DTB uses a highly structured failure analysis-based approach for reliability improvements. Typically, the approach results in the development of a detailed root cause failure cascade (RCFC), which becomes the basis for developing reliability improvement recommendations.
Today’s high performance ballistic armor systems are configured as multi-component, multi-interface entities that can be thought of as multi-interface macro-composites.
During service, these configurations are subjected to a number of stresses, including extreme temperatures; thermal cycling; static, vibratory, and impact loads; moisture intrusion; and UV and sand and dust exposure. In many instances, one or more of these environmental or dynamics/vibration stresses are present simultaneously.
Most electric-powered railway transportation systems ineffectively recover electrical energy that has been lost through braking, nor do they provide for the effective reuse of energy from braking. Currently, the majority of subway and commuter rail vehicles brake by using a combination of electrical resistors and brake pads. These systems do not provide any method by which to capture or reuse this electrical energy, which is wasted as dissipated heat.
DTB has investigated the feasibility and application of on-train regenerative braking electrical storage systems. These systems could capture and reuse megawatt-hours (Mwh) of wasted braking energy on a daily basis.
DTB is a research partner with the New York City Transit (NYCT) and is currently performing research concerning energy usage and efficiency, as well as wheel/rail patch interaction. We have integrated, installed, and operated data acquisition on a revenue train, as well as analyzed energy utilization in other areas of interest.
Diminishing Aircraft Parts
Given the ever-increasing complexity, development cost, and prototype-to-production lead time to produce new, multi-role joint service aircraft, government and commercial entities are exploring new ways to extend the lives of their aging aircraft and to expand their roles and mission profiles. Many of these aircraft, although still mission capable, are several decades old.
As the service lives of these aircraft are extended, the demand for the supply of spare parts to support them increases. At this point, many of the OEMs have either ceased production, merged with or have been absorbed by larger companies or competitors, or have simply gone out of business. The result is a critical shortage of spare and repair parts to support and sustain aging aircraft.
DTB has the experience and technical expertise to address government and commercial industry concerns about diminishing aircraft spare and repair parts by providing research, reverse engineering, and prototype development services for out-of-production aircraft parts and assemblies.
Explosive Blast & Shock
DTB has extensive experience in developing controlled pressure wave and shock pulse tests, which can be associated with various types of explosive threats.
We can perform all levels of hammer shock testing to MIL-STD-901. We have also been at the forefront of developing customized shock pulse test equipment and techniques to replicate the increasingly hazardous effects associated with improvised explosive devices (IEDs) and other emerging explosive threats.
DTB’s most recent work has been centered around the development of repeatable and tunable simulated explosive shock pulse testing techniques and equipment. This capability aims to shorten the product development test cycle by significantly reducing the time and expense associated with live ordnance field trials.
Some of the products that have benefited from simulated explosive shock pulse testing include armor, vehicle structures, drive train, suspension systems, crew compartment equipment, personal protective equipment (PPE) for soldiers, and restraint systems.
Fatigue (HCF) Testing
High Temperature/High Cycle Fatigue (HCF) Testing
High Temperature Fatigue Testing:
DTB has run a number of high temperature fatigue test programs, including the testing of parts for military and commercial aircraft, tanks, trucks, and automobiles. These tests are performed on various stator, compressor, and turbine blades, which can be fatigue tested at extreme temperatures of 400⁰F-1,800⁰F. These tests are also conducted using a hydraulic actuator, which is attached to the end of the blade using a clamp ring.
The machines that run these tests were developed here at DTB. Our machines serve as an improvement over the shaker-based system used at the OEM, since the tests are controlled using the actuator’s internal linear variable differential transformer (LVDT) for displacement control.
HCF testing is performed on a vibration shaker. This type of testing consists of mounting the base of the blade to a vibration plate; carefully tuning it in the resonant frequency at the desired mode frequency; and raising the amplitude to achieve the required stress levels. Calibration of the strain gages is critical for this test, since the high strain levels quickly fatigue the strain gages. The entire test is then controlled based on the blade tip displacement.
HCF testing is often required to run at elevated temperatures, which requires suspending heaters above the shaker, as well as cooling the vibration plate to protect the shaker head.
Alloy Application Development
Our client wanted assistance with designing protocols to down-select from a suite of several new alloys. The end application was going to involve severe steel-on-steel (both about HRC 62) contact at high speeds.
DTB’s solution was to perform highly controlled coupon level tests – incorporating the tracking of thermal and damage profiles. The testing process yielded results that allowed for down-selection on the basis of microstructural analysis of damage and sub-damage zones. We also designed and performed component level high fidelity testing with contact-severity-sensing feedback loops to further enhance the selection data.
of Complex Assemblies
Automated Screening of Complex Assemblies
DTB’s client wanted to screen a large number (>100,000) of sealed assemblies to non-destructively determine the chemical composition of a powder mixture that was enclosed within multiple metallic containers of steel and brass. The accuracy had to be better than 0.25%, and the screening had to be performed automatically. Additionally, we had to implement the technology in less than four months.
The solution was to develop a screening algorithm that used the concept of a master X-ray image, to which all others were compared, which would eliminate geometric deconvolution requirements and establish a correlation between the chemical composition and X-ray attenuation – while developing methods to acquire highly consistent microfocus X-ray images.
Our client was looking for a technique to detect and quantify fiber defects, such as wrinkling and waviness, in continuous glass fiber in reinforced epoxy-matrix composites used in helicopter blades.
DTB’s solution was to use microfocus computed tomography (CT) with special beam hardening in order to detect low contrast fibers. We performed 3D reconstruction to understand the fiber defects in all orientations and to generate critical-orientation serial sections through the volume. We also performed physical serial sectioning and compared the sections to CT data in order to establish one-to-one correspondence for technique validation and POD estimation.