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#Post#: 1590--------------------------------------------------
Ten Biomechanical Animal Joints Enable Extreme Performance
DIR By: AGelbert
Date: January 3, 2024, 3:51 pm
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[center]Paper Digest: Ten Biomechanical Animal Joints Enable
Extreme Performance[/center]
December 19, 2023, 6:33 AM By
[glow=teal,2,300]👨‍🔬 Emily Reeves[/glow],
a biochemist, metabolic nutritionist, and aspiring systems
biologist. Her doctoral studies were completed at Texas A&M
University in Biochemistry and Biophysics. Emily is currently an
active clinician for metabolic nutrition and nutritional
genomics at Nutriplexity.
[center]
HTML https://evolutionnews.org/wp-content/uploads/2023/12/Epibulus_insidiator_2.jpg[/center]
Photo: A sling-jaw wrasse, by Alain Feulvarch, CC BY 2.0 , via
Wikimedia Commons.
In 2021, engineer and ID proponent, Stuart Burgess analyzed ten
linkage mechanisms in animal joints and published his review of
their mechanical functions in Bioinspiration & Biomimetics. He
chose animal joints such as fish jaws, knee joints, and bird
wings due to their extraordinary performance and the extensive
knowledge base regarding how they function. As a veteran
mechanical engineer, Burgess is well positioned to assess the
mechanics of animal joints. Notice how in the excerpt below, he
praises the optimality of animal joint design and notes the
potential for bio-inspiration from studying animal joints:
--- Quote ---
> Ten different linkage mechanisms are presented. They are
chosen because they cover a wide range of functionality and
because they have potential for bioinspired design. Linkage
mechanisms enable animal joints to perform highly sophisticated
and optimised motions. A key function of animal linkage
mechanisms is the optimisation of actuator location and
mechanical advantage. This is crucially important for animals
where space is highly constrained. Many of the design features
used by engineers in linkage mechanisms are seen in nature, such
as short coupler links, extended bars, elastic energy storage
and latch mechanisms. However, animal joints contain some
features rarely seen in engineering such as integrated cam and
linkage mechanisms, nonplanar four-bar mechanisms, resonant
hinges and highly redundant actuators. The extreme performance
of animal joints together with the unusual design features makes
them an important area of investigation for bioinspired designs.
--- End Quote ---
As Seen at Home Depot 🤠
You may have noticed a four-bar mechanical linkage mechanism if
you watched a scissor lift while shopping at Home Depot. That
four-bar linkage mechanism allows the lift to extend in order to
reach products on high shelves. Collapsing the scissor lift
reduces the amount of space the lift takes up. Four bar linkage
mechanisms have four bars and four pivot points. The length of
the bars may vary as well as how the bars move in relation to
each other. By using unique four-bar linkage arrangements, an
engineer can optimize mechanical movements. Key points about why
engineers use such mechanisms include:
Four-bar linkage mechanisms can increase force by utilizing bars
of different lengths.
They can improve rotation or optimize the direction of
compaction.
They move actuators away from the joint providing a mechanical
advantage and lowering the energy needed for motion.
In Burgess’s paper, the first four-bar linkage mechanism
discussed is the mammalian knee — a joint that has been
criticized as poorly designed. As an engineer Burgess is
familiar with constraints and design trade-offs. So he first
discusses what the mammalian knee requirements are. To
summarize, he says the knee must provide a 120o range of motion,
be load bearing, and prevent overextension. He explains how
through a clever design — an inverted four-bar mechanism — all
of these requirements can be accomplished. The four-bar
mechanism enables a large extension range, but also has an end
stop which locks the knee. This lock decreases the amount of
work required by the muscles to stand erect effectively making
standing up easier. Because there is a broad area of contact
between the femur and tibia, loads can be transferred through
the joint and bore. In the knee’s four-bar mechanism, the center
of rotation moves, which also provides advantages. When you
squat, the center of rotation of the knee joint shifts, which
reduces your muscular effort by 35 percent when you rise from
the squat position. If you thought squatting was difficult,
imagine how difficult it would be without this brilliant design!
Burgess points out that one noteworthy constraint for joints of
biological systems is that they are restricted from using a
shaft inside a hole due to the necessity of a growth and
development process. This relevant constraint applies to
engineers working to develop self-replicating machines.
The Bird Wing Joint
The second four-bar linkage mechanism discussed is the bird wing
joint. Have you ever wondered how birds can fly so long without
tiring? Burgess points out that this is due in part to the
brilliant engineering in the avian elbow joint, which enables
wing tucking and extension. Burgess notes that, according to
research done with seagulls, the elbow wing joint decreases 12.3
percent of a bird’s need for force during flapping.
Grasshoppers, dragonflies, and other insects generate lift by
flapping and rotating their wings at steep angles. Flapping
occurs at a frequency of 20 to 1,000 flapping cycles per second.
It’s no surprise that these organisms make such a whirring
sound! To accomplish such rapid movement, some incredible hinges
are obviously required. Burgess points out that many insect
wings have a small bar as part of their four-bar wing mechanism
which ends up magnifying the wing rotation. This means that even
minor movements on the insect’s body can cause a considerable
angle of movement in the wing. Of course, the insect’s body must
be correctly built to allow such mobility. Burgess also points
out that flapping happens at a resonant frequency, which
significantly reduces the inertial energy required to flap. This
is only feasible because of the insect’s body architecture.
Another category of four-bar linkage mechanisms Burgess
discusses is that of fish jaws. The first example he provides is
a sling-jaw wrasse. As it happens, my husband and I owned a
wrasse. Why? For the purpose of eliminating flatworms, vermetid
snails, and bristle worms from our 75-gallon salt water
aquarium. One can’t help but appreciate how incredibly well
designed the wrasse’s mouth is. The term “sling-jaw” refers to
the fact that these fish can hurl their jaws. Burgess notes that
one function of the design is to capture prey with a quick
suction approach. The second is that the sling-jaw design
minimizes the amount of swimming the fish has to do. Pushing the
jaw forward requires significantly less energy than swimming
forward when food is nearby. As I was able to observe, the mouth
of our wrasse extended so quickly and far that it made the fish
an exceptionally agile hunter. Within a month or so of adding
the wrasse to our tank, no pests remained — all thanks to the
excellent design of the sling-jaw wrasse.
Burgess also describes the four-bar linkage mechanism of the
mantis shrimp — a marine creature that punches to eat. The force
is produced by a four-bar linkage mechanism connected to a
biological battery. When the shrimp is ready to punch, it
relaxes a muscle, the latch is released, and the accumulated
elastic energy delivers 1000 N of force. That is several orders
of magnitude larger than the weight of the organism.
A Gift for Engineers
To conclude, the amazing design structures in organisms provide
engineers with inspiring templates for creating better products.
Burgess provides three specific examples where direct study
could pay impressive dividends:
Improved 3D modeling of avian wing joints has important
implications for aircraft wing design.
Jaw mechanisms may result in new and improved designs for
robotic clamping.
The punching mechanism of the mantis shrimp could inspire new
technology in the field of industrial design.
Burgess’s review has been downloaded over 8,000 times and cited
19 times. The high number of downloads and citations suggests
that there is a growing interest among researchers in using
nature’s design templates to solve technological challenges.
This indicates that biomimetics is becoming an increasingly
important field for innovation and advancement in various
industries. By studying the intricacies of natural mechanisms
like four-bar linkages, scientists can gain valuable knowledge
that to enhance human engineering practices. This
interdisciplinary approach encourages critical thinking and
innovation, ultimately benefiting various industries by
inspiring more efficient and sustainable designs.
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