Predicting Fatigue In 3D Printed Medical Devices

Medical devices are getting smarter and more customized. But one stubborn problem remains: predicting fatigue in metal implants that have to perform reliably inside the body. Additive manufacturing (AM) has made that problem even trickier. Yes, 3D printing enables patient-specific devices — titanium hips shaped to the individual, spinal rods tailored from advanced alloys — but it is unknown exactly how long these parts will last.

The challenge comes down to variability. Microscopic grain structures, the way those grains line up, and tiny defects introduced during printing — pores, cracks, voids — all affect durability. For device makers, that variability isn’t just an engineering headache. It’s a regulatory one too, especially for implants expected to function for decades.

The Fatigue Problem in Additive Manufacturing

Traditional medical devices manufactured through casting or machining have long-established performance data and validated lifespans. In contrast, AM medical devices present quite a bit more uncertainty. Their performance is less predictable, and their failure mechanisms can differ significantly from conventionally produced parts.

For manufacturers, this uncertainty translates into higher testing costs, longer development timelines, and greater regulatory scrutiny. Fatigue — the slow breakdown of a material during repeated loading cycles — is especially tricky to predict because it often comes down to rare, hard-to-spot weak points that cause failure much earlier than expected.

Other properties, like strength, can be characterized with one or a few tests, as they are measured as the average behavior of a material. However, fatigue failure occurs due to the weakest link at the microscale. Manufacturers must design around that point of failure, rather than the average, to make sure the part doesn’t fail unexpectedly.

Device designers and quality analysis and control engineers are seeking new tools that can help them with that work, especially in AM parts that will be subjected to physiological loading.

ICME’s Role in Solving Fatigue Challenges

Integrated Computational Materials Engineering (ICME) offers a powerful response to this challenge. By combining physics-based modeling, materials science, and component-level analysis – what we call “materials concurrency” – ICME enables manufacturers to simulate how materials and the medical devices that contain those materials will behave under real-world operating conditions. This approach makes it possible to model fatigue life virtually, long before a part is printed or implanted.

Recent advances in ICME software support precisely this kind of predictive engineering. These tools allow manufacturers to simulate how factors such as material composition, microstructure, and loading conditions interact to affect fatigue performance. For medical device developers, the implications are profound: they can make informed design decisions earlier in the development cycle, reduce their reliance on trial-and-error testing, and generate more robust data for regulatory submissions.

ICME also plays a key role in managing the unique challenges of AM. Because AM introduces more variability than traditional methods, it also increases the uncertainty in how a part will perform. ICME tools can help reduce that uncertainty by identifying the most likely failure modes and predicting the number of loading cycles a part can endure before fatigue failure occurs.

Case Study Insights

This is not a theoretical proposition. ICME is already reshaping the way medical device companies approach design, from reducing physical testing in additive workflows to accelerating material innovation in high-stakes clinical applications.

In a program involving heart stents, we collaborated with a manufacturer to develop a shape memory alloy for improved radiopacity, which is critical for ensuring the device remains visible under X-ray imaging. This visibility enables minimally invasive surgeries where heart implants can be inserted through a vascular catheter with a small incision reducing patient risk and improving recovery time.

Each heart beat is a loading cycle, so these devices are subjected to hundreds of millions of loading cycles over the course of a decade. The goal was to maintain fatigue performance while enhancing visibility. With these improved properties, stents can be made thinner and still be visible. By reducing the thickness of the device, this advancement reduces the amount of foreign material introduced into the heart while enabling robust fluid flow through arteries.

These devices are usually made of extraordinarily expensive materials, such as palladium and platinum, in order to achieve the properties necessary for minimally invasive surgery. However, by leveraging ICME, we were able to replace these critical elements with hafnium, reducing cost by around 90 percent. Further, using AM, these devices can be printed to net-shape, meaning there is no wasted material through machining, limiting the cost per device.

Here, ICME tools helped identify the right compositional and processing adjustments without requiring years of trial-and-error prototyping. What is otherwise a niche high-end procedure can now be made more accessible to the masses.

Future Outlook

The move toward bespoke medicine and custom-fitted medical devices will continue to drive demand for predictive modeling tools. While additive manufacturing opens new design possibilities, it also increases the need for lifecycle assurance. With ICME tools, developers are better equipped to evaluate how a part will perform over time, an especially valuable capability in a regulatory environment where evidence of safety and durability is paramount.

Beyond reducing failure rates, these tools could also have a significant impact on patient outcomes. Devices that are tailored to a patient’s anatomy and performance requirements, and that can be trusted to last, offer the promise of faster recoveries, fewer revision surgeries, and improved long-term health.

The medical device industry has always balanced innovation with caution. As ICME becomes more integrated into design workflows, it offers a pathway to innovate faster without sacrificing reliability. That is a step forward for patients.