This white paper is intended to encourage simulation engineers to be good steward of their talent to understand the art of simulation. Additionally, I hope that the reader will also greatly appreciate the effect of "misusing" their talent to make a story that is not real or true whether such an activity is intentional or inadvertent. The question that I am urging the reader to ask himself or herself is this, "Can a person falling 2 inches while seating in a cushion seat have biomechanical damage to the spinal cord unless such a person has had a pre-existing condition such as a 'herniated disc' versus our own experience that people often times, even ourselves, have fallen a couple of feet as when we play the game of pulling a chair from our 'play frineds' unbeknownst to them and simply laugh when they 'fall flat on their posterior' but we never recall anyone of us being suit because 'our buddy filed a claim against us for 'pulling the chair causing the 'damaging fall" Seek the truth, report it the best one can, this is the essential ingredient of a truly objective analyst. "Yo Creo", the author's avatar (virtual) name, has the dual meaning, in Spanish, "I believe" and "I create". Therefore I encourage the reader of this paper to ponder on this idea, that simulating is an art in which one must believe that one can can create anything they set themselves to achieve; that is, a thought is a virtual world while the actualization of such thoughts create our physical reality.

1. Three types of lies; lies, damn lies and … simulations?
The title of this paper is “Three types of lies which should not apply to simulations” is intended to be an
apologetic report on behalf of all scrupulous modelers of physical events or simulators.
This short commentary is intended to blow the whistle on litigation settlement by insurance companies
based upon faulty simulations modeling and results from attorneys on behalf of their clients; whether
inadvertently or intentional. The case presented in this paper had been in my mind for fourteen (14)
years. When I first saw the article in the May 2000 issue of ASME I had waited to see whether there would
be any objections to its claims. To my knowledge none has been made.
Here is my perplexity of this case; I have a MSME from Tufts University, 1984 with computational
mechanics (simulations) core courses of study. As of this year, 2014, I have been creating and evaluating
thermo‐structural simulations for 30 continuous years and have never seen a credible simulation without
classical hand calculations to establish the boundaries of the proverbial, “Ball Park”. The case I am
presenting has many obvious flaws but to my surprise, even the ASME (American Society of Mechanical
Engineers) published the flawed‐simulation perpetuating the offense to investigators of physical events
via numerical simulation”.
I propose that the readers of this white paper will take it upon themselves to prove whether or not my
claims of inadequate simulation are true.

2. Like the Phoenix rising from the remaining ashes after a fire, it is my hope that students of simulations
methodology and practicing engineers would take this case as a benchmark of “erroneous zones” to be
understood and avoided in their own practice.
Having watched on TV two (2) separate beauty contestants fall on their posterior, without a “cushioned
seat” from full height without damage to their spines, then reading the article that a man falls two (2)
inches on a “cushioned seat” with consequential damages worthy of a law suit and the subsequent
publication of such a “Heroic simulation” in the ASME simply infuriated me that after fourteen (14) yeas
of contemplation decided to publish this white paper. Due to this misuse of simulation, I shall endeavor
to participate in any event that I can find in which simulations are being misused for financial gain by
attorneys and their clients. This area of simulation pertains to “Forensic Examination of Biomechanics
Claims of Bodily Damage Litigations”. The average weight, and height of a feminine beauty contestant is
120 lb (10 pounds lower than the average woman of the same height), and 5 feet 6 inches (66 inches) in
height, respectively. The following image can be used to establish an estimate of the height from the
ground to the bottom of the spinal cord
Reference: NASA‐STD‐3000, Vol. 1, Man‐Systems Integration Standards, page 3‐11 (81 of 801 in the PDF
file).
The height in inches corresponding to the bottoms of the buttock, 973 mm, is found by the linear ratio,
x/66” = 605 mm/ 973 mm. That is, x = 66” x (605/973) = 41.0”. Using this height for “Miss Beauty” and
multiplying it by the weight of 120 lb we get the potential energy (PE) at the time of being standing:
PE1 = w1 x h1 = 120 lbf x 41 inches = 4920 lbf‐in
The operator who claim that he was injured from a 2 inch fall while seating on a cushioned seat is 288 lbf
x 2 inches = 576 lbf‐in. The ratio of energy at the time of impact of “Miss Beauty” and “unfortunate
operator” is 4950/576 = 8.6. That is to say, “Miss Beauties had experienced an impact force 8.6 time
greater than that of the ‘unfortunate operator’ but did not report any injuries due to such a fall”.

3. My conclusion is that either the two (2) “Miss Beauty” contestants are actually “Bionic women” or the
man had a “pre‐existing condition such as herniated disc”. See detailed calculations starting on the next
page.
Let us think of the scenario where the “unfortunate operator” claim that he had his head resting on some
support system that failed and his head impacted the ground from a height of 2 inches; would anyone
believe him? How would one not believe the damage caused by a 2 inch drop of a person’s head onto a
rigid foundation while readily and implicitly admitting that the normal curvature of the snail cord would
not absolve most of the impact energy by means of the flexibility of spinal cartilage discs?
The only condition under which I would accept an injury claim from a 2‐inch fall is if the “unfortunate
operator” was “operating a rocket during take‐off and the seat broke at such an instant”.
The advices that apply to this case are extracted from the article published in BENCHmark magazine on
April 2001, page 11:
 Don't apply any model until the simplifying assumptions on which it is based are, fully understood
and the assumptions can be tested for applicability,
 Don't believe that the model is reality. A simulation no matter how complex is always subject to
the GIGO (garbage in, garbage out) rule. GIGO rule means that regardless of how accurate the
simulations model is, the output quality of the simulation results is ultimately governed by the quality
of the input data.
 Don't distort reality to fit the model. The model only represents results for the analyst to determine
correctness.
 Don't believe the second order consequences of a first-order model
I believe the model is flowed with subsequent erroneous results and conclusions due to being:
 Not having classical hand calculations to establish the limiting results such as potential energy
estimate. That is KE (Kinetic Energy) at time of impact equals the PE (Potential Energy) at the start
of the free fall.
 Not modeling the curvature of the spinal cord which would have required “beam elements”
instead of “truss elements”. The model simulates a “first‐order” phenomenon but the author used
such results to make a conclusion requiring “Second‐order simulation”.
SUMMARY: A computer model of a physical event is only good as the assumed governing equations,
constraint and input data. The model case being presented in this paper should be consider a
“benchmark” to avoid similar errors in our own digital simulation models.
CONCLUSION: The insurance companies should establish a forum where simulations analysts can be given
an opportunity to evaluate models submitted for claims keeping the litigants anonymously by not
mentioning their cases as either pending or resolved nor any identification of the litigants and their
attorneys. Group sourcing would enhance the discipline of simulations by allowing contributors to both
learn and teach the arts and sciences of simulations.

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. models. The trick is to determine the applicability, Amsterdam, Holland,
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BENCHmark April 2001 Page 11

36. Reprinted with permission from MECHANICAL ENGINEERING Magazine, 6/2000 © ASME International
• orenSIC
• exa Ina on
Engineering software backs the plaintiff's case In
a product laVsuit.
I T STARTED OUT as an ordinary
day at the TU Electric Oak
Hill strip mine near Tatum,
Texas. It became less than ordi­nary
when the excavating ma­chine's
seat pedestal collapsed.
It became serious when the
excavator operator reported
that the accident had inj ured
his lower back.
excavator seat pedestal of the
same part number. Mark Mann,
the lawyer who handled the case,
raised a new question that sent
Giesen seeking a solution: What
was the impact suffered by the
operator's lower spinal column
when his seat collapsed?
A VARIED BACKGROUIID
Giesen was associated with the
U.S. Air Force for 15 years, then
became involved in the private
sector aerospace industry. His
consulting business has given him
extensive experience in forensic
The strip mine's insurance
company brought a faulty­product
lawsuit against the
manufacturer of the excavator.
So it eventually became the
task of the Henderson, Texas,
law firm of Wellborn, Hous­ton,
Adkinson, Mann, Sadler
Hill LLP to prove that the me­A
close-up of the excavating machine's seat is shown with its engineering, along with a long
supporting pedestal. The suit arose when the pedestal failed. history of systems engineering
chanical failure of the seat caused the operator's lower
back injury.
RAISING A NEW QUESTIOII
When it took over the case, the firm contacted Herman
M. Giesen, a Dallas professional engineer and engineer­ing
consultant who had been researching the cause of the
failure. Giesen had been working first for the insurance
company itself, and then for a lawyer who had taken the
case before it came to Wellborn, Houston.
By that time, Giesen, an ASME member, had reviewed
design drawings and conducted a destructive test of an
This article was prepared by staff writers in collaboration
with outside contributors.
and mechanical systems design.
Pursuing an answer to Mann's question led Giesen to
his first practical experience with finite element analysis.
He eventually would use Mechanical Event Simulation
software from Algor Inc. to calculate and present a visual
reconstruction of impact forces, stresses, and oscillating
movement.
Giesen's research into the cause of the failure focused
on the seat's pedestal assembly, based on a witness's report
that the seat had apparently failed in the area of the tor­sion
assembly axle. The seat of the excavator rests on a
pedestal assembly that includes an adjustable torsion
spring scissors mechanism. This mechanism lets the op­erator
adjust the seat to a proper height to reach two
pedals and a hand manipulator comfortably.
Giesen was unable to study the seat pedestal actually

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This Mechanical Event Simulation model replicated the seat's dead-drop onto a stiff floor, showing the motion, flexing, and stresses involved in the impact.
involved in the accident, although he tried to recover
the seat at the mine site. He thought that it was buried
there, but it had been discarded, and a search of the site
failed to recover it.
Thus, instead of the original, Giesen decided to ac­quire
two seat pedestals of the same model and the
seat pedestal design drawings through the legal discov-ery
process.
By reviewing the design drawings, Giesen detected two
important facts about the design: The bearings that sup­port
the axles overhang the axle roots, and there are no
fillets at the roots of the axles. The effect of the first fact
is to create a significantly overhung load, which stresses
the root heavily under a bending load. This stress con­centration
at the root is further amplified by the second
fact-the absence of root fillets.
Failure to provide axle root fillets was a design flaw
and was the root cause of the failure and the operator's
injury, Giesen wrote in his final
port the axle was tapered and ragged, possibly because the
hole was punched in manufacturing.
The tapered axle hole would have allowed for an
axle root fillet radius of approximately 0.02 inch,
Giesen wrote. A fillet of that size would have signifi­cantly
reduced the stress concentration factor and,
hence, the likelihood of the failure. Alternatively, a
non-tapered hole would have better supported the axle
root as machined. Either way, it was unambiguously
clear that no relief had been specified in the machining
of the axle root.
By studying the drawings and by a destructive test of
one of his samples, Giesen became convinced that de­sign
and manufacturing flaws were causal factors in the
failure of the seat pedestal. When Mann came onto the
scene, he asked how much force was actually involved
in the impact.
Simple question, Giesen said, tough answer.
report. Had appropriate fillets SEEKING ANSWERS
been provided, the event most
probably would not have oc­curred.
Given these design flaws,
chronic cyclical and vibrational
stress are likely to cause fatigue
cracks to develop, propagate, and
cause failure.
As Giesen moved forward with
the destructive disassembly and ex­amination
of the sample seat
pedestal to confirm that there were
no fillets at the axle roots as manu­factured,
he also discovered that a
hole called for in the plans to sup-
Design and
lllanufacturing
flaws were cited as
causal factors in the
failure of the
In search of a practical method to
obtain the answer, Giesen talked to
a number of colleagues, who all
agreed that it was a tough problem
and, no, they didn't have any sug­gestions
to offer.
Since I am not an expert in me­chanical
analysis of this sort, I
sought the counsel of mechanical
analysis experts I respect, Giesen
said. From them I learned that
quantifying an impact force defies
traditional methods provided by
handbooks and calculations in
seat pedestal.

38. practical terms. You just
can't do it.
Giesen happened to
notice an advertisement
for Algor's Accupak/ VE
Mechanical Event Simu­lation
software, which
simulates motion and
flexing in mechanical
events, and computes
stresses.
the operator, 360 pounds,
was discounted by 20 per­cent
to account for the par­tial
support from his feet on
the pedals and his hands on
the controls.
Boundary conditions
fixed the hands where they
would grasp the manipula­tor
and the feet where
the heels would rest on the
floor. Beam and contact
elements represented the
knee and shoulder joints.
The spine consisted of
truss elements.
Although Giesen had
extensive experience in
mechanical and electro­mechanical
design and
systems engineering, he
didn't have any hands-on
experience with finite el­ement
analysis and simu­lation.
So he went to Al­gor's
Pittsburgh head­In
the assembled seat pedestal (top right), the axle is in the upper right corner of
the mechanism. The axle close-up at lower left shows no fillet at the axle root.
Although the human
spine naturally has a
curved shape, the spine
was modeled straight to
simplify the issue of im­quarters
to work with an applications engineer to devel­op
an impact model, over the course of three days.
Giesen used another Algor product, Superdraw III, to
develop the model following the manufacturer's design
drawings. He incorporated information about the oper­ator
as provided by the lawyer. Where numerical values
were not available, Giesen used conservative estimates
and varied them over several iterations.
The seat assembly was modeled in an upright position us­ing
three-dimensional beam, plate/shell, and solid brick el­ements.
The beam and plate/shell elements were used to
represent the steel base of the seat and were defined using
the material properties of steel from the software's Material
Library Manager.
The seat cushions were modeled using solid brick ele­ments
and were defined using a custom material. The
density of custom material was defined so that the seat
assembly would weigh a total of 120 pounds. Giesen re­searched
common material property values of poly­urethane
foams at the University of Pittsburgh's engi­neering
library to establish a reasonable range of Young's
moduli for the cushions. The Young's modulus of the
seat cushioning was one of the variables that would be
altered over a series of iterations.
Although the seat in the accident dropped 3 to 5 inch­es,
Giesen decided to model conservatively and so
assumed a 2-inch dead drop onto a stiff floor. The con­tact
between the seat and the floor was modeled using
Algor's proprietary contact elements, which enable engi­neers
to model how parts of a mechanism behave when
they come into contact.
SUDDEN IMPACT
A representation of the operator in an upright posture­perched
on the seat to reach the excavator's controls-was
then added to the seat assembly. The arms, legs, body, and
head were modeled using solid brick elements with a den­sity
so that the weight totaled 288 pounds. The weight of
pact force. If the backbone had been curved, it would
have deflected in the analysis, thus absorbing much of
the force, rather than calculating a total impact force as
was intended. The Young's moduli for the body parts
was based on biomechanical information resources, in­cluding
a telephone call from Algor's offices to an expert
in the field, and were varied over a series of iterations.
STANDARD GRAVITY LOADING
The complete model was subjected to a standard gravity
loading for the duration of one second, analyzed in 100
time steps. Giesen could watch the event unfold as it
was processed.
The software displays the movement of the mecha­nism
and stresses as they occur over time. Thus, Giesen
was able to vary the stiffness of the seat cushions and
body based on the behavior of the model.
He evaluated the results at the moment of impact in
gs, for force amplification factor, which is a factor of
how much a subject's body weighs at the time of im­pact.
Depending on the input variables, including
height, some of Giesen's models yielded an impact
force of as much as 5 and 6 gs. However, Giesen's final,
optimized model, with the 2-inch fall, yielded 2.24 gs.
Multiplying the estimated 288 pounds by the g force
gave the operator an effective weight of 645.12 pounds
at the moment of impact-a considerable load for the
human spine to bear.
Giesen followed the event step by step on his com­puter
screen and watched the force operating at points
on the body in real time. It was remarkable to see the
reverberation in very high mechanical frequency rip­pling
up and down the backbone, he said.
There was no need for Giesen to swear in and tell a
jury of his results. The report of his destructive exami­nation
and Mechanical Event Simulation results was
one of many considerations in the subsequent settle­ment
of the lawsuit. _