Acceleration, as addressed in MIL-STD-810G Method 513.6 (Department of Defense, 2009), is a load factor (inertial load or “g” load) that is applied slowly enough and held steady for a period of time such that the materiel has sufficient time to fully distribute the resulting internal loads to all critical joints and components.
The common methods used to expose equipment to a sustained acceleration load are centrifuge and track/rocket-powered-sled testing.
However, both methods impose limitations on AE equipment testing. For example, the costs required and the scheduling, planning, and coordination phases associated with the use of these types of test
facilities are often prohibitive. In some cases, centrifuges and track/rocket sleds may limit the orientations at which the test article can be mounted for testing. To maintain validity, all AE devices are tested under the same mounting configuration as intended for operational use. Finally, due to the often expensive and delicate nature of medical devices, insufficient inventories often prevent the use of these tests due to their somewhat destructive nature.
Because of the difficulties associated with physical dynamic testing, the ATB team initially turned to Finite Element Analysis (FEA) as the method of choice for meeting acceleration test requirements.
Recent technological advances in microcomputing and higher resolution graphics capabilities allowed complex systems to be modeled and simulated for both static and dynamic tests.
The FEA techniques were already used by others for various aircraft structures and devices. For example, Foster and Sarwade (2005) performed an FEA of a structure that attached medical devices to a litter. This structure was later approved as STF. Continuing on the same theme, Lawrence, Fasanella, Tabiei, Brinkley, and Shemwell (2008) studied a crash test dummy model for NASA’s Orion
crew module landings using FEA. Viisoreanu, Rutman, and Cassatt (1999) reported their findings for the analysis of the aircraft cargo net barrier using FEA. Furthermore, Motevalli and Noureddine (1998)
used an FEA model of a fuselage section to simulate the aircraft cabin environment in air turbulence. These and similar studies demonstrated the successful use of the FEA method to verify requirements
by analysis for an acceleration test.
Given the costs associated with dynamic testing, the ATB originally envisioned using the FEA method to alleviate budget and inventory concerns. To test this theory, the ATB employed FEA for testing various AE structures to meet the acceleration requirements and found some aspects of this method to be cost- and time-prohibitive.
Lessons learned from these studies are provided in the case-studies section. The various types of analysis and test methods raise questions as to what the correct decision process is for selecting the most appropriate method for STF testing of AE equipment.
The authors of this article describe the process developed and employed by the ATB for the acceleration testing of AE equipment since June 2008.
The ATB’s process has proven to be well suited for identifying the most appropriate test method—one that not only represents the most appropriate and effective test method, but also minimizes the use of available resources. This process includes testing both structurally simple and complex equipment and successfully introducing the use of the Equivalent Load Testing (ELT) method, which permits
the use of alternative testing approaches, such as pull testing and tensile testing.
We provide testing and certification services at Istanbul Technical University Marine Equipment Test Center (METC)
In all project test phases, starting from requirements to verification tests, unit tests, integration tests, environment tests, and final/acceptance testing, we can support you. We can plan and test mechanical products, electrical equipment and devices, composite and innovative materials/alloys, Hazardous Materials (HAZ-MAT) packaging, medical equipment, an many other type of products developed in field use in dynamic environments.
We provide test and evaluation training
at your location
at Istanbul Technical University (ITU) Maritime Faculty (ITMF) Campus
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Our test center, Marine Equipment Test Center (METC) is located in Tuzla, Istanbul. METC provides accredited services for testing prototypes for harsh environments, such as temperature, humidity, drop, tensite, loading, inside pressure, corrosion, etc. We perform tests according to ISO 17025. We are experienced in developing proposals with verification and validation activities. Whether you are developing a device or a piece of software, we are experienced in developing test plans, procedures, and reports. In short we manage your test project wşth a due diligence.
- Testing of Hazardous Material (HAZ-MAT) packages for transportation
(Product testing per ADR Agreement)
- Testing of Marine Equipment and Life Saving Equipment (LSA) (per IMO LSA Code)
- Short Training Courses on Test Planning and Documents, Test Standarts, Testing and Test Management
(Training on MIL-STD-810H, RTCA-DO-160G, MIL-STD-461G, and other standards)
- Vibration and Shock testing.
- Testing of military equipment per MIL-STD-810H (DOD/military test standards)
- Testing of equipment per RTCA-DO-160G (aviation test standards per EASA / SHGM)
- Tensile testing of metals, composites, alloys, straps, etc.
- Surface roughness
- Corrosion testing (MIL-STD-810H, RTCA-DO-160, and including the ASTM sample tests)
- Static load testing
The manager of the METC facility, Dr. Ismail Cicek, have long years of testing experties since 2000s. MIL-STD-810G, RTCA-DO-160, ADR agreement for testing of hazardous packaging materias for transportation, Life Saving Appliances (LSA) Code are some of the standarts that we are experienced with and we do have the labratory with test infrastructure. Recently, testing of big HAZMAT packages (Internmediate Bulk Container, IBC) capability was added.
Additionally, some verification activities can be done using analysis techniques. We can perform Computational Fluid Dynamics (CFD), Finite Element Analysis (FEA), Fluid-Structure Interference (FSI) analysis in design stage for design verification and optimization.
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