Testing the Physics of Failure With Accelerated Life Tests

In the real world, a product is subjected to massive variation in temperature, pressure, and humidity. Highly accelerated life testing and stress screening helps researchers and product engineers gather important reliability information about component life, and determine the specific characteristics of a product that could cause the product to fail prematurely.

An autoclave can be an ideal tool for accelerated life cycle testing. But good accelerated life cycle testing demands equipment with precise and accurate temperature and pressure controls, customisable pressure and temperature ramps, detailed logging, automatic cycle repeat, and a flexible programmable control system. Not every autoclave gives you that level of precision and control. A Priorclave does.

Stress-Testing With Autoclaves to Improve Reliability Engineering

Accelerated life tests have different names in different industries. Consumer goods and construction materials are subjected to “accelerated durability studies” (sometimes called “destructive testing”). Canned foods and shelf-stable foods undergo “accelerated shelf life testing.” Pharmaceutical companies put products (both drugs and their packaging) through mandated “stability testing.” A wide range of industries rely on “highly accelerated stress screening” (HASS) for their electronic components.

Whatever you call it, it all boils down to using specific parameters for heat and humidity to approximate a highly accelerated life cycle, controlling the stress level parameters, and determining the stress tolerance of products’ components or systems under normal use conditions.

In many cases, an off-the-shelf environmental chamber is sufficient to simulate high stress conditions to evaluate expected life and time to failure. Even some critical applications can be handled by something only marginally more complex than a home oven. In these cases, if you can verifiably maintain a single stress variable (e.g., holding a steady 60ºC for a specific test duration), then you can produce a reasonable reliability test for years spent sitting on a shelf under normal conditions.

But there are some applied stress tests that require more control over stress level variables to determine products’ reliability and durability during its expected service life. This is especially true when testing advanced synthetic materials, electronic components, or medical devices/package integrity under ASTM standards (such as ASTM F1980).

The Fundamentals of Accelerated Life Testing

Many material degradation mechanisms come down to chemical reactions. And, in most cases, chemical reaction rates approximately double with each increase of 10ºC. For monolithic synthetic materials—such as closed-cell foams, plastics, and polymers—it’s easy to reliably double their ageing rate. On the other hand, for many natural materials (like paper), a 10ºC increase can make ageing occur hundreds of times faster, especially as you begin to vary humidity, UV exposure, and other factors.

Steam-fed industrial sterilisers have been a regular part of the industrial accelerated ageing for decades. But today’s autoclave market is dominated by purpose-built steam-jacketed “medical grade” autoclaves and industrial autoclaves for material processing. These are optimised for a specific task—like curing composites or sterilising instruments to be used during medical procedures. As such, they lack the flexibility, ease of use, and robustness of a “general purpose” research autoclave.

A general-purpose lab autoclave offers significant energy and cost savings, in addition to having a much broader operational range, making it easier to perform more accelerated testing and gather more data. The Tactrol control system included in every Priorclave autoclave can easily run cycles of not just 0 to 120 minutes (i.e., standard medical cycles), or 0 to 999 minutes, but 0 to 999 hours—with “Automatic Cycle Repeat,” if needed. As such, test samples can be subjected to hundreds of identical temperature and pressure ramps without human intervention or “babysitting.” A military contractor can put a sample of their newest ballistic material in a Priorclave, push a single button, and walk away. Their Priorclave will run for weeks on end, simulating years of exposure to harsh conditions.

Determining the Physics of Failure With Quantitative Testing: Priorclave Accelerated Life Tests in the Field

Priorclaves are regularly used to determine the durability of disposable contact lens packaging and lifespan of reusable connectors on electronic medical devices. They’ve tested the limits of the lead-free solder connections in mobile phones and simulated the weathering endured by spacecraft thermal tiles. For years, the U.S. Army has had a Priorclave at their Aberdeen Proving Ground, where it is used for accelerated ageing and destructive testing of ballistic materials.

In 2015 Blue Belt Technologies was working on a new robotics-assisted suite of tools to improve partial and total knee replacement surgery. The system relied on several reusable components that must be sterilised after each procedure. These included an electrical sensor encased in a metal and plastic enclosure assembled with epoxy. Blue Belt had a variety of concerns about how this device would hold up to repeated uses and sterilisation. They wanted to run it through hundreds of sterilisation cycles, but off-site services were expensive, and conventional autoclaves needed to be manually operated and monitored. Under these conditions, even a single testing cycle took months. With our help, Blue Belt increased prototype testing throughput by 500 per cent, performing months of testing in mere days while actively monitoring the tool for drops in voltage or other indicators of failing electronics.

Acceleration Models to Estimate Reliability in the Food and Beverage Industry

Priorclave regularly works with food and beverage manufacturers to test methods for improving mean life within production and packaging. Their programmable research and development autoclaves perform double and triple duty throughout the facility. The QA/QC departments use it for standard lab tasks, like glassware sterilisation and to process waste loads prior to disposal. The research department uses the autoclave to explore potential food production and packaging approaches. Later, that same autoclave can also be used for accelerated ageing and shelf-life testing, as it simulates the effects of high temperature and time on packaging, with multiple heating and cooling cycles.

Improve Reliability Engineering and Identify Failure Mechanisms With Accelerated Lifetime Testing—Powered by Priorclave

Priorclave builds efficient, reliable autoclaves specifically developed for the demands of academic research, R&D, and high-quality accelerated life testing. We prioritise customer service and support: Every Priorclave steriliser is covered by free lifetime remote technical support and consultation and one of the best warranty programmes in the industry. Priorclave also maintains a global network of factory-certified authorised service agents.

When you are ready to discuss your equipment needs, we are as close as a call or click.