Package Testing

Package testing subject packaged items to the handling stresses encountered during transportation and storage. The tests consist of drop tests, storage tests such as stacking and compression. Temperature, tests and transport vibration simulation.

Below is a video of what the transport vibration simulation actually looks like.

Structural Failure Seminar

Aero Nav Laboratories, Inc. will be giving a seminar on the failure of engineering structures. The presentation will be given by the Vice President of Marketing and Business Development at Aero Nav Labs, Sheldon Levine.

Sheldon Levine has a Bachelors and Master’s degree in Mechanical Engineering from the City College of New York.

The seminar will be held at 4 Irving Place in Manhattan, NY on behalf of the American Society of Mechanical Engineers (ASME) on Thursday, November 17, 2011 at 5:30 pm.

For any questions regarding the seminar please contact Aero Nav Laboratories, Inc at 718 939 4422 and ask for Sheldon Levine.

Noise Testing

Noise testing of equipment is performed with two distinct objectives:

1. To verify the ability of the equipment to withstand its external acoustic environment without unacceptable reduction in its functionality and/or structural integrity. Equipment may be subjected, for example, to a severe externally generated noise environment when the unit is located, for instance, on aerospace vehicles, or in power plants.

2. To measure the noise generated by the equipment and radiated into the equipment. Self-generated equipment noise is of two types:

• Airborne noise is that which is produced by a source that radiates directly into the air. The airborne sound waves are transmitted by pressure fluctuations in the air.

• Structureborne noise occurs when items are set into vibratory motion by equipment noise sources. The vibrational energy is consequently transmitted throughout the structure where it will force various surfaces to vibrate. The vibrating surfaces in turn transmit their motion to the air causing pressure fluctuations that are then propagated as airborne noise.

Another, perhaps simpler definition, is where noise travels over at least part of its transmission path by a means of vibration of a solid structure. Structureborne noise is determined in the chamber, with the unit under test isolated from the floor, by measuring the equipment vibration levels.

Test Equipment

Externally generated noise testing

Externally generated noise testing is usually, but not always, performed in a reverberation (with echoes) chamber. External noise testing is usually quite severe and is not as affected by background noise or echoing, as may be the case with self-generated noise testing. The reverberation chamber provides a diffuse field where the noise is reflected many times.

Self-generated noise testing

Self generated noise testing is usually, but not always, performed in an anechoic (without echoes) chamber that serves to eliminated interference from intruding background noises such as environmental, support equipment, transportation sources, etc. it also eliminated reverberations within the chamber. Where the external noise interference levels are of a low value, testing inside a chamber may not be necessary.

The chamber is typically constructed of modular steel sheeting with interior surfaces of wedge shaped panels that dissipate acoustic energy by vibration of the material.

Noise test procedures

Test procedures for noise testing are provided in MIL-STD-740, MIL-STD-810 and others.

Test conclusions

Once the acoustic characteristics of the equipment are determined during testing, steps can be taken to modify designs, materials, etc., as needed to achieve the required self-generated noise levels. With externally generated noise, steps can be taken to reduce the equipment susceptibility to the noise environments.

Where the equipment under test is part of a larger system or assembly, various abatement techniques can be undertaken as necessary to achieve the required overall acoustic levels.

Special techniques are available to achieve the desired acoustic levels by addressing the following:
• Reduction of noise generated by the source (source treatment;
• Controlling noise along the transmission path (path treatment);
• Reducing noise at the receiver (receiver treatment).

Noise abatement measures are well presented in the engineering literature and are effective when properly applied.

Enclosure

An enclosure is a mechanical item which either partly or wholly surrounds a component or assembly. The enclosures are designed to provide varying degrees of environmental protection as listed below:

• Airtight
• Dusttight
• Splashproof
• Submersible
• Explosionproof
• DirtProof
• Dustproof
• Spraytight
• Wateritght
• Hermetic

The Laboratory is equipped to perform testing to verify the customer selected degree of protection.

Vibration Testing

Vibration testing is performed to demonstrate the ability of equipment to withstand the expected dynamic vibrational stresses encountered in service.

Basic Vibration Modes

• Sinusoidal - Vibration characterized by amplitudes which vary sinusoidally with time.
• Random - Vibration characterized by irregular non-repeating patterns and amplitude versus time. Random vibration more closely simulates the real world.

Mixed Vibration modes

• Sine on random - sine and random vibration are produces simultaneously to simulate the sources where both sinusoidal and random vibration are generated in service
• Random on random - Two different random vibration patterns are produces simultaneously to simulate sources where two separate random inputs are generate din service.

Mixed vibration mode attempts to more closely simulate the real world environment than either sine or random separately.

Gunfire

Test pulses are also available which simulate the vibration caused by overpressure pulses produces in the vicinity of armaments.

Sheldon Levine
Vice President of Marketing and Business Development
Aero Nav Laboratories, Inc
14-29 112 Street
College Point, NY 11356

Shock Testing

Shock testing in the laboratory can take two approaches. Simulation of either the specified shock conditions or the response of the system, known as a shock response spectrum (SRS), can be performed.

Specified Shock Testing

The most common type of specified input simulation is known as classical shock testing. It consists of inputting various relatively non-complex waveforms. The three most common are shown below:

Common Shock Pulses

(A) RECTANGULAR PULSE

The amplitude is constant over the time-frame

Meaning the acceleration remains unchanged

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(B)SAWTOOTH PULSE

The amplitude peaks at the end of the time-frame

Therefore the acceleration increases linearly

|

(C) HALF- SINE PULSE

The amplitude varies sinusoidally over the time-frame

The acceleration increases periodically in the shape of a sine curve

|

These shock pulses are idealized versions of the most common pulses that are encountered in service. Equipment is available in the laboratory to simulate the different pulses shown above. The selected test pulse is dependent upon the actual service environment.

Shock Response Spectrum

When testing is required to produce a laboratory shock pulse having a spectrum tailored to that of the actual environment, shock response spectrum simulation is performed. A typical shock response spectrum, as shown is a plot of acceleration versus frequency.

Extracted from:
TEST Engineering & Management

Article by:
Sheldon Levine
VP Marketing & Business Development
Aero Nav Laboratories, Inc.
College Point, NY

To exemplify how shock testing is performed at Aero Nav Laboratories here is a video

Acceleration Testing

How do companies test equipment based on how well they perform under acceleration? Well through acceleration testing of course. A better question is how do test labs perform acceleration tests.

These tests are performed on equipment that experience changes in speed and direction of their movement. Such equipment could be on aircraft such as aerospace vehicles and airplanes, missiles, trucks, etc. It is important for equipment that are on such vehicles to perform well under acceleration loads, otherwise mere travel could hinder the performance of such equipment.

Test labs utilize a centrifuge (shown below) to generate the acceleration loads, also called inertial loads, by the rotation of the test item about a fixed axis. The induced load is constant for a specific rotational speed. The direction of the acceleration load is radially outward from the axis of rotation. Meaning that if a suitcase for example is placed on the centrifuge shown below, the force is away from the center of the centrifuge.

The magnitude of the load is directly proportional to the distance from the center of the centrifuge, and proportional to the square of the rotational speed. Therefore if the rotational speed is tripled, the force is increased by a factor of 9.

Testing is typically performed at constant speed. This is required to ensure that the test item has sufficient time to fully distribute the resulting inertial loads and that the resonant (or dynamic) response is not excited. However, the speed can be varied at moderate rates of change.

Acceleration causes loads on all components of the test item, including liquids. MIL-STD-810 provides a partial listing of detrimental effects that may occur from high levels of acceleration, Acceleration loads testing should be performed if any of the following effects are critical to the integrity and functionality of the equipment:

• Structural deflections that interfere with material operation
• Permanent deformation and fractures that disable or destroy material
• Broken mounting hardware such as fasteners and supports that seals that leak
• Pressure and flow regulators that change value
• Pumps that cavitate
• Spools in servo valves that are displaced causing erratic and dangerous control system response.

Aero Nav Laboratories’ centrifuge is equipped with a 48-channel slip ring assembly for control and instrumentation circuitry as well as pneumatic and hydraulic supply slip ring assemblies, for use when required. There is also a capability for the installation of a video recorder.

The rotating portion of the centrifuge consists of two arms that are capable of carrying a maximum weight of 500 pounds. Maximum rotational speed is 185 rpm. The centrifuge can generate acceleration levels up to 80 G’s. To put things in perspective, if a 150 pound person experienced an acceleration load of 80G’s, they would feel like they weigh 12,000 pounds.

Extracted from:
TEST Engineering & Management

Article by:
Sheldon Levine
VP Marketing & Business Development
Aero Nav Laboratories, Inc.
College Point, NY

Environmental test lab restructures its business model

Here at Aero Nav Laboratories, we have been observing for many years the changes in the way that companies conduct their businesses, as well as the vicissitudes of the marketplace. Consequently, Aero Nav has decided to modify its business model, broadening its scope in this changing and volatile economy by realigning it more closely to the conditions and priorities of the current business scene.

A “business model,” commonly used in today’s commercial environment, is a framework for describing the varous aspects of a business including its purpose, its infrastructure, its practices and operational processes, its policies. In summary, it is seen to provide a guide for the current and future conduct of a company in its unique business environment.

Aero Nav is an environmental testing laboratory that has served the military and industrial communities for many years, The lab includes among its customers most of the major companies in the defense sector and many companies in the non-defense sector. The laboratory’s busines model was based on serving this specialized field.

During those years, the laboratory has accumulated a significant database of capability and experience derived from the exacting requirements of our customers. The lab has consequenlty built up a knowledge resource in related fields such as inspection and test witnessing, prototype fabrication, functional and developmental testing, engineering services, component and equipment assembly, etc.  This related capability and experience is a natural derivative of the laboratory’s environmental testing services.

Consequently Aero Nav has expanded its business model to include what is called contract work services-defined as the performing of tasks on an individual contracted basis-and will include any of the items previously noted.  These services may prove to be cost-effective when customers need to outsource all or a portion of their production and program efforts.

The advantages of contract work services for customers include:

• Reduced engineering and manufacturing in-house costs.
• Reduced in-house work load.
• Single point of contract for multiple services.
• Ability of the lab to customize its contract services to suit the customer’s unique requirements.
• A source of required services which are outside the core competence of the customer

The restructuring of the laboratory’s business model to include contract work services will serve to provide a broader base for operations in an uncertain yet promising business climate.

Extracted from:
TEST Engineering & Management, October/November 2008

Article by:
Sheldon Levine
VP Marketing & Business Development
Aero Nav Laboratories, Inc.
College Point, NY

Reliability Through Testing

Openness

As an environmental simulation company, we feel that it is important that we provide openness in regards to what happens in our laboratory. Giving our customers and other individuals a convenient way of showing how our tests are performed is important to build trust.

We hope that our blog will provide more awareness of the environmental simulation testing field among both technical and non-technical individuals.

Our sites
www.aeronavlabs.com
www.contractworksolutions.com