DES, Author at Delserro Engineering Solutions

Accelerated Life Product Reliability Testing of a Carrying Handle

HALT Accelerated Product Life Cycle Testing — Customized ALT Setup by DES

A leading medical technology company contracted DES to perform Product Reliability Testing of a carrying handle. A sample of the test can be seen below and in our video library. The carrying handle had to be pulled, released, rotated and subjected to a sizable lifting force, approximately 20,000 times during its life time.

DES has considerable capability to complete product reliability testing. The main challenge for this project was that each cycle consisted of complex motion. The motion included pulling/releasing the handle to unlatch/latch a pin while rotating the handle. In order to achieve this, DES had to design fixtures and mechanisms that would reposition the carrying handle into each of the designated positions. The number of cycles was automatically counted until failure or 20,000 cycles were completed. During the test, the force to pull the handle was measured at various intervals. The Accelerated Life Testing was completed successfully demonstrating a high reliability.

Please visit our video library to see more examples of DES’s capabilities.

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Random Vibration Testing

Random Vibration Testing is one of the more common types of vibration testing services performed by vibration test labs. A primer containing a technical explanation on random vibration testing can be found in our blog article Sinusoidal and Random Vibration Testing Primer.

Real world vibrations are usually of the random type. Vibrations from automobiles, aircraft, rockets are all random. A random vibration test can be correlated to a service life if the field vibrations are known. Since random vibration contains all frequencies simultaneously, all product resonances will be excited together which could be worse than exciting them individually as in sine testing. Sometimes random vibrations are mixed with sine vibrations in Sine-on-Random Vibration Testing. Also, a low level of broad band random vibration can be mixed with additional high levels of narrow band random vibrations in Random-on-Random Vibration Testing.

Some common test standards that have specifications for Random Vibration Testing are:

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DES Increases Combined Temperature & Vibration Testing Capabilities

DES added another larger AGREE Chamber to perform Combined Temperature and Vibration Testing. This gives DES additional capability to perform combined environmental testing on larger products. DES has performed Combined Temperature and Vibration Testing on car engine sensors, helicopter sensors and outdoor heavy industrial products. Some of the test specifications include MIL-STD-810 and General Motors GMW 3172.

The Equipment Capabilities Are:

Combined shock or sinusoidal, random, mixed mode vibration and temperature
Temperature range from -80°C to +180°C (-112°F to +356°F)
Temperature rate of change up to 20°C/minute
9 cubic feet interior work space, cvo

To learn more about our combined temperature and vibration testing services, visit our website, and be sure to contact us if you would like to find out how our services can work for your products.

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Sinusoidal Vibration Testing

Sinusoidal or Sine Vibration Testing is one of the more common types of vibration testing services performed by vibration test labs. See Sinusoidal Vibration Basics to learn more about vibration fundamentals. A primer containing a more technical explanation on sinusoidal vibration testing can be found in our blog article Sinusoidal and Random Vibration Testing Primer. The types of Sinusoidal Vibration Testing are Sine Sweep Vibration Testing, Sine Dwell Vibration Testing, and Sine-on-Random Vibration Testing.

Continue reading Sinusoidal Vibration Testing →

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Accelerated Life Cycle Testing of a Case Handle

A leading commercial product manufacturer contracted DES to perform Accelerated Life Cycle Testing of a case handle. A sample of the test can be seen below and in our video library. The handle had to be opened and closed many thousands of times during its life time. In addition, two thirds of the cycles had to be completed with the sample exposed to hot and cold temperatures.

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Three Axis Vibration Testing

Most vibration test specifications require vibration testing along 3 orthogonal axes. Vibration testing using most ElectroDynamic (ED) Shakers is performed 1 axis at a time. However the orientation of the ED shaker or the Device Under Test (DUT) can be changed to complete testing along all 3 orthogonal axes.

Many ED shakers can be rotated and connected to a horizontal table called a slip table,

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Constant Temperature Accelerated Life Testing using the Arrhenius Relationship

When products are mainly exposed to temperature stresses in the field, Constant Temperature Accelerated Life Testing is used to simulate product life. Products can be tested at temperatures above their normal use temperature during Constant Temperature Accelerated Life Testing in order to accelerate aging. Defects or failure modes that would show up after many years in the field at normal use temperatures can be detected in short times in an Accelerated Life Test. In Constant Temperature Accelerated Life Testing, the typical failure mode is dependent on migration/diffusion or chemical reactions. These types of failures are typically found in electronic components but can also occur in other types of products or materials such as adhesives, batteries, etc. The Arrhenius Equation relates reaction rates to temperature and is used to correlate time in the field at normal use temperature to a Constant Temperature Accelerated Life Test. It should be noted that constant temperature testing will not precipitate failure modes due to thermal cycling. Temperature or thermal cycle testing will be discussed in another blog article.

The Arrhenius Equation that relates reaction rates to temperature is:

Continue reading Constant Temperature Accelerated Life Testing using the Arrhenius Relationship →

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Product Life Cycle Testing of a Drawer Used in a Medical Product

This is a case study of a reliability test performed by Delserro Engineering Solutions, Inc. (DES) on a drawer used in a medical product. A sample of the test can be seen in our video library. DES was contacted by a leading medical equipment manufacturer to perform life cycle testing on a new product. One of the major components to be reliability tested was a drawer. This drawer had to be open and closed many thousand times during its lifetime.

First, DES developed a reliability test plan that defined how the tests would be performed, the number of samples required and how the test results would be quantified into a field life. After the plan was approved by the manufacturer, the reliability test had to be designed.

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Classical Shock Testing

Classical shock testing consists of the following shock impulses: half sine, haversine, sawtooth, and trapezoid. Pyroshock and ballistic shock tests are specialized and are not considered classical shocks. Classical shocks can be performed on Electro Dynamic (ED) Shakers, Free Fall Drop Tower or Pneumatic Shock Machines. The parameters required to define a shock test are peak acceleration expressed in G’s or m/sec^2, shape of the impulse, and duration in milliseconds. A classical shock impulse is created when the shock table changes direction abruptly. This abrupt change in direction causes a rapid velocity change which creates the shock or acceleration impulse.

Classical shocks are applied along one direction and one axis at a time. Most specifications require the product to be shocked in both the positive and negative directions along each axis. If shock tests are performed on an ED shaker, the shaker can reverse polarity and perform the shock along both directions of each axis without rotating the fixture and specimen. When performing shock testing on a shock machine, the machine can only apply shock in one axis and one direction. The fixture and specimen must be rotated to apply shocks along different directions and axes.

A typical shock test setup using a pneumatic shock machine is shown in Figure 1. DES can also perform shock testing using an ED shaker and drop tower.

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Recent Testing Projects

We had many interesting test projects at Delserro Engineering Solutions this past month:

We completed a Pyroshock test on our Mechanical Impact Pyroshock Simulator (MIPS) on equipment that will fly into outer space.
On the other end of the altitude spectrum, we completed environmental testing of components that will be used in submarines to MIL-E-917. MIL-E-917 is a military specification for Naval shipboard electric power equipment.
In the middle of the altitude range, we performed combined temperature and vibration testing on sensors that will be used in automobile engines to specification GMW 3172. GMW 3172 is a General Motors Specification for electronic component durability.

The following is a sample of some additional testing projects we have completed recently:

Continue reading Recent Testing Projects →

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