MECHENG 722代做、代写Java/Python编程

日期：2025-05-15 09:07

MECHENG 722: Engineering Vibrations

MECHENG 719: Advanced Engineering Vibrations

Lab B Report - Vibration Testing with Shaker

Introduction

In this report, you are required to process the vibration measurements that you took from shaker

test in Lab B. You can use the same method (circle fit) and m-files provided before to estimate

the natural frequencies and mode shapes with the measured accelerance and compare the results

with those obtained from hammer test in Lab A and Project A. You also need to discuss the effects

of various factors on frequency response function measurements (accelerance and transmittance)

using shaker test and digital spectral analysis.

Report

Present your results in a report. A formal report (abstract, introduction, conclusions etc.) is not

required. Your submission should be well presented, neatly laid out and easy to follow. Your

discussion should reveal a good understanding of factors that influence the vibration testing and

experimentally-derived estimates. Graphs should be properly labeled. Marks will be deducted for

poor presentation. There is no formal length requirement. The report is due on CANVAS (a single

PDF file upload) by 12 PM, Friday 23 May.

The report should include two parts related to two tests (accelerance and transmittance

measurements) you performed in Lab B.

Part 1:

1. A table comparing the theoretically predicted and experimentally estimated natural frequencies

from Project A, Lab A and Lab B for the first 3 modes of the steel cantilever beam.

Natural frequencies Theory (Project A) Experiment (Lab A) Experiment (Lab B)

f1 (Hz)

f2 (Hz)

f3 (Hz)

2. Two graphs comparing the theoretically predicted and experimentally estimated mode shapes

(scaled appropriately) from Project A, Lab A and Lab B for any two modes you choose. One

graph for each mode.

Note: Load the accelerance measured at the beam tip (“driving point” measurement) to estimate

the natural frequencies. Load the accelerance measured at different locations of the beam to

estimate the diameters of modal circles for two chosen modes, from which you can estimate

the mode shapes. Use the circle fit method and m-files provided before.

3. A written section about your observations and discussion on:

Similarities and differences between the theoretical and experimental results (i.e. Lab B vs

Lab A and Lab B vs Project A) and suggest possible reasons.

Effectiveness of H1 and H2 estimates for accelerance measurement and the effects of

windows.

Note: Extra relevant graphs should be included as evidence of your observation.

Part 2:

4. A graph comparing the transmittances of the aluminium cantilever beam measured by

controlled sine sweep test and random test.

5. A written section about your observations and discussion on:

The effect of random excitation level on the measurements, with the same window (i.e.

Hanning window).

The effects of windows on the measurements, with the same excitation level.

Note: extra relevant graphs should be included as evidence of your observation.

Lihua, 9 May 2025