D.I.G. Jones was pivotal in research and development related to Air Film Damping System (AFDS) technology targeted at introduction of significant damping levels in rotating turbine engine blades.  

Some turbine engines experience significant lack-of-readiness due to maintenance issues.  A significant number of these maintenance issues are related to high-cycle fatigue (HCF) cracks which occur in engine rotating blade structure.  Generally, the crack issues occur due to excitation of blade resonances via engine rotation frequency and multiples thereof.  As engines are spooled up and down during operation, blades will be excited excessively as engine rotation orders coincide with blade resonance frequencies.  The effects of the induced stresses accumulate until eventually cracks develop in the blade structure.  At that point, the engine is out of operation and requires major maintenance.  This has been an enduring issue since the advent of the turbine engine.   Typical conventional damping systems targeted for these high-order dynamics, such as damped coatings, constrained layer damping systems,  particle-damping,  internal “dampers”, etc. do not survive the excessively high G-loads that exist within a turbine engine blade (80,000 G).  

D.I.G.  Jones was instrumental in developing AFDS technology which utilizes a very thin layer of ordinary air (impervious to the G-field) as the damping medium, whose properties are insensitive to temperature.  

AFDS was demonstrated to meet attenuation performance goals and durability goals during research and development efforts.    

AFDS is a truly unique resonance-response vibration attenuation technology brought to the world largely by D.I.G. Jones., as well as a couple of other individuals who will remain nameless at this time.

D.I.G. Jones created the Temperature-Frequency Nomogram format, which displays dynamic mechanical properties of viscoelastic materials as a simultaneous function of temperature and frequency, where the data can be curve-fit and later utilized with FEA and SEA modeling methodologies to design passive damping systems (for attenuation of resonance-response in structures).   This data format was a breakthrough in terms of quantifying the material properties of viscoelastic damping materials.  

David also worked research and development (in the 1980's and early 1990's)  related to the Arrhenius Alpha-T equation, which relates temperature and frequency effects for particular viscoelastic materials.   The Arrhenius Alpha-T equation can be varied via adjustment of a single parameter (the activation temperature).  So, varying the activation temperature while viewing the data set of dynamic mechanical properties (for a particular viscoelastic material) allows the engineer to define the unique relationship between temperature and frequency for the particular viscoelastic material.  This allows engineers to access modulus and material loss factor values characteristic of particular pairs of temperature and frequency.   The Arrhenius Apha-T is the "go-to" methodology for characterizing dynamic mechanical properties to this day.   This technology would not be available to the world without the contribution of D.I.G. Jones and a couple of other individuals, who will go nameless right now.

D.I.G. Jones contributed immensely to the development of passive damping system technology and to the application of viscoelastic (damping) materials to solve noise and vibration issues.   The technology would certainly not be a useful for noise and vibration control without David's contributions.  

Note that, in my youth, I personally generated many of the plots in the book shown on the left.  I distinctly remember the authors gathering at Anatrol Corporation in Cincinnati, Ohio to periodically work on the book in the early 1980s.

During my travels (structural dynamics engineer), I have seen these books (particularly the one on the left) on engineers' book shelves world-wide.  Both are excellent reference resources and are the best books on the subject that I know of.

David was a great engineer.  He was a rare technical powerhouse exhibiting great humility.   I was honored to work with him.  High points of my life occurred when David called me and asked me to work on Temperature/Frequency Superposition (for viscoelastic materials) in the 1980's and then Air Film Damping during the late 1990's. and early 2000's.  I learned a lot about structural dynamics, viscoelastic materials, and passive damping systems from David.   Mostly though, I learned a lot about life from him.  He was a great friend and mentor to me.  I will always miss him.      

Best wishes,

- TOM

(2/2)

Both of their unique and infectious laughs will live in my head forever, and I will continue to honor them by laughing my way through life, even at the toughest of times. I know they will be laughing with me at my side.

Pa truly was the epitome of a good man - a man all men and women alike should hope to be just a fraction of. He was vastly intelligent, yet remarkably patient, humble, generous, kind, and had such an endearing, goofy demeanor with a spirited personality that brightened any space he was in. He will continue to brighten our lives alongside Mamu, wherever they may be. As hard as it is to say goodbye for now, I find peace knowing the two of them can be together again at last - drinking coffee & tea, playing cards, eating donuts & candies, and visiting with all their beloved lost pets and mates while patiently awaiting us all to join them again.

Rest well, Pa. While our hearts ache at the immense loss of your physical form, your spirit lives on within each of us and each person you touched. I hope you know what a positively impactful man you were and continue to be. Give Mamu all our love - we will see you soon.

(1/2) 

It's a peculiar feeling to acknowledge how much of your life has been shaped by someone, and you may not fully realize it until they're gone. This couldn't be truer than in the case of Mamu and Pa, who were finally reunited just in time for their 62nd anniversary. My sense of humor continues to mirror both Pa and Mamu, as does my taste in food, drink, television, colors, jewelry, clothes, my love for all creatures (great and small?), and so on. To this day, I make bangers and mash almost once a week. I wear the same nighties Mamu used to wear later in her life. I have an ungodly amount of Flakes in the fridge from Pa, saving them for "rainy days" (the Penguins and Smarties were quickly demolished). I use the same instant coffee and tea as them daily, and I purchase strawberries, kiwi, pound cake, and artichokes whenever possible. I wear Mamu's jewelry on special occasions. We bought our single-story house to allow Pa to move around during visits easily. Their photos decorate our living room. It will be nearly impossible for the imprint they've left on us to falter - in fact, I anticipate it strengthening further in the coming years as we learn even more about them.

Mamu and Pa supported all my odd behaviors from the very beginning, calling me a "silly girl," but never hesitating to give me everything I desired to go about whatever I had on my mind. I can't count how many of Pa's old pill bottles I had in my closet, bottles he had generously donated to me to catch and release little bugs I found in the yard, including pill bugs themselves. Perhaps that's where my interest in pharmacy began? Ha! Throughout the years, as my sense of humor became less and less traditional and more so wildly inappropriate, they would just laugh and laugh, upgrading me to a "crazy girl," but not once saying I needed to tone my personality down.

Pa finally got his own coffee/tea station, decked out with cat paraphernalia! Complete with a microfridge! June 2024

Pa chuffed about his new cat-themed coffee station itemry for Father's Day! June, 2024

Pa and Cam hanging around the fire, Pa with his beloved Kindle! January 12, 2024

My earliest memories are of Pa, at the house on Lantern Hill. Watching him in the garden. ‘Helping’ him at his workbench. And Friday afternoons going to the bookstore and baskin robins for rocky road and the latest installment of mother Hubbard dog getting into shenanigans. I remember asking him for yet another bed time story and sneaking out of bed to watch him watch tv while Mamu slept on the sofa.  Over the years I grew up and left but home was where he was - my grandfather, and the best man I’ve ever known. 

The world is a lesser place without him in it. I can only hope to be half the person he was. 

I miss you pa.  And love you more than anything.

Pa with fresh baby Squish, January 23, 2024

Siannan's pharmacy school graduation, May 2023

Left to right to top, Jack's butthole, Bertrude, Pa, Clementine, December 27, 2022

Pa & Teeko living their best lives chilling upstairs while mom, Cam, and Siannan work downstairs, June 23, 2022

Pa Sleeping soundly at Siannan's, June 22, 2022

Pa enjoying a Christmas Eve dinner + mom and Cams wedding with us, December 24, 2021

Teeko proving that love can be earned, as was with Pa, December 26, 2021

Pa makin' his way to chill with Teeko, probably to watch us play wii golf, June 2019

Pa hanging around at Terrace, June 2019, featuring Bertrude (Albert)

Teeko & Pa napping peacefully in Story, August 2019

David, lovingly known as "Pa," was a remarkable human being who touched the lives of everyone he met. A highly accomplished and published aeronautical engineer, he specialized in vibration damping, a field he was deeply passionate about. Despite his impressive career, it was his kind and gentle nature that truly defined him. David had a way of brightening any room, always remaining positive, even in challenging times. He cherished his family, adored his cats, and had an undeniable sweet tooth.

David’s legacy of love and kindness continues through his daughter, Patti, his son, Chris, and his three grandchildren, Vanessa, Eirlyse, and Siannan. He is forever loved and will be deeply missed.

Siannan & Robert's NAU graduation, May 2019 - Pa looking chuffed

Siannan & Robert's wedding reception, chuffed

Pa giving Siannan away at their wedding (8/16/24) ♡

Siannan & Robert's wedding reception, Pa eating delicious wings and peanut chicken

OBITUARY

David Ioan Jones

5 November, 1936 – 4 September, 2024

Valley of the Sun Mortuary & Cemetery

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