At NTNU we help surgeons and offshore drillers at the same time. How?
When you have a corrosive environment like in the ocean or right inside your body and you want to have a component working under cyclic loading and wear, component design and material selection can be very challenging. All the components and parts that are performing in these conditions are very costly and used for critical operations. Imagine a hip implant with certain life span should be changed after a period of time, or piston rod which is 20 meters long and used in offshore drilling. For instance, if a piston rod fails and causes loss of tension in the drilling riser, it will cost more than 3.8 Million kroner per day to stop operation and fix the problem.
The challenge is far more complicated than assumed; there is not simply an add up of wear, corrosion and fatigue, there is corrosion-wear, fatigue-wear, corrosion-fatigue and also corrosion-fatigue-wear that should be added to the equation. All these degradation mechanisms have effects on each other as well as acting solely on its own. That is why we call it multi-degradation.
Why do the components fail?
The first approach to solving this problem is to find a way to simulate the real condition in the lab, and that is when lab scale multi-degradation (LSMD) test rig comes in; a unique, patented, in-housed designed and built test rig by NTNU and National Oilwell Varco. LSMD test rig simulates wear, corrosion and cyclic bending (fatigue) at the same time and measures potential and stress.
LSMD test rig can shed light on why, when and how these components fails, therefore it is possible to replace them before putting lives in danger or breaks other parts and systems working in parallel with them. On the other hand it gives industry a chance to develop and test new materials; imagine you can make a drilling and operating system that have a life time more than an oil reservoir, it is installed once and does not need any maintenance. Or an implant which has a life time more than 100 years, a patient can receive the implant and does not need to go under surgery again.
The understanding of multi-degradation phenomena is very little, at the moment our research group is more focusing on the basic science behind the phenomena, once mechanisms are found, the path is open for further recommendations to inhibit degradation. After each test, samples are fully investigated by means of electron, X-ray photoelectron and focused ion beam microscopy, these characterization techniques enables us to study structures, chemistry, and different aspects of surface and subsurface.
This technology helps us produce more reliable and longer lasting components and parts. It helps us save lives, reduce costs and simply make the world a better place to live.
Photos: NTNU/Marit Solheim
This blog post was written by PhD Candidate Amin Hossein Zavieh at NTNU – The Department of Engineering Design and Materials.