MGA Space Series, Part 2: Extreme Pyroshock Simulation

For the past two decades, MGA has supported testing in the aerospace industry with our pyrotechnic shock simulations, providing an extensive history of performing tests under the most extreme scenarios. MGA is no stranger to pushing the boundaries of what our systems are capable of, including achieving high acceleration magnitude Shock Response Spectrum (SRS) profiles, testing uniquely shaped and/or large mass Units Under Test (UUTs), and even accommodating complex SRS profiles comprised of multiple knee frequencies. These scenarios pose an intriguing challenge; what can we do to address them?

In this second installment of MGA’s Space Series, we will explore the technical ins and outs of how our pyroshock systems can overcome the most demanding test conditions centered around our most frequently asked questions:

Scenario 1: How can I achieve severely high acceleration levels?

Technical Overview 

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Within the space industry, a common method for creating high-acceleration environments is by using actual pyrotechnics. However, the main drawback for the ordinance- style of testing is that it can be very destructive, subjecting UUTs to forces beyond what they would normally see in just a shock-simulated test. MGA’s pyroshock systems can create these high accelerations without the use of explosives.

Fundamentally, MGA’s pyroshock system generates the shock pulse by firing a puck directly into the resonant beam upon which the UUT is attached. The primary factor to consider is the amount of energy introduced to initiate the shock. When achieving higher accelerations, more energy is required within the system. Based on the principles of kinetic energy, mass, velocity, or both variables need to be increased to deliver a more severe shock. MGA offers multiple puck sizes with varying masses, ranging from 2 to 100 pounds, specifically chosen based on the SRS profile for the given test. To generate more velocity with this puck, the pressure at which the puck is fired into the resonant beam can also be increased.

Another variable that plays a role in the magnitude of the acceleration response is the amount of deflection the resonant beam experiences. Typically, higher deflection in the beam will result in lower accelerations for the high-frequency domain. Conversely, lower deflection will result in higher high-frequency domain accelerations. MGA currently has two beam thicknesses available: 1” thick and 2” thick.[AP3]  The thicker beam provides higher stiffness, thus minimizing deflection and allowing for extraordinary acceleration levels.

Case Study – High Acceleration

By combining each of the methods described above, MGA’s pyroshock systems can achieve acceleration levels exceeding 20,000 G’s. As an example, to accomplish the profile below, which has a maximum acceleration level of 22,000 G’s, a 100-pound puck was fired at 600 psi into the 2” thick resonant beam.

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Scenario 2: Will I still be able to test my UUT if it is large or uniquely shaped?

Technical Overview

As the complexity of space industry components continues to increase, the demand for testing larger systems has also risen. Whether it be larger individual parts, or complete sub-systems, we can perform tests for a wide range of UUT shapes, sizes, and masses.

MGA’s solution for testing large UUTs is our Large Mass Pyroshock System. Capable of payloads up to 500 pounds, this equipment is ready for a broad range of test articles. The resonant beam features two options for width, 12” and 24”, creating a spacious area for mounting test fixtures.

Much like the high acceleration scenario, more energy is needed within the system to generate the desired response. As a result, the same techniques are often deployed as the mass of the UUT grows: increase in puck mass and increase in pressure.

Another one of our solutions is to use multiple outputs from our pyroshock controller. By introducing a second, and sometimes even a third impact puck, we can increase the overall energy output. All these options ensure that the right amount of force is applied to the UUT.

Case Study – Large UUT

MGA has historically performed testing for some exceptional UUTs. In some cases, the total mass of the fixture and test article has exceeded 500 pounds. The setup shown below utilizes a 24” wide resonant beam, common for larger UUTs. However, even if the article cannot fit on the beam, it does not mean that testing is impossible – MGA can and has tested articles over 6-feet tall! This setup also features three of our medium-sized cannons, a critical feature for this situation.

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Scenario 3: What if I have an SRS Profile with multiple segments?

Technical Overview

Even though some shock response profiles only incorporate two or three segments, we frequently see SRS levels with four, five, or more sections. This may be a result of the profile being generated from a combination of simulated profiles, or perhaps multiple knee frequencies exist for the test domain. Whichever the case, MGA’s large and mobile pyroshock systems’ plentitude of variables let the user tune all aspects of the SRS profile.

A highlight of MGA’s Pyroshock System is that it utilizes a tunable resonant beam approach, increasing its effectiveness compared to a standard Mechanical Impact Pyroshock Simulation (MIPS) Table. The main feature that makes our system ‘tunable’ is the adjustable beam clamps. By moving the clamps closer or farther away from the UUT, the knee frequency is shifted, thus affecting the slope of the low-to-mid-frequency SRS profile.

Furthermore, adjusting the torque of the fasteners on these clamps can help induce or magnify various modal responses once the beam is impacted, resulting in significant changes to the low-frequency domain.

On the opposite end of the Shock Response Spectrum, the high-frequency domain can also be tuned by utilizing a damping material placed between the resonant beam and the impacting puck. Damping plays a critical role when the initial response of the impact needs to be adjusted without making any changes to the remainder of the shock response.

Case Study – Complex SRS Profile

The ability to fine-tune multiple variables makes it possible to simulate unique and irregular shock conditions that others might shy away from. In the example below, the SRS profile is made up of six segments, thus affecting the slope of the nominal curve across multiple frequencies. To achieve this profile, the beam clamps were torqued as tight as possible to decrease the low frequency accelerations, and the clamp distance was maximized to create a steep and uniform slope matching the steps in the SRS profile. For this case, minimal damping material was placed on the underside of the beam, allowing for a natural, downward sloping, acceleration decay in the high-end frequencies.

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The MGA Advantage

MGA’s commitment to developing cutting-edge pyroshock simulation solutions allows us to tackle the toughest, most difficult testing scenarios. Whether it's an oversized UUT, a tricky SRS profile, or extreme acceleration levels, we continue to refine our pyroshock systems to ensure that nothing is impossible.

In the world of aerospace testing, where every fraction of a second and every bit of force counts, MGA is proud to lead the way in advanced simulation technology. We don’t just adapt to the impossible, we make it possible.

MGA Space Series – What’s Next?

Stay tuned for the next parts of our series, where we’ll explore:

➡ TVAC Testing: Ensuring spacecraft endure the extreme conditions of space.

We are devoted to significantly investing in the future of space exploration, all while offering our clients the most advanced testing solutions available today, tomorrow, and beyond. If you are interested in learning more about our space capabilities, fill out our contact form today!

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