Corrosion as the “Good Guy”

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Permanent Bio-Implantable Plates and Screws (Image courtesy of Praisaeng at FreeDigitalPhotos.net)

While plenty of industries abhor corrosion and its consequences, another sector has welcomed it as a step in the healing process: medical devices. Devices have evolved over the decades to be less-intrusive during (and after) implantation. The bio-inert nature of titanium (along with its weight and strength characteristics) has made it the go-to material for structural orthopedic implants (hip and knee joints, bone plates and screws, etc.). These implants are made to go into the patient’s body and remain there, hopefully performing well for an extended period of time without the need for replacement. But what about implantable devices that have a finite life of medical functionality, and afterwards can become detrimental to the patient’s quality of life?

Such is the case with attaching soft tissues to bone during ACL repairs, as described in a recent issue of Advanced Materials & Processes. Stainless steel or plastic attachments have been the accepted materials in the past because of their strength and biocompatibility behaviors. However, once these devices have done their job they can be hard to remove, or can (in the case of stainless steel) cause metal sensitivity in the patient. Implanted screws made of polymer-based biocomposites have been shown to degrade at a safe rate in living bone and tissue. This allows the repaired ligament to heal, while the tool itself is slowly absorbed by the body using its own metabolic conversion system (the Krebs cycle).

Another example is the performing of a balloon angioplasty to unblock clotted arteries. The device employed in this procedure is a balloon-tipped catheter, which widens the artery. A metallic mesh stent is placed in the area where the work was performed, to keep the artery open as it heals from the procedure. The mesh stent never goes away, which can have an unintended outcome as time progresses. In an ideal world, the stent would remain properly positioned in the artery and cause no further damage. In reality, the stent has the opportunity to create major issues in the body after the artery’s healing time (localized inflammation, or structural breakdown resulting in stent fracture and arterial wall damage). A research group at Michigan Tech is looking to take the bio-corrodible nature of zinc and use it to their advantage in stent design. An alloyed zinc stent would perform the necessary function of propping the blood vessel open as it heals, and then would break down into products that are harmless to the body after its function is complete. The degradation rate for zinc in the body has been shown to be approximately 0.015 millimeters/month for the first three months (the crucial timeframe for stent functionality), with an accelerated rate after that.

VEXTEC’s past success with modeling corrosion-induced damage propagation (previously used for corrosion mitigation purposes) provides an exciting opportunity to repurpose this methodology to model the corrosion state in materials and devices in which degradation is in fact encouraged. Whether seen as detrimental or beneficial, the processes of corrosion and fatigue are interrelated. The key to merging the two phenomena lies in reducing the size of the initial flaw (as described by traditional damage tolerance analysis) to better reflect the size ranges that are observed in corroded surfaces. In the realm of bioabsorbable medical devices, the ongoing degradation due to corrosion can be explicitly accounted-for during the service life of the implanted devices. The randomized load patterns of a given virtual patient (or a population of patients) can provide the external loads necessary to perform simulated damage progression. This analysis could provide insights into the reliability of a temporary implant and its effect on a patient’s wellbeing.

Corrosion as the “Bad Guy”

Corrosion of a can

Image courtesy of sakhorn38 at FreeDigitalPhotos.net

The topic of corrosion makes recurring appearances in the media; it seems that when you hear about one corrosion-related problem, invariably there will be others reported-on at around the same time. There has recently been a spate of articles confirming that corrosion is currently a headache to the oil and gas sector (undersea bolt failures), as well as to the aviation sector (corrosion-induced fatigue of turbine engine blades in the new Dreamliner aircraft). Oftentimes these stories are first published by financial-leaning news outlets (Wall Street Journal, CNN Money, Bloomberg), a result of the high visibility and cost that these incidents bring in terms of replacement and downtime to their respective industries. Enough of these stories circulating over the span of a few news cycles will make any investor wary, and will prompt questions on what is being done from a regulatory standpoint to restore confidence in companies’ operations. This is particularly true when these reports of corrosion failures have impacts (real, or perceived) on public and environmental safety.

Of course, corrosion is not a new phenomenon. We have been observing the process of corrosion for centuries in our manmade structures, and have developed ways to physically mitigate its effects (painting, inspection methods, et cetera). However, it has only been in recent history that we a) have deeper understanding of the electrochemical processes that describe corrosion, and b) have the industrial engineering prowess to design and build ever greater machines and superstructures that help make modern life possible (economically-available energy sources and air travel, being prime examples). The confluence of these two factors drive the need for more development of mechanistic approaches to corrosion mitigation, through the use of computer-assisted modeling and simulation.

To that end, more and more resources are being appropriated for the research of these corrosion mechanisms in many of the materials that are used today. For example, members of the LIFT Consortium (Lightweight Innovations for Tomorrow) have begun work on the development of new models and a material properties database that will allow for more accurate simulations of corrosion in aluminum alloys used in aerospace and other transportation sectors (focusing on aluminum alloys containing copper, lithium, magnesium, manganese, and zinc). The materials database will be characterized to such a degree so that precise information is obtained about the interaction between microstructure and corrosion. The team will begin with the characterization of the industry’s workhorse alloys, and then extend work to evaluate newer alloys crated using various manufacturing techniques. The goal is to mitigate corrosion in a broad spectrum of aluminum alloys through improved simulator capabilities.

However, only half of the equation is being studied by LIFT: the corrosion impact on metals…with no discussion of how that corrosion introduces damage states, from which stress corrosion cracking and other types of corrosion-fatigue can arise. VEXTEC has pioneered development of a software for the U.S. Navy that predicts the statistical distribution of stress corrosion cracking in an alloyed aluminum microstructure that has been exposed to a corrosive environment. This software serves as a basis for all types of materials that are impacted by corrosion: the material modelers can provide the inputs of the corroded damage states into the VEXTEC software, which will in turn simulate the result of in-service loading on the durability of the critical structures of interest.

Until such time as corrosion has been completely removed as a mechanism in a critically-stressed component (and that time is not approaching anytime soon), it is enough to just model the corrosion characteristics…we must also be able to effectively model the subsequent damage growth throughout the component’s service life.

 

VEXTEC Presenting at Trelleborg’s 2016 Global FEA Meeting

August, 2016 – Dr. Sanjeev Kulkarni (VP, Sales & Business Development) and Dr. Robert Tryon (CTO) from VEXTEC Corporation will be presenting at the 2016 Global Finite Element Analysis (FEA) meeting for Trelleborg Sealing Solutions (TSS) to be held in Boston, MA on September 15. The presentation will discuss the “Implementation of ‘Integrated Computational Materials Engineering’ or ‘ICME’ towards Managing the Fatigue Life of Components and Assemblies”.

ICME combines computational modeling and materials engineering, and considers materials at multiple length scales, processes that produce these materials and the properties to predict and optimize the performance of components. VEXTEC characterizes materials at the microstructural level and uses its Virtual Life Management®  (VLM®) technology to understand material damage, flaw initiation and crack propagation towards estimating fatigue life in components and assemblies subject thermal / mechanical cyclic loads. The talk will discuss VLM in the context of industry recognized structural design philosophies: Safe Life and Damage Tolerance.

VEXTEC Presenting at International Conference on Fatigue Damage of Structural Materials XI

August 30, 2016 -Dr. Robert Tryon, CTO of VEXTEC, will be presenting at the eleventh biennial International Conference on Fatigue Damage of Structural Materials which will be held in Hyannis, Massachusetts beginning September 18th through the 23rd. This conference will bring together delegates from around the world to discuss how to characterize, predict, and analyze the fatigue damage of structural materials. Dr. Tryon’s presentation titled, “Microscale Computational Fatigue Modeling of Structures with Surface Corrosion” will be given, Tuesday, September 20th at 11:10 a.m.

Presentation for the 2015 SIMULIA West Regional User Meeting

Author:  Dr. Sanjeev Kulkarni, Vice President Sales and Business Development.

Dr. Sanjeev KulkarniLast week, I was at the 2015 SIMULIA West Regional User Meeting held at the historic Hayes Mansion in San Jose, CA! VEXTEC was one of the sponsors of the event and is a partner of the Advanced Integration Program. It was the 20th anniversary of this event and I was at the first of these events held in Long Beach. The longstanding tradition of the Regional User Meeting format has continued – providing an invaluable platform for industry and academia to join together and share their knowledge and experience in advancing methods and technology for finite element analysis, multi-physics, process automation, design optimization and simulation management . It was great to catch up with old friends (the Computational Modeling community is a small and close knit community), connect with other users and learn how the latest simulation technology and methods can accelerate and improve product development. At the meeting, I learned about Simulia’s Learning Community portal which is a convenient site to keep abreast of the latest collaborations in the 3DS eco-system.

The main event included future strategies and technology/product updates from Simulia leadership as well as User Presentations and Networking opportunities. I also had the opportunity to participate as an invited speaker. My talk entitled – Computational Modeling of Complex Systems using “Digital Twin” and “Digital Thread” Frameworks – underscored of how VEXTEC’s Virtual Life Management (VLM) technology compliments and aligns with Dassault Systèmes (DS) strategy of computational modeling and uncertainty management. VEXTEC is developing this technology as part of the US Air Force’s initiative on developing a computational Digital Thread, Digital Twin eco-system.

Here is a link to the slides from my presentation: VEXTEC DS SimuliaWest 2015_Presentation

VEXTEC Presenting Uncertainty Management at the 2015 ASME Verification & Validation Symposium

ASME V&V Symposium 2015 Program

ASME V&V Symposium 2015 Program

Brentwood, TN May 7, 2015 – Dr. Sanjeev Kulkarni, Vice President of Sales & Business Development of VEXTEC Corporation, will be presenting at the fourth annual ASME Verification & Validation Symposium in Las Vegas, NV on May 15, 2015.  The symposium, which runs from May 13 – 15, 2015, is entirely dedicated to verification, validation and uncertainty quantification (VVUQ) of computer simulations bringing together the foremost experts to exchange ideas and methods around for verification of codes and solutions, simulation validation and management of uncertainties in mathematical models, computational solutions and experimental data. Dr. Kulkarni is also chairing two sessions in the symposium, Validation Methods for Solid Mechanics and Structures (May 13) and Validation Methods for Impact, Blast, and Material Response (May15).

 

Dr. Kulkarni will be presenting, “VVUQ of Computational Modeling and Simulation Software To Predict The Durability Of Medical Devices”  which will discuss VEXTEC’s system reliability method and software, called Virtual Life Management® (VLM®). The VLM software considers the uncertainty of model parameters and acquired data to serve as a framework to incorporate realism with multi-scale statistical characterization using probabilistic and parallel computational simulation techniques.  The model itself, called a Virtual Twin®, characterizes parametric design sensitivity and uncertainty; both factors included in the proposed ASME V&V 40 Standard for Medical Devices. The talk will make that connection between VLM and ASME V&V 40.

 

The Virtual Twin, successfully implemented across multiple industries, starts with the initial preliminary design where it supports verification and validation activities and then is refined as the device moves through the detailed design, manufacturing, testing, launch and post market segments of the product life cycle. At any phase of the life cycle, the model considering uncertainty of any or all of the inputs to prognosticate the probability of device success in the future phases of the life cycle.

 

Founded in 2000, VEXTEC Corporation has developed patented technology on virtual material modeling and predicting product durability. As a senior strategic member of VEXTEC’s Leadership Team, Dr. Kulkarni leads commercial Sales & Business Development with a focus on Healthcare/Life Sciences/Medical Devices and Strategic Alliances. Dr. Kulkarni is an industry recognized leader and expert in Computational Mechanics and Computer Aided Engineering, and has supported many industries (Automotive, Aerospace, Defense, Energy, Consumer Products and Medical Devices) and in a variety of roles that include 5 years with Boston Scientific (as R&D Fellow), 10 years with KB Engineering (as President) and 6 years with TRW Automotive (as Principal Engineer).

VEXTEC Presenting at 14th Annual Design of Medical Devices Conference

VLM Software

VEXTEC’s VLM software for leads of defibrillator devices

Brentwood, TN, April 10, 2015 – Dr. Sanjeev Kulkarni, Vice President of Sales & Business Development of VEXTEC Corporation, will be presenting at the 2015 Design of Medical Devices Conference on April 15, 2015. The conference will be held in Minneapolis, Minnesota April 13 – 16. Representatives from world-class medical device designers, researchers, manufacturers, and the public sector will be in attendance to share perspectives and innovations in medical device design.

Dr. Kulkarni will be presenting, Uncertainty Management in Computational Simulations of Medical Devices” which will discuss VEXTEC’s software based uncertainty management tool to virtually manage the life of products.  VEXTEC’s Virtual Life Management® (VLM®) software uses efficient Monte Carlos simulation with system reliability methods to analyze risk and predict failure at component, system and population level for many types of products including medical devices. Based on the tool’s maturity in other industries, the FDA has accepted the tool into the Medical Device Development Tool (MDDT) pilot program. The VLM® tool considers the uncertainty of model parameters and acquired data to serve as a framework to incorporate realism with multi-scale statistical characterization using probabilistic and parallel computational simulation techniques. VEXTEC will also participate in the Scientific Poster Session on April 15

Founded in 2000, VEXTEC Corporation has developed patented technology on virtual material modeling and predicting product durability. As a senior strategic member of VEXTEC’s Leadership Team, Dr. Kulkarni leads commercial Sales & Business Development with a focus on Healthcare/Life Sciences/Medical Devices and Strategic Alliances. Dr. Kulkarni is an industry recognized leader and expert in Computational Mechanics and Computer Aided Engineering, and has supported many industries (Automotive, Aerospace, Defense, Energy, Consumer Products and Medical Devices) and in a variety of roles that include 5 years with Boston Scientific (as R&D Fellow), 10 years with KB Engineering (as President) and 6 years with TRW Automotive (as Principal Engineer).

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Today’s Warranty Challenge: Building Brand Loyalty While Delivering Better Products

According to the National Highway Traffic Safety Administration, last year the auto industry recalled close to a third more vehicles in the U.S. (22 million) than it sold (just over 15 million). Recalls were up by a staggering 25 percent during 2013, which is the industry’s highest rate since 2004. It is no shock that these recalls can do immense harm to a manufacturer. In the automotive industry, an early response to an emerging issue can save a tremendous amount of money, and help preserve a business’s reputation. Read more

The Need for Speed

In the race to get products to market, does risk-mitigation get enough time in the winner’s circle?

indy-blog-cover-imageWhat do aerospace, medical device manufacturers, and auto racing all have in common?  Answer: the need to minimize risk of premature/unexpected component failure while crossing the finish line first.  While these industries each have vastly different stakeholders, goals, and success metrics, all look to avoid costly breakdowns in the field.  And speed is key.  Being the first across the finish line in auto racing gives you the largest share of the purse, not to mention first choice of lucrative endorsement deals.  Being the first to market with an innovative or more reliable medical implant or a lighter aircraft component helps in marketing, product launch success, or company profitability and growth.  However, pushing the design limits to gain this speed advantage must be weighed against the possible failure of the component in an unforeseen manner.

Speed in Design

Auto racing is one of the world’s most expensive sporting endeavors.  A recent USA Today article puts the price tag of prepping and running a car in the Indianapolis 500 at nearly $1 million, and that is already assuming that the car is owned outright.  While the bulk of this cost is sunk into parts, staffing, and off-track expenses, a not-insignificant 4.5% of that is spent on controlled testing.  For example, one day at a rolling wind tunnel costs $35,000…more than the MSRP of the average production vehicle on US roadways today.  While the finances of auto racing and the commercial automotive industry may differ, their goals are similar: to create lighter-weight components that will aid (or at least not hinder) aerodynamic performance.  Designers are constantly being tasked with pushing the envelopes of their designs, while still attempting to maintain reliability and risk targets.  These designs, in turn, lead to more expensive and detailed manufacturing/machining techniques and the use of more exotic material alloys.  The uncertainties in every design usually manifest themselves as restrictive knock-down or safety factors that inevitably detract from performance.  Governing bodies in the various auto racing categories (F1, NASCAR, drag racing, to name a few) place additional restrictions in the form of specification limits on components such as engines, body shapes, and spoilers to maintain competitive balance.  Regardless of the type of restriction, if a way to reduce the uncertainty in a design is found, it can be advantageous.  VEXTEC’s Virtual Life Management (VLM) simulation technology can be that solution.  Through rigorous computational analysis of design, load-induced stress, and material, VLM can efficiently identify and quantify those design uncertainties.  VEXTEC has provided VLM support to many of the industry’s leading manufacturers of heavy duty engine connecting rods, engine blocks, and turbochargers.  This new insight has offered engineers the ability to understand where they really are on their design envelope, and how far they can push certain parameters, even before the first test piece is built.

Speed in Optimizing Maintenance

Weight savings and aerodynamics are, arguably, even more critical in the aerospace industry, where the civilian maintenance repair & overhaul (MRO) market is expected to be $56 billion this year.  Engine maintenance alone will take up about 40% of this valuation.  The cost of an unexpected catastrophic failure is much higher here than in the auto world.  But in order to reduce this risk, aircraft must be maintained and repaired.  And while they’re being maintained, they are not in the air delivering passengers, hauling freight, or making money.  So minimizing the downtime is crucial to keeping viable profit margins. VEXTEC has partnered extensively with civil and military aircraft users, employing VLM on a multitude of issues including: unitized wing structures (US Air Force), certifying weld-repaired engine blades (EB Airfoils) and resolving premature bearing failure (American Airlines).  The bearing study, for example, saved American Airlines about $4 million per year by avoiding the repair/replacement of their APU bearings.  The results from these and other studies provide our clients with knowledge they would not have otherwise been able to acquire, and allow for sound financial decisions to be made on fielded components.

Speed in Reliability

One of the fastest-changing industries is the medical device industry.  Technology is racing forward, minimizing invasiveness is driving the miniaturization of implantable devices (especially in heart rhythm monitors), while manufacturing methods are still trying to catch-up.  It seems that no other industry is as heavily scrutinized in terms of reliability and risk, at least in public perception. Medical implants are exposed to harsh internal environments, unpredictable stress and strain cycles, and oftentimes difficult installation procedures.  Yet these devices are counted-on to reliably elevate our quality of life on a daily basis.  The variability observed in material, vendor supply, and manufacturing all play a part in the reliability of the components that make up a medical device.  Through industry-directed capability studies, the VLM technology pioneered by VEXTEC has effectively modeled these sources of variability, virtually tested millions of components, and delivered reliability answers to as many “what-if” scenarios as design and materials engineers saw fit to explore.  The VLM approach reduces the number of blind alleys (ineffective combinations of material, design, and operational limits) that companies would have to travel down through the traditional design-build-test method, and focuses internal R&D resources on the combinations most likely to succeed in both manufacturing cost and operational reliability.

These three high-risk/high-reward sectors are not the only sectors that have benefited from VLM technology.  Indeed, any company looking to speed-up their design phase, reduce their warranty reserves, or just wanting to make more-informed decisions on how their products can best be sourced, manufactured, and used would benefit from a conversation with us.  The green flag has dropped…where are you in the field?

VEXTEC: Meeting the Need for Speed.