Course code: wb1406

Course name: Experimental Mechanics
Course changed. See wb1406-05

This concerns a course 

ECTS credit points: 3

Faculty of Mechanical Engineering and Marine Technology

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 overall objective of experimental mechanics is to contribute towards the validation of proposed mathematical models of mechanical systems. The first part of the course focuses on measurements of static systems. The second part focuses on measurements of dynamic systems.

   Measurement of deformations of statically loaded structural systems yield information about stresses in the system. With strain gages, deformations are determined locally; while with optical techniques, deformations can be determined over a much larger part of the system.

   Time-varying displacements (and deformations) in structural systems in motion (dynamic systems) also give information about stresses and loads in the system. In addition, it gives information about the system transfer function. The availability of a system transfer function, especially one with modal interpretation, is useful and usually necessary for the prediction of system performance and also for the determination of system material properties.

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:     %