Static Testing
Our company has extensive facilities and expertise in structural testing,
for both static and fatigue testing.
Overload frames, hydraulic actuators, servo-controlled
and pressure-controlled load application, test fixture design, strain gauge data acquisition
and deflection measurements are all among the tools and methods available to help test
the strength of your product.
Re-configurable overload frames allow efficient setup for your item. Multiple actuators,
load cells and “whiffle trees” (load distribution mechanisms) are used to apply the loads
to the test item.
Load control systems track the applied load and safely unload the test
item should excessive deflections or load tracking errors occur. Data can be continuously
recorded and data “snapshots” taken at prescribed loading increments.
Fatigue Testing
DTB has an extensive fatigue test laboratory capable of performing Coupon, Component
and Full Scale Fatigue Testing of various components. Over 100 major test fixtures
are available to test specific aircraft components. We also have the engineering
and design capability to design and fabricate specialized test fixtures to test
any type of component requiring fatigue testing.
WE have a centralized hydraulic
power unit capable of supplying 800 GPM of hydraulic fluid at 3,000 psi pressure.
DTB can perform constant amplitude or spectrum fatigue loading of components up
to 200 kips at frequencies up to 25 hertz depending on load and displacement requirements. We have the capability of applying both linear and angular displacements utilizing
linear and rotary hydraulic actuators. Comparison fatigue testing of OEM and alternate
source parts can also be performed to demonstrate equivalency of fatigue life.
Fatigue Life Prediction
Using strain life methods, stress life or load life methods, we can analyze your
product, develop a loading spectrum and make fatigue life predictions for your system.
The strain information can come from test data or from finite element modeling.
We can support field strain gauges and load measurements to provide data for these
analyses.
Damage Tolerance Analysis
DTB has conducted significant structural test and analysis programs that involve
damage tolerance principles and design. Crack growth coupon tests are used to determine the
effect of loading frequency and environment on crack growth parameters.
For
example, we can measure the crack growth rate of arresting gear during life extension tests. Then we would correlate the actual test results to analytical predictions
of damage tolerance. This kind of hybrid testing and engineering work is a DTB hallmark.
DTB utilizes AFGROW and other software
packages for analysis of structures for crack growth life. In conjunction with our
stress analysis programs. We have experience in conducting damage tolerance analysis
on aircraft antenna installations and equipment modifications.
Servo-Controlled Load Application
DTB utilizes Servo-Controlled linear or rotary hydraulic actuators to apply the
test loads or displacements during all static and fatigue testing. Load control
for fatigue applications is typically accomplished using Cyber computer controlled
servo feed back control systems or our new MTS 16-Channel AERO ST Structural Test Controller.
The MTS AERO ST Controller is a reconfigurable load control system that can conduct both static and fatigue test programs using the latest in structural test control software and algorithms. The Aero ST controller employs industry-standard hardware for easy upgrades and runs on Windows operating system. It has an intuitive graphical user interface, making it easy to set up and run.
The multi-tasking operating system allows you to define new tests, analyze past results and monitor active tests currently in process, all at the same time. Coupled with AeroPro Control and Data Acquisition Software allows the user to access synchronized control and data acquisition information in real-time from a single source.
The servo valves utilized on the hydraulic actuators
can be load controlled or displacement controlled dependent on the feed back used.
In all cases, the computer software controlling the test loads or displacements
are programmed to terminate the test if the parameters shift in excess of five percent
of the baseline settings.
These systems developed by DTB have been proven throughout
years of performance on both fatigue and static tests performed for military and
commercial customers. The Cyber servo-controllers are driven by durable Hewlett-Packard
UNIX based computers, which allow for flexibility in programming wave shapes, load
spectrums, and static load profiles. These systems are currently capable of 16 control
channels and are easily expandable as required.
Loads Development
We can work with your engineering staff to determine the actual, real world loading
conditions on your system. Using strain gauges, load calibrations, data recording
equipment and other instrumentation, the loading history is recorded.
Using statistical
methods a loading spectrum can be determined that expands the recorded data into
the full range of conditions. This information can be used in analytical life predictions
and for discrete tests.
If you have actual test data, we can work with you to “truncate” the spectrum and
weed out the conditions that do not affect the component. The leaner spectrum can
expedite testing, thus reducing time and expense.
Coupon Testing
DTB has extensive facilities and expertise in coupon/mechanical testing, for static as well as
constant amplitude and spectrum fatigue testing. DTB facilities include a static load Tinius Olsen,
two Instron test systems and two servo hydraulic MTS systems to perform several type of material,
hardware or component tests. The testing ranges can reach up to 120 kips Staticcally
and 22 kips (tension) dynamically.
Our reliable and accurate testing solutions are ideal for
advanced materials research, product development, quality
control, and manufacturing process optimization.
DTB can
investigate overload failure, fatigue fracture, tensile fracture and
compression buckling while providing total life, crack initiation and
crack growth data.
We also provide coupon programs for
environmental (high temp and low temp) and corrosion affects on
materials as well as surface finishes.
Coupon programs are normally low cost, simple to conduct, tests that permit the
evaluation of materials (or variations of materials), hardware or components. Coupon
programs can be used for metallurgical variations evaluation (i.e., the effect of
heat treatment and microstructure), alloy chemistry variations evaluation and coupon
tests can be adapted to evaluate specific types of surface finish, environmental
and corrosion conditions.
Strain Gauge Services
WE have experience with custom strain gaging of customer parts for obtaining accurate
strain data in support of structural and fatigue testing. Applications include most
materials such as aluminum, steel, alloys, titanium and fiberglass laminates. Our
technicians are trained in gauge selection, surface preparation, adhesive selection,
installation and wiring for all types of strain measurements.
Flight Test Support
We have the expertise for installing all types of transducers and recording equipment
for aircraft flight testing. The most recent test was conducted in Fort Worth, TX.
Numerous strain gauges and accelerometers were installed to acquire vibration and
strain data on a Cheyenne aircraft nose gear door.
Instrumentation and Data Acquisition
DTB has the capability of acquiring and recording 100+ strain measurements, 25+
deflection measurements and 30+ load measurements. This is accomplished with either
of two types of data acquisition systems which are Hewlett Packard VXI 75000 Series
hardware with HPVEE software or National Instruments SCXI hardware with LabVIEW
software or VTI Technology EX1629 Remote Strain Gage Measurement Unit integrated with the MTS 16-channel Aero ST Structural Test Controller.
Our engineers can quickly tailor software programs to meet customer requirements
for data recording and realtime display of data.