响应，以便使用不同的金属与前面的结果进行一致性和比较。学生学会了使用SpectraPlus作为实验室活动的一部分。它们能够获得多个时域数据并生成频率响应和3-D表面图。每个团队在其谐振器项目上提交了正式报告，其中包括介绍，设计，制造，测试和结果讨论。除了Helmholtz谐振器项目外，学生们还参观了一个当地的行业，该行业执行了用于生产用于生产玉米面粉的多盘转子的动态平衡。

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