**********************
Friday, May 24, 2002
11:00 a.m.
479 EBU-II
Samuel G.
Paikowsky, Sc.D
Geotechnical
Engineering Research Laboratory
Dept. of
Civil & Environmental Engineering
University
of Massachusetts
"The
Application of Grid-Based Tactile Pressure Technology to Discontinuous
Materials"
The behavior of discontinuous (discrete, granular) materials is an important factor in many disciplines. These materials display unique behavior in the form of volume change during shear and arching. The fundamental mechanism of arching relates to the ability of discrete units to transfer loads through interaction in a preferable geometry and thus to bridge between the zone (or point) of load application to the zone (or points) of reaction. These features result in a unique load transformation and stress distribution within discontinuous materials and on the boundary between them and solid surfaces. Accurate measurements of stress distribution are cardinal therefore for the understanding of the physical phenomena as well as the evaluation of design criteria and monitoring performance.
The existing methods of
evaluating stress distribution in a granular mass rely mostly on the use of
buried or surface mounted load cells. These measurements are difficult to
perform and are limited in their ability to capture the stress variation. A new
technology, which makes use of flexible, grid-based, tactile pressure sensors,
allows to measure stresses at a large number of points in proximity to one
another, hence providing a realistic normal stress distribution. Their
flexibility overcomes the effect of stiffness variation introduced by rigid
load cells and thus allows for measurements that better represent the existing
stress conditions. The application of the tactile pressure technology to
granular materials requires adaptation and calibration due do its innovative
principle of operation. The presented research addresses five subjects in soil
mechanics: (i) the effect of grain size on stress distribution measurement
(internal and along a boundary with a solid surface), (ii) the pressure dip
under the sand heap (iii) the contact stresses under a rigid strip footing,
(iv) the measurement of the stress distribution behind a model retaining wall,
and (v) the pressures developed on the front wall in a pull-out test. Interfacial Normal Stress Distribution (4mm
glass beads)
Awards/Honors
Lady Davis visiting professorship – Technion,
Israel Institute of Technology (2000/01 academic year).
Hogentogler - ASTM Paper of Outstanding Merit
Award 1996
NYI - National Science Foundation Young
Investigator Award 1993 - 1998
Engineering Foundation Award - 1990
Potter-Seltzer scholarship, MIT, 1988/89
Winner of the First Centrifuge Modeling
Prediction Contest, Dept. of Civil Engineering, M.I.T., 1985
M.Sc. with “Honors”
Best Teaching Assistant, Technion, 1981 and
1982
B.Sc. “Cum Laude.”
Current and Recent Sponsored Research
“Performance Monitoring and Modeling of
Sheeting and MSE Wall during Construction”, Route 44 Relocation Project
Section I, Massachusetts Highway Department
through GTR Inc., 5/02 – 9/03
”Innovative Load Testing Systems”
National Academy of Science, NCHRP 21-08; 6/00
- 10/02
”The Application of Grid-Based Technology to Discontinuous
Materials” National Science Foundation (NSF); 10/1/99 -
9/30/02; complementary support through Tekscan Corp. Boston, MA and the University of Massachusetts Lowell
**********************
Friday, May 10, 2002
12:45 p.m.
479 EBU-II
Larry J. Stephens
Senior Aeronautical Engineer
Skunk Works
Lockheed-Martin Aeronautics, Palmdale, CA
"The SAE Aero
Design Competition and How it Relates to Engineering Work at
Lockheed-Martin"
The SAE Aero Design
WEST Competition, hosted by Lockheed-Martin Aeronautics, Palmdale is a
competition requiring teams to build and fly a heavy lift radio control aircraft.
It will take place in Palmdale during June 7-9th. The team members get beyond
textbook theory by designing, building and testing the performance of a real
vehicle. The event brings students from around the globe in exciting and
intense competitions. Lockheed-Martin Corp will have University Relations
representatives at the competition to talk about job opportunities and to
accept resumes.
The seminar will talk
about the Aero Design Competition and how the tasking required by the
competition relates to the work done everyday by engineers in the aerospace
industry.
Larry Stephens has
more than 30 years experience in the Aerospace industry, the last 22 years as
an Aeronautical Engineer at Lockheed-Martin Aeronautics, Palmdale also know as
the famed “Skunk Works”. The
majority of that time he has been with the F-117A Stealth Fighter assigned as
Program Liaison Engineer to Flight Test and currently as a Senior Aeronautical
Engineer responsible for system integration for advanced programs. Prior to Lockheed
he was at Piper Aircraft, Vero Beach in the Research and Development Department
working on the development of the Tomahawk, Malibu, Seneca III, and several
other Piper aircraft.
For information: Edith Juanengo at (858) 534-3174