VEXTEC Article Published in February Issue of Gear Solutions Magazine

VEXTEC article featured in February issue of Gear Solutions magazine

VEXTEC article featured in February issue of Gear Solutions magazine

Feb. 17, 2014 - Brentwood, Tenn. – The February issue of Gear Solutions Magazine features an article  from VEXTEC entitled “Using Integrated Computational Material Science to Create Virtual Simulations of Gear Fatigue Life.” The team of authors included Ganapathi Krishnan, Richard Holmes, Robert Tryon and Ed Pope of VEXTEC along with Richard Warns of Chrysler and Vikas Tomar of Purdue University. Former Purdue University Aeronautical Engineering Head Thomas Farris (Now Dean of Rutgers School of Engineering) and his graduate students also contributed.

Portions of the article describe work that was funded by the U.S. Naval Air Command.  The program paired VEXTEC’s probabilistic modeling capability (called Virtual Life Management or VLM) with Purdue’s CAPRI software, which models local surface stresses near contact points. Chrysler provided an extensive amount of test data of 9310 case hardened sun gears that were subjected to many demanding cycles on a dynamometer. Although designed to industry standards, about 4% of tested gears showed pitting damage.  VEXTEC’s simulations also showed that 4% of gears would suffer pitting damage.

The Navy was interested in using the VLM approach to analyze helicopter gears, which were made of Pyrowear 53. Notched, three-point bend data from technical reports were used to calibrate the model. Analysis was then performed on baseline gears, and those which had been superfinished to a very smooth surface.  Virtual Life Management showed that superfinishing more than doubled gear life.

The goal of the program was to develop a model that could quickly evaluate changes in design, material or processing. This was accomplished with probabilistic models that simulated the actual failure process. The benefits of this approach include (1) Reduced physical testing, (2) Accelerated research and development plus reduced time to market, and (3) Reduced warranty costs due to increased accuracy of life calculations. This approach can be used on all kinds of components, not just gears. To date it has been used in the aerospace, automotive, defense, electronics and medical device industries.

Click here to View the Full Article in Gear Solutions Magazine.


VEXTEC Awarded $800,000 Naval Corrosion Analysis Contract

Jan. 11, 2014 BRENTWOOD, Tenn. – VEXTEC recently received funding from the Office of Naval Research to continue work on “Corrosion Resistant Naval Alloys: Innovative Multi-Scale Computational Modeling & Simulation Tools.” This multi-year, $800,000 contract supports the Sea-Based Aviation National Naval Responsibility program.

VEXTEC will create software to serve as an integration tool that links the results of research on corrosion fatigue into a usable structural analysis tool. Fatigue failure due to corrosion is a multi-disciplinary, multi-scale problem. In order to accurately simulate this failure, integration of many mechanisms is required and better prediction of failure risk is necessary. The Navy’s objective is to take advantage of all available corrosion fatigue knowledge, methods, models and algorithms to fulfill this vision. The overall concept is to develop a tool set which has a library of different material microstructures, damage models, and solving routines to simulate corrosion fatigue failure. An additional feature of the tool is that it will allow users to integrate their own individual computational damage models or solving routines within the software tool. This feature will be analogous to most commercial finite element analysis (FEA) software tools that contain a library of their own different element types and solver routines for structural analysis, but also allow users to link their own special solving routines and specialized elements.


VEXTEC ( was founded in 2000 and has developed its patented technology on virtual material modeling and predicting product durability. VEXTEC offers its Virtual Life Management (VLM) services to a variety of commercial and government customers.


VEXTEC Corporation

Ashley C. Clark

Marketing Manager

(615) 372-0299 (ext. 233)

Product Reliability in the Medical Device Industry: Lab Testing Is Not Indicative of True Failure

Product Reliability in the Medical Device Industry: Lab Testing Is Not Indicative of True Failure

Brentwood, TN, August 28, 2013:  A recent TV commercial on medical implants caught my attention. While touting the benefits of extensive laboratory testing, the fine print said that “…results of the testing have not been proven to predict clinical wear performance…” How true. Laboratory testing is rarely indicative of true wear and does not predict actual product reliability in the medical device industry.

Testing is a necessary and vital element in the development of emerging device designs. However, testing alone in a laboratory setting is not adequate in guaranteeing the reliability of a device. Things that perform brilliantly in laboratory testing have been a disaster once deployed. A critical issue in certifying device reliability is the fact that in-patient failures often derive from non-typical damage conditions. One cannot test for high reliability. A failure rate as low as 1 in a 1000 can cause the manufacture to recall a device. At these rates, failures are driven by tails of the statistical distributions of loads, geometry and material properties. One just cannot test enough samples to understand what is going to cause failure in the patient population. One can test for “worst case” or accelerated failure conditions but it is difficult to know if worst case is 1/100, 1/1000 or 1/10000 failure rate. So it is not possible to quantify device reliability. Developmental testing at a specimen or sub-component level is required. These tests are useful in identifying gross design flaws, and the results of these tests must be used to calibrate or validate the full scale design models in the context of the actual usage conditions along with identifying important quality control parameters, but they cannot be used to predict reliability.

The medical device industry may have some catching up to do with regard to using additional tools to improve reliability and reduce recalls. The improvement in reliability in other industries has been driven by the use of computational models as an additional tool to physical testing and quality control. Computational models with probabilistic methods have been used in aerospace, automotive, civil structures and other industry to predict reliability and identify the most probable sets of conditions that will produce unacceptable failure rates. Computer aided design (CAD), finite element analysis (FEA), computational fluid dynamics (CFD), and material and manufacturing specification are combined to create a model that is a digital representation of the device such as the “Virtual Twin®” used in VEXTEC’s Virtual Life Management® (VLM®). The input values to the model are statistical distributions with estimated uncertainties. Automotive engineers use these models to computationally “drive the fleet” where the variation in manufacturing, usage, maintenance and repair are simulated to predict the incidents of failure of each of thousands of components. If a supplier produces a lot of 200 parts that do not meet a material specification, the model is ready to be used to simulate the risk of failure if the parts are accepted and put into production long before tests can be completed. Or even worse, if the 200 parts slipped through quality control, the models are ready to simulate risk and determine if a recall is required.

VLM recognizes the critical role of the random nature of damage accumulation in a population of patients. It provides a better means for using and assessing the results obtained from relatively few laboratory/animal/human tests which, by themselves, are unable to characterize the randomness that is critical to population-wide damage tolerance and risk assessment. VLM provides a technique for assessing the scatter in the behavior of clinical damage rather than simply relying on purely statistical safety factors for all operations. These empirical scatter factors do not differentiate between the sources of scatter such as patient type, patient activity level, damage type and locations, material lots and production methods. The safety factors today rely solely on the acquisition of great amounts of empirical field data thereby combining all factors in a single, undifferentiated life factor. The empirical approach means that the minimum life prediction capability often follows a critical recall, rather than anticipating it.

There was a feature article in Wired Magazine last November on the issue of product failure entitled “Why Things Fail”. The article provided a discussion of recall, warranty and reliability in various industries and what engineering does to try to avoid failures including computational simulations. But warranty is not just an engineering problem. Poor reliability and recalls reverberate throughout a company and even industries as discussed in the article.

Although computational simulation is not as wide spread in the medical device industry, the FDA would like to move the community in that direction. The FDA has hosted meetings on computational modeling ( At the last meeting, a featured speaker from NASA discussed how NASA requires probabilistic computational analysis as standard practice, this stemming from their very public failures. The FDA is also sponsoring the first annual conference on Frontiers in Medical Devices to focus on computational modeling (

The US Air Force, Navy, Army and NASA are taking this concept a step further in developing an airframe “Digital Twin”. This is a digital representation of an individual airframe (by tail number). This includes all of the engineering orders, repairs and missions that make each tail number unique. Uncertainty and errors associated with the manufacture, assembly, usage, record keeping and the computational models is all considered to “bound the uncertainty” on the health of the airframe. There could be a corollary to a future “Digital Patient”. The patents history, genetics, life style could used to create a model to simulate the risk of “failure” of a procedure or device.

Simulation-based design analysis is fundamentally about making decisions with uncertainty. The computational methods we advocate are for predicting reliability and managing uncertainty. VLM is a computational methodology that estimates the sensitivity of uncertainty in input variables and the sensitivity of modeling approximations to the final output. In the current age of large multidisciplinary virtual simulation, this is useful in determining how to optimize for the best use of computational and testing resources to arrive at most robust predictions of device reliability. As an example, with regards to implantable medical devices, one wants a high statistical confidence that the device is reliable before beginning patient trials. Too few samples are tested at a limited number of conditions to identify the subtle design issues that affect the reliability of the device once it is put into the market. This is understandable; one simply cannot test enough samples at enough conditions to cover all possibilities. It is also true that one cannot substitute modeling for testing, quality control or good engineering. However, computational models should be an addition tool in the engineer’s toolbox to drive up reliability and decrease the chance of a recall in the medical device industry.

Author:  Dr. Animesh Dey, VEXTEC Chief Product Development Officer

VEXTEC to Present at Inaugural Frontiers in Medical Devices Conference


Presenting at ASME's Frontiers in Medical Devices: Applications of Computer Modeling and Simulation Conference

Presenting at ASME’s Frontiers in Medical Devices: Applications of Computer Modeling and Simulation Conference


August, 20, 2013-VEXTEC ‘s Chief Technology Officer, Dr. Robert Tryon, and Dr. Animesh Dey, VEXTEC’s Chief Product Development Officer, will be making three presentations at the American Society of Mechanical Engineers (ASME) First Annual Conference on Frontiers in Medical Devices: Applications of Computer Modeling and Simulation, in Washington, D.C. September 11-13, 2013.

Dr. Tryon, who has spoken at previous medical device conferences, will discuss the use of VEXTEC Virtual Life Management®(VLM) simulation software in determining and improving product reliability. The presentation entitled “Computational Models to Predict the Structural Reliability of Aerospace Systems” will detail three VLM cases from the aerospace industry, which has a similar risk profile to the medical device market.  These examples involve a helicopter turbine wheel, an aircraft engine fan blade, and an auxiliary power unit of a commercial airliner.

The second presentation reflects a technical collaboration with Boston Scientific Corporation, Inc. The presentation, “Using Probabilistic Computational Durability Modeling and Simulation to Create a Virtual Design of Experiments Based on Limited Laboratory Tests”, will be presented by Dr. Sanjeev Kulkarni, R&D Fellow at Boston Scientific. Dr. Kulkarni participated in the collaborative program and applied the results to BSCI products. The presentation covers the use of VLM computational models to accurately simulate statistically large populations of medical devices.

The third VEXTEC presentation will be given by Dr. Animesh Dey who is a recognized expert in the field of Uncertainty Management. Dr. Dey’s presentation entitled “Confidence Estimates Due to Uncertainty in Multi-Disciplinary Computational Analysis”, details methods to propagate and manage the uncertainty in the computational models themselves as well as the data and information used as input into the models.


VEXTEC is a computational simulation company that provides computer aided engineering services and technical expertise in the areas of product development and in-service reliability.  The Virtual Life Management® (VLM) engineering software platform helps companies accelerate product development, reduce physical testing and speed time to market for new products, and resolve in-service product performance and reliability issues related to cyclic fatigue, wear and corrosion. VLM simulations explain why, how, when and where product damage will occur and what can be done to mitigate the situation and improve product reliability.


By:  Carl D. Kolts, VP of VEXTEC Corporation

The recent WSJ article “What’s Hot in Manufacturing Technology” provided a brief overview of computational tools that are accelerating technology advancements in product design and manufacturing. Some of these technologies are finding their way into the manufacturing mainstream today, such as 3-D printing, while others are several years if not decades away.

Modeling and simulating materials is an area that promises tremendous advantages in designing better products and getting them to market faster.  But practical application of material models built at the atomic or molecular level is still many years away.  VEXETC’s VLM (Virtual Life Management®) achieves many of the same benefits today by modeling microstructural behavior at the grain level. This is one step above the molecular level, but below the level typically used today by manufacturers, where a material is assumed to be homogeneous.

VLM is being used by manufactures today for new material development and the evaluation of new applications of existing materials.   VLM is used to reduce expensive, time consuming, make-it-and-break-it physical testing, while increasing insight into the behavior of the material in use, and confidence in the final design. As a computational tool, VLM also address the increasing need to control the variation in material design and processing.

To apply VLM a model or Virtual Twin® of a part is created.  The Virtual Twin is simulated by the VLM platform. This Virtual Twin captures the geometric design tolerances, the material variation, and the stresses the part will experience when in service. In this manner, VLM integrates the traditional material and structural design domains to provide a comprehensive understanding of component life under varying in-service conditions.

VLM provides insight into why damage occurs – how cracks and corrosion begin and grow over time. Sensitivity studies identify what can be done to prevent damage initiation and growth through modifications to material design, component design, processing, or in-service stresses. These sensitivity studies can show the effects of varying attributes like heat treatments, surface conditions, alloys, geometry, residual stress, or in-service loads and stresses. Think about how this can impact new product development and commercialization, as well as in service programs and warranties.

Consider the Cold Spray technology referenced in the WSJ article – VLM has been used to predict cold spray durability as an additive manufacturing technology to repair corrosion sensitive parts in multiple applications. Virtual Twins were configured and simulated to learn how damage would occur, and to predict the life of repaired parts based on the in-service usage conditions and material microstructure variations. Using VLM, the optimal cold spray repair configurations were determined without the need for expensive testing, before making the first prototype part.

VLM is a unique, patented technology that is used to accelerate product development and new product commercialization, as well as to understand and resolve complex in-service failure issues. It is being used across many industries, including aerospace and commercial aviation, medical devices, oil & gas, and automotive and industrial equipment applications. Manufacturing companies engage VEXTEC to apply VLM to minimize the uncertainty associated with manufacturing and in-service usage conditions and better manage risk.

Imagine being able to know when, where, and how damage and ultimately failure will occur in your product before ever making the first one. How can VLM impact your product development cycle, cost structure, and ability to manage risk and warranty reserve requirements?

To find out, give us a call or complete the contact request form below.

Integrated Computational Material Engineering for Virtual Life Management® of Medical Devices

DMD presentation by Dr. Robert Tryon, “Integrated Computational material engineering for Virtual Life Management of Medical Devices”

Click the slide above for the DMD presentation by Dr. Robert Tryon, “Integrated Computational material engineering for Virtual Life Management of Medical Devices”

April 2013 Design for Medical Devices Conference, Minneapolis, MN

by: Dr. Robert Tryon – VEXTEC CTO

Traditionally the design and development of medical device products has been largely based on extensive physical testing. Over the last few years advancements in computing power (cloud computing) and software capabilities such as FEA (finite element analysis) and ICME (Integrated Computational Material Engineering), have provided an avenue for the computational simulation of medical device performance. These computational tools can simulate the performance of a medical device under realistic conditions, thereby providing OEMs greater insight into potential product performance issues, and the opportunities to develop higher reliability products more quickly than traditional physical testing dependent methods.

Today these computational tools are in the early adoption stage within the medical device community, typically replacing some of the traditional test based design and analysis methods, thereby accelerating development and reducing costs. VEXTEC has been working with Boston Scientific Corporation to implement software that integrates computational structural engineering with computational material science to simulate the variations that can exist in a medical device and how these variations can influence product reliability and life. It’s called Virtual Life Management® (VLM).

Medical device manufacturers, working with government regulatory agencies have developed methods to assure the design of safe implantable medical devices. One test method cyclically loads the devices to replicate how they are stressed in the body to determine the fatigue life of the device. A “worst case” loading condition is usually employed and several dozen tests are typically required. These tests are useful in identifying gross design flaws; however the quantity of test samples is usually too small to identify the subtle design issues that affect the reliability of the product once it is put into the market. This is true not only in the medical device community, but in all industries as you simply cannot conduct enough physical testing at enough conditions to cover all possibilities.

To this point, there is tremendous variability in device application. Patient anatomy and lifestyles are different resulting in different loading conditions. Device installation techniques may vary. Subtle variations in device geometry and material homogeneity cause each individual device to respond differently even if the loading is identical. All of these variations combine to cause each device to have a performance level and expected life that may be revealed through premature failure.

With this understanding, it becomes clear there are several places where computational tools can be inserted into the current medical device design and analysis practice and provide valuable benefit. One obvious place is to simulate the testing of devices. Today cost and time constraints limit physical testing to a few samples and a few conditions. Virtual testing (simulation) can extend the actual testing to evaluate thousand of samples over many conditions quickly and economically. This allows manufactures to continue to use the same design analysis practice but with a more comprehensive set of “test data”.

The presentation, “Integrated Computational Material Engineering for Virtual Life Management® of Medical Devices,” was given by VEXTEC and Boston Scientific at the 2013 Design for Medical Devices Conference held at the University of Minnesota in Minneapolis. The presentation describes how VLM was used to conduct virtual fatigue testing and evaluate the durability of CRM pacing leads and airway stents under varying conditions. Scanning electron microscopes (SEM) were used to determine the variations in material microstructure and a limited number of laboratory tests were used to identify the material damage mechanisms. Finite element structural analysis was used to evaluate the device geometry and loading. These inputs were integrated with probabilistic computational material models within VLM to simulate literally thousands of lead and stent products. VLM can be continually used to evaluate a myriad of possible material – design – loading conditions in an effort to understand product limitations and facilitate the design of higher reliability medical devices.


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.  Continue reading