Course code: wb1406-05

Course name: Experimental Mechanics

This concerns a course 

ECTS credit points: 4

Faculty of 3mE

Section of Engineering Mechanics

Lecturer(s): Ernst, prof.ir. L.J.,Woerkom, dr.ir. P.Th.L.M. van

Tel.:  015 - 27 865 / 82792

Catalog data:

• Measurement of static strains and shape changes in structures using strain gages, photo-elastic method, thermo-elasticity, raster techniques, Moiré, holography, and laser-speckle techniques.
• Measurement of structural dynamics:
  properties of materials, viscous damping and structural damping, visco-elastic materials, modal analysis, frequency response, modal parameter identification, identification of frequency transfer functions.

Course year:

MSc 1^st year

Semester:

2A / 2B

Hours per week:

2

Other hours:

16

Assessment:

Written report

Assessment period:

2B, August

(see academic calendar)

Prerequisites (course codes):

Follow up (course codes):

wb2301, wb2303, tn3111wb

Detailed description of topics:

Part A: Statics of structures

Measurement of deformation and shape changes in structures, using different techniques: strain gages (types, utilization, errors), photo-elastic, thermo-elastic, raster methods with laser light (laser speckle interferometry) and with non-coherent light. Electrical and optical concepts are discussed and various techniques are compared. Case studies.

Part B: Dynamics of structures

Description of material properties. Selection of actuators and sensors. Systems with a single degree-of-freedom: identification of characteristic dynamic (modal) parameters using frequency sweep. Systems with multiple degrees-of-freedom: modal analysis, modal frequencies, mode shapes, local peak analysis ("circle fit"), placement of multiple sensors and actuators, identification of modal parameters using frequency sweep. Influence of sensor dynamics. Alternative excitation techniques (impulsive; stochastic). Cases studies.

Course material:

• Course notes for Part A
• Course notes for Part B

References from literature:

• See the reference lists in the Course notes.

Remarks assessment, entry requirements, etc.:

The execution and analysis of  five to six laboratory experiments constitutes an integral and essential part of the course. The experiments are to be carried out in teams of two students, towards the end of the academic year (semester 2B).

Learning goals:

The student must be able to:

1. demonstrate understanding of the application of several appropriate measurement methods; specifically: strain gauges, photo-elastic methods, thermo-elastic methods, raster methods with coherent laser light (laser speckle interferometry), raster methods with non-coherent laser light

2. compare these methods and discuss their relative merits (in dynamic systems)

3. describe mathematically the response of a linear mass/spring/damper system in the time domain and in the frequency domain

4. extract modal parameters (resonance frequency, spring constant, damping ratio) from system response both in the time domain and in the frequency domain

5. describe mathematically the response of a linear multi degree-of-freedom system in the time domain and in the frequency domain

6. extract modal parameters (modal frequencies, modal gains, modal damping ratios) from system response both in the time domain and in the frequency domain

7. discuss relative merits of different excitation techniques (shaker with frequency sweep, impact hammer)

8. discuss relative merits of different sensing techniques (strain gauge, seismic mass, piezo crystal, electromagnetic induction, laser vibrometer

9. evaluate the influence of mass and dynamics of actuator and sensor (experiments, as part of a small team)

10. carry out static and dynamic experiments, analyze the data, and report his findings

Computer use:

Hardware and software for signal analysis of the data from the laboratory experiments.

Laboratory project(s):

Five or six laboratory experiments, with analysis and reporting and a concluding oral exam.

Design content:

Percentage of design:     %