Case Study: Sub-Miniature Samples

The Challenge

Reverse engineering an existing part requires knowing the material properties as well as the physical dimensions. For example, a replacement drive shaft on your car may look identical to the original, but if it were made of glass and not steel your traveling days would be short-lived.

One of the customers of Innovative Test Solutions, Inc. (ITS) needed to verify that the material properties of a replacement part were identical to the original.

The challenge was the size of the part as it did not allow us to extract standard specimen sizes typically used to run cyclic fatigue, tensile, and stress-rupture testing.

We had to scale down the specimens to fit the material provided and adapt the machine fixturing of the sub-scale specimen by creating a custom creep and rupture frame.

The Solution

Using ratios for a standard sized specimen, we scaled down the part to a point where it was the thickness and length of a quarter. This allowed us to extract a specimen from within the material boundaries of the parts and provide the customer with a sample size that would allow for material properties testing.

In tandem we had to design a grip system that would attach to the sub-scale fatigue and tensile bars. We also needed to prevent bending while installing it into a standard servo-hydraulic fatigue frame.

For the stress-rupture specimens, we used the same sub-scale geometry and re-designed the fixturing and strain measurement instrumentation to accommodate the small sample sizes. Off the shelf stress-rupture frames utilize a multiplying arm ratio to reduce the amount of dead weight required to achieve the required static stresses.

Due to the sub-scale size of the samples, we had to design and fabricate a stress-rupture frame that did not require the multiplying effect while still providing a static load, alignment that would not induce abending under load. Additionally, we had to be able to acquire the digital data recording of the temperature, creep strain, and static load applied.

The Results

ITS, along with our sister company, Innovative Machining Services (IMS), now provides our customers with the ability to extract, machine, and test these sub-sized samples for a variety of testing needs.

Our Sub-Miniature Creep and Stress-Rupture Frames and hardware can endure temperatures of up to 2000°F.

The same can also be said for our Sub-Miniature Tensile and Cyclic Fatigue Testing. Through this service, we can cover sub-ambient temperatures of up to 2000°F while providing closed loop, strain-controlled testing with digital data acquisition.