NTS News Center

Latest News in Testing, Inspection and Certification

NTS News Center - Latest News in Testing, Inspection and Certification

International Approvals Update: Taiwan BSMI

Recently, Taiwan BSMI has performed inspections on products in the market under BSMI DOC scheme to ensure the BSMI marking with license holder D # and the appropriate local license holder information is available.

It is required to contain the details of the license holder in Traditional Chinese on the product brochure, user manual or marketing packaging including the company name, address and phone number. Such marking and information needs to be implemented before the product goes to market.

Importers or distributors must have an authorization letter from the DOC license holder available in case of BSMI audit. It is optional for importers to add their info (name/address/phone) on the packages. The BSMI marking and compliance statement requirements remain the same.

For any further questions regarding this new development, please contact our NTS International Approvals Team at IATeam@nts.com.

Microbial Challenge Testing: Determine Fungicide Levels For Your Material Formulation

The Microbial Challenge Test is commonly employed to determine the effectiveness of fungicides used in many products such as paints, plastics, wood, fabrics, footwear, finishes, etc…

Once such test method comes from ISO 846 “Plastics – Evaluation of the action of microorganisms”. This method is specifically used to determine the threat from deterioration of plastics as a result of a direct microbial attack on nutritive substrates as well as an indirect attack from microorganisms fueled by contamination on the substrate.

From ISO 846 we will focus on Methods B:  Determination of Fungistatic Effects.

Fungistatic Effect: The antimycotic (antifungal) effect of an antimicrobial treatment which prevents a given material from being overgrown by fungi under moist conditions.

Specimens using fungicidal treatment are “challenged” by being exposed to a mixed spore suspension in the presence of a nutrient medium.  If the fungicidal treatment is ineffective, fungi can grow over and attack the specimen leading to eventual deterioration.

With an effective fungicide there will be no growth on the specimen and possibly no growth on the nutrient medium in the area directly surrounding the sample.  This clean area is known as the “zone of inhibition”.  The size of the zone of inhibition indicates the strength of the fungicide.Fungistatic Effect

The method above has proven to be valuable when experimenting with the percentage of fungicide to use in the material formulation.

At NTS Tinton Falls, we have the expertise to carry out microbial challenge testing to provide you with the peace of mind that your product will meet your customers’ expectations for life of the product. For questions, contact our laboratory manager Tom Borrelli via email at tom.borrelli@nts.com or call  732-936-0800. You can also simply request a quote with our quick form!

International Approvals Update – India BIS Amendment No. 2

Bureau_of_Indian_Standards_Logo.svgIndia BIS has established an Amendment No. 2 to IS 13252(Part1):2010 and the requirements are very similar to IEC 60950-1 A2. The current IS 13252(Part1):2010 (with amendment no. 1) is permitted until Dec 31st, 2016.

For the existing registered models, the manufacturers can choose any one base model for Amendment 2 testing and the test reports must show compliance to IS13252(Part1):2010 Amendment 2 requirements. Such test reports and the undertaking form need to be submitted to BIS before Dec 31st, 2016.

For any further questions please contact Caio Collet-Silva, NTS International Approvals Manager at 510-570-7585 or email IAteam@nts.com.

Open House – NTS Detroit

Detroit_TeamDetroit Open House

Come on out to the NTS Detroit open house event and get a first hand look at how our 42,000 square-foot facility can support your next testing program!

The Detroit team can help answer your questions regarding requirements, compliance and standards for a variety disciplines including those within the Aerospace, Defense, and Transportation industries. Our engineers have seen it all and can help you with anything ranging from electric motors and generators, to alternators and starters and everything else in between.

Don’t miss this opportunity for our NTS Detroit team to get to know you and your upcoming test programs.

We look forward to seeing you on Wednesday, June 22, 2016 and don’t forget to bring your business cards.

Click here for event details and to register today!

NTS offers CAD/FEA Modeling for Direct and Indirect Effects Lightning, Reducing Test Costs and Time

The NTS Lightning Technologies laboratory in Pittsfield, MA is now offering finite element analysis, allowing the performance of complex simulations that accurately model the interaction of lightning with a variety of aircraft and avionics components for our customers. This service is available to all of the customers of the 10 NTS facilities across the US offering direct and indirect lightning testing.

Lightning Testing Figure 2

Figure 1 – Current Distribution and Magnetic Field in Two Current Carrying Copper Conductors

By decomposing complex CAD-generated objects into meshable geometrical shapes, these models are able to accurately portray the lightning environment (current distribution, electric and magnetic fields, pressure waves, temperature variations, induced transients) on high fidelity renditions of real objects. Once the geometry is built, highly customizable material parameters, boundary conditions, and applicable physics interfaces (Maxwell’s Equations) are applied that generate a system of equations that is solved in COMSOL. With accurate representation of test object geometries, the solutions of these models allow for conducted and induced transients to be determined at any point in the model.

Figure 2 - Magnetic Field Penetration through Apertures on a Fuselage

Figure 2 – Magnetic Field Penetration through Apertures on a Fuselage

Utilizing simulation and modeling along with laboratory testing provides customers with a new, cutting edge way to obtain valuable test data that can reduce testing costs substantially. Making use of these models allows for the easy acquisition of difficult or impossible to obtain lab measurements (equipment limitations) without having to perform the test on an actual object. Once a model has been developed, a similar test is performed on a real piece of equipment in order to validate the model. Once the model has been validated, lightning attachment locations, cable routing configurations, and material characteristics (to name a few) are all easily modifiable to allow for many permutations of the test environment to be modeled. The results of these models can provide valuable design constraints and necessary test levels for certification. Additionally, once validated, these models can serve as a firm basis for similarity analyses for future design changes, providing the potential for a cost and schedule reduction to future programs.

Figure 3 - Magnetically Induced Voltage on Conductor inside Fuselage

Figure 3 – Magnetically Induced Voltage on Conductor inside Fuselage

For questions about our new finite element modeling and how it can be applied to your testing program or for any other lightning test related inquiries please contact our General Manager Mike Dargi at 413.499.2135 or Mike.Dargi@nts.com

NTS has 10 facilities across the US capable of performing your complex direct effects and indirect effects lightning testing. We are able to meet the full scope of RTCA DO-160 testing, as well as numerous other specifications with lightning requirements including MIL-STD-461/462, SAE ARP 5416A, and IEC 61400-24 (wind turbines). Contact us today to discuss your next test program.

Explicit Finite Element Modeling Capability Enables Pyrotechnic Shock Test Design at NTS

For our customers in the space launch industry the requirement to perform pyrotechnic shock testing in the course of qualifying major subsystems and critical components of a space craft or payload is often a daunting prospect. This is due to the uncertainty associated with achieving specified shock levels (expressed in terms of an acceleration based shock response spectrum, or SRS) in traditional ordnance induced tests.

Historically, NTS and its competitors have performed iterative “equalization” tests using mass models of the product to be tested, or non-functional parts, to arrive at a test design that is acceptable to both the testing facility and the customer prior to running the shock test on the hardware to be qualified. This can involve significant expenditure of both test scheduling resources and consumption of test fixture hardware until a test design is agreed upon. There is also the resulting problem of significant over-testing across wide frequency ranges to insure the chances of an under-test are minimized.

Ordnance induced pyrotechnic shock testing is performed using a small explosive charge to impart an intense and very short (microseconds in duration) impulse to a resonating plate. The resonating plate responds to this impulsive load by propagating elastic stress waves (while some localized plastic deformation on the plate beneath the explosive charge does occur) throughout its volume which then reflects off free surfaces creating a very complex three dimensional transient stress field. It is this complex transient stress field that imparts the shock acceleration time history to the shelf or other test fixture structure acting as the interface between the resonating plate and the unit being tested as shown in Figure 1 below.


Figure 1. Response of Pyroshock Test Resonating Plate to Explosive Charge Detonation

For the last couple of years, the engineering services group at NTS Dana Point, CA, in partnership with our test facilities that perform pyrotechnic shock testing, has employed an explicit finite element solver, LS-DYNA, to perform design and analysis of pyrotechnic shock testing for various customers. This approach allows NTS to evaluate a wide range of pyrotechnic shock test fixture design options, explosive charge quantity and placement, in combination with basic mass properties models of the customer’s test article, without consuming any hardware resources.

Recently, this unique capability was recognized by the selection of the NTS paper, “Modeling of Ordnance-Induced Pyrotechnic Shock Testing,” for the Henry Pusey Award (best paper) at the 84th Shock & Vibration Symposium in Atlanta, GA in 2013.  As shown in Figure 2 below, excellent agreement has been achieved between the modeling and simulation results.

Pyro Shock Testing Comparison Model

Figure 2. Comparison of Explicit FEA Predicted SRS with Test Data

Although the commercially available explicit finite element solver, LS-DYNA, is a great resource for performing the required analyses, the key enabler of this capability has been the rapid evolution in computing power at the PC desktop workstation level. For the modeling approach to serve in the role as a functional replacement for performance of iterative equalization testing to evaluate a variety of test fixture design concepts and explosive charge size and placement, the turn-around time for performing each test fixture design iteration using the explicit finite element based modeling approach must be on the scale of 30 minutes or less of wall clock time. Run times on this scale for these models are now routinely achieved at our facility in Dana Point, CA. This approach also allows for a considerably wider range of test fixture design concepts to be evaluated without any risk to the customer furnished test hardware, as the additional cost and schedule associated with fabricating and assembling each test fixture design iteration is absent.

Explicit finite element modeling techniques have traditionally served in the role of weapons design codes for the US DOD and DOE. It is now being recognized that these same techniques have wider application to non-defense industries ranging from automotive and aircraft crash test analysis to safety barrier design and aerospace pyrotechnic shock testing design may now be added to this list.

NTS Dana Point specializes in engineering services to a range of industries in the defense and commercial sectors. More information can be found on the NTS Dana Point webpage, or by calling 949.429.8602.

Solar Radiation Testing in Accordance with Method 505 of MIL-STD-810

MIL-STD-810 Procedure 2 Solar TestingSolar radiation (sunshine) testing is one of the basic tests required for any military equipment planned to be deployed in the open and therefore subject to direct radiation from the solar source. The effects of this radiant energy can generally be divided into two groups or classes, heat effects and photochemical effects. Heat effects on exposed equipment can raise the internal temperatures of the equipment substantially above the ambient air temperature. Temperatures in excess of 160oF have been recorded in parked aircraft exposed to the sun while ambient air temperature was in the 90oF range. Photochemical effects of sunlight may hasten the fading of colors and lead to the deterioration of plastics, paints, rubber and fabrics. The combined effects may lead to the outgassing of plasticizers in some materials along with discoloration and a reduction in transparency.

MIL-STD-810, Method 505.5 outlines two procedures for performing the Solar Radiation test. Procedure I requires a cyclic exposure based on the diurnal cycle and is most useful for determining heating effects on exposed materiel as well as materiel enclosed within a container. Procedure II is a steady state (non-cyclic) exposure most useful for evaluating actinic (photochemical) effects of ultraviolet radiation on materiel since it represents an accelerated test with a factor of 2.5. Because Procedure I is more akin to a natural cycle and does not have the acceleration factor of Procedure II, it is not an efficient cycle with which to evaluate long term exposures. Therefore, when it is used mainly to evaluate the direct heating effect, Procedure I can be performed with source lamp arrays emitting less than the full solar spectrum. Procedure II however, demands full spectrum sources emitting light in the ultraviolet range if the total effects of long term exposure are to be properly evaluated.

The solar light spectrum has been accurately measured over the wavelength range of 280 – 3000 nm as well as the power distribution within this range, and it is this range that we would seek to reproduce in the Solar Radiation test.  Reproducing this entire range using lamp sources however can be quite challenging. Sources emitting ultraviolet wavelengths between 280 and 400 nm tend to be quite costly and their performance deteriorates quickly. Some of the MIL-STD recommended sources such as xenon arc and carbon arc fall into this category.  In fact, it was reported that the first commissioned sunshine test facility in 1945 fell short of the contract requirements due to several deficiencies, one of which was the amount of UV that could be produced at the test item. Cost and reliability issues are why many test labs have chosen to perform only Procedure I  with source lamps covering the visible and infrared spectrum range of 400 – 3000 nm (0.4 – 3.0 µm).

Reproduction of the required environment for the Solar Radiation test requires a chamber space in which the ambient air temperature and airflow over the test item can be controlled as well as a solar light source which may consist of a single source in the case of arc-type lamps or a multiple source array in the case of metal halide or incandescent type lamps. The distance of the light source from the test item may be varied to achieve the required irradiance. Airflow over the test item can significantly impact test results. When MIL-STD-810D introduced the “cycling for heat effects” (Procedure I) the guidance for airflow was to use airflow as low as possible consistent with achieving satisfactory control of the ambient air temperature at the test item or between 0.25 and 1.5 m/s (50 to 300 ft/min). The current guidance from MIL-STD-810G has changed for procedure I to 1.5 to 3.0 m/s (300 to 600 ft/min) in recognition of better field data. The requirement for peak radiation intensity at 1120 W/m2 has changed little over the history of the Solar Radiation test although there have been slight changes to the spectral energy distribution based on updated measurement techniques of the actual solar source.

When the primary concern is testing for heat effects, the question is often asked why an oven or chamber test for enclosed equipment could not be used in place of the Solar Radiation test.  The primary reason is that ovens and chambers transfer heat from a uniform ambient atmosphere surrounding the test item, whereas the solar test transfers heat through direct radiation. The directional effect of radiant heating produces temperature gradients through the test item that are not replicated in ovens or temperature chambers.

When a Solar Radiation test is required,

  • Perform the Solar Radiation test prior to the High Temperature test, as the product temperature measured in the solar chamber may need to be used as the ultimate high operating temperature for the product.
  • Consider the orientation of the test item within the solar chamber so as to replicate the in-use conditions with respect to both the direct radiant light energy and the airflow direction. This will affect both the temperature gradients and any cooling effects provided by the airflow.
  • When testing to Procedure I, remember that several consecutive cycles will likely be required for the product to achieve the ultimate high operating temperature for the most critical area of the test item to be within 2oC of the previous cycle. This usually means 3 to 7 cycles.
  • If operation of the test item is required, operational times will need to coincide with the peak response temperature of the test item in each cycle which will not coincide with the peak radiation intensity.

Scanning Electron Microscopy (SEM) Capability Expansion at NTS

SEM - Close Up of Fracture Surface, 1000X

SEM – Close Up of Fracture Surface, 1000X

NTS Baltimore announces the addition of the new JOEL InTouchScopeTM JSM-6010LA Scanning Electron Microscope (SEM) with fully integrated expanded EDS (energy dispersive X-ray analyzer).

SEM - Overview of BGA Solder Joint, 90X

SEM – Overview of BGA Solder Joint, 90X

This research-grade SEM provides high resolution imaging and a range of acceleration voltages in both high and low vacuum modes.  The embedded JEOL EDS system with silicon drift detector technology now includes spectral mapping, multi-point analysis, automatic drift compensation, partial area, line scan, and mapping filter functions.  Additionally, the JSM-6010A features simultaneous multiple live image abilities that allows the client to view images remotely with magnifications from 5X – 300,000X.

SEM - Overview of Surface Pitting, 400X

SEM – Overview of Surface Pitting, 400X

“This new “live” capability will allow NTS to work more closely with our clients, allowing them real time access to their analysis from the comfort of their office”, stated Keith Sellers, Operations Manager at NTS Baltimore, adding, “From there, the client can provide immediate instruction as to how the analysis can be focused or how the analysis can be changed to meet their specific need”.

Learn more about the SEM/EDS Analytical Services on our main website or contact us today to discuss your next program.