Dynamic Analysis of Large Multi-Degree-of-Freedom Systems
Transient and Steady State Creep Solutions
Fluid dynamics and heat transfer
Finite element modeling
Two- and Three-Dimensional
Transient and Steady-State
Statistical Data Analysis
Basic data management and statistics
Engineering component and system reliability analyses
Advanced methods to interpret inspection data
Monte Carlo simulation
Nonlinear regression and optimization
Survival analysis of time-to-failure data using Weibull models
and Baysian updating
Design and engineering
mechanics software
Cosmos/M
ANYSYS
Dyna 3D
CAEPIPE
Custom-written
Computational fluid dynamics
(CFD) software
CFDesign
EFD.Lab
Customized boiler modeling
Aptech Engineering Services, Inc. (408) 745-7000
During
the failure investigation process, the first step is a visit to
the incident site to gather facts and evidence relevant to the
failure
and to document the appearance of the site. Once we have obtained
and examined the evidence, we begin developing potential failure
scenarios. Information pertinent to these scenarios is often obtained
by searching available documents and the technical literature.
To further evaluate potential failure theories, engineering analysis & modeling is
generally performed.
The types of engineering
analyses used in our failure investigations include:
Material Failure (fatigue, creep, corrosion, plastic flow)
Special loading conditions evaluated in these analyses include:
Thermal
Pressure
Impact
Seismic
Vibration
Explosion
Stress Analysis of
a Steam Header Experiencing Thermal Shock
Finite Element Model of
Stresses
Caused by Denting a Float Ball
Initial analyses often employ closed
form, hand calculation methods to approximate structure
or fluid behavior. This approach serves two purposes. The first is
to provide an initial screening of potential failure modes and the
second is to serve as a check on later more sophisticated, and expensive,
computer models (finite element or finite difference). In some cases
the results from the closed form analytical approach are sufficient
to pin down the failure mode. However, in many cases the available
data is insufficient for this approach to be sufficiently accurate.
In these instances, we may be faced
with the following challenges: a very complex design; unknown history
of past designs and materials; incomplete operation and maintenance
records; and absence of key evidence. For these problems, the failed
item is simulated on a computer using “finite element” software.
Parametric models are often built in order to investigate the effects
of various component changes on the integrity of the structure. Parameters
used in these models include: geometry, material properties, loading
conditions, repairs, and fabrication defects.
APTECH’s library
of computer codes provides considerable flexibility in handling a
variety of modeling problems. We are always seeking the latest software
packages. This, coupled with in-house development of new and efficient
post-processing techniques, allows us to continually expand our capabilities.
Of course, the analysis is only as good as the person
doing it. In addition to the skill required to build an accurate
model, the analyst must be able to choose realistic input data
and boundary conditions. The analyst must then be able to tell
if the result is accurate and “real world.” APTECH’s analysts
have the ability to do both since they are hands-on, practicing
engineers with years of hardware experience in the field and in
the lab. Their “native feel” for hardware, equipment
and devices is a crucial value-added skill that they bring to our
clients.
This
page has examples of some of our past work. Please
click on the arrows to see brief clips of the models in action.
Boiler Model: APTECHcreated
a model of a boiler's superheater tubing to evaluate the effect
of changing combustion conditions on the backpass heat exchangers.
Pipe Flow Model
Radio telescope track
displacement model
Aptech Engineering
Services, Inc. Main office location is in Sunnyvale, California — in
the heart of Silicon Valley, San Francisco Bay Area. 601 W. California Ave.,
Sunnyvale, California 94086 and P.O. Box 3440, Sunnyvale, CA 94088 (408) 745-7000
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