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Topic: Stiffness


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In the News (Fri 14 Dec 18)

  
  Stiffness -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-11-05)
(The property of moving with pain or difficulty) Stiffness is the resistance of an (An elastic fabric made of yarns containing an elastic material) elastic body to deflection by an applied ((physics) the influence that produces a change in a physical quantity) force.
Stiffness is typically measured in (A unit of force equal to the force that imparts an acceleration of 1 m/sec/sec to a mass of 1 kilogram; equal to 100,000 dynes) newton/ ((prosody) the accent in a metrical foot of verse) metre.
The (Something inverted in sequence or character or effect) inverse of stiffness is compliance, typically measured in units of ((prosody) the accent in a metrical foot of verse) metre/ (A unit of force equal to the force that imparts an acceleration of 1 m/sec/sec to a mass of 1 kilogram; equal to 100,000 dynes) newton.
www.absoluteastronomy.com /encyclopedia/s/st/stiffness.htm   (234 words)

  
 neck stiffness   (Site not responding. Last check: 2007-11-05)
Nuchal rigidity refers to a stiffness that prevents bending of the neck and limits movement of the neck.
The long-term effects of a stiff neck depend on the underlying cause.
A person who has a stiff neck from an injury may need physical therapy, pain medication, and hot or cold packs to reduce pain and stiffness.
www.northmemorial.com /HealthEncyclopedia/content/3155.asp   (1071 words)

  
 ASB: ACUTE EFFECTS OF EXERCISE ON PASSIVE JOINT STIFFNESS   (Site not responding. Last check: 2007-11-05)
Passive stiffness in a human joint is due muscular factors attributed to actin-myosin filaments and connective tissue factors which can be attributed to fascia, ligaments and friction in the joint.
The stiffness and damping coefficients of the relaxed knee was determined with the subjects seated on a table.
Stiffness was calculated from the first two complete cycles of oscillation using the methods presented by Meirovitch (1975).
www.asb-biomech.org /onlineabs/abstracts96/ricard.html   (818 words)

  
 Arnett D - Arterial Stiffness and Hypertension
Pulse wave velocity measures arterial stiffness indirectly since it is influenced by a number of factors, including wall thickness, vessel radius, or blood density independent of arterial stiffness.
The stiffness index, similar conceptually to Ep, is the logarithm of the ratio of systolic to diastolic blood pressure divided by strain; it was developed to reduce the impact of pressure on the measurement of stiffness.
The arterial stiffness indices for a given individual are defined as the ratio of the change in intraluminal pressure to change in the arterial diameter over the cardiac cycle.
www.fac.org.ar /scvc/llave/hbp/arnett/arnetti.htm   (2352 words)

  
 Etherington & Roberts. Dictionary--stiffness   (Site not responding. Last check: 2007-11-05)
Resistance to the bending is called flexural stiffness, and may be defined as the product of the modulus of elasticity and the moment of inertia of the section.
Other factors being equal, stiffness of paper and board varies as the cube of its thickness and directly with the modulus of elasticity.
Stiffness is improved by increasing the degree of hydration of the pulp used in making the sheet, because a high degree of hydration makes paper dense and hard, and provides cohesive strength.
palimpsest.stanford.edu /don/dt/dt3340.html   (182 words)

  
 Stiffness   (Site not responding. Last check: 2007-11-05)
Moreover, for the reference orientation and a value of z=0, stiffness maps were obtained for all architectures and all directions of stiffness.
From Table 7, it is apparent that the (FA) architecture is superior to the others in terms of translational stiffness along all three axes.
In terms of rotational stiffness, the (MSP) architecture is clearly the poorest, having stiffnesses of 1/3 to 1/2 those of the other architectures.
wwwrobot.gmc.ulaval.ca /~ricard/Articles/Boston_asme_95/node10.html   (291 words)

  
 Stiffness of aorta predicts stroke deaths in hypertensive patients
Stiffness of aorta predicts stroke deaths in hypertensive patients
Arterial stiffness was gauged by measuring how long it took a pulse wave to move from the heart to other parts of the body (pulse wave velocity or PWV).
Aortic stiffness may increase pulse pressure (the difference between the upper and lower numbers in a blood pressure reading) thereby increasing the likelihood of heart disease and stroke; or the stiffness measurement may reflect damage in the artery wall, Laurent says.
www.eurekalert.org /pub_releases/2003-04/aha-soa033103.php   (260 words)

  
 New Positional Device
Stiffness is particularly advantageous in very small (sub micron) positional devices as thermal motion is a significant source of positional uncertainty.
The stiffness and thermally induced positional uncertainty of three designs -- a robotic arm, a Stewart platform, and one member of the new family -- are analyzed and compared.
Scaling laws imply that stiffness is adversely affected by reductions in size and so stiffness is at a premium in small devices, particularly in devices that are molecular in scale yet must be able to position molecular components with an accuracy of a fraction of a nm.
www.zyvex.com /nanotech/6dof.html   (3854 words)

  
 Prestin and the Dynamic Stiffness of Cochlear Outer Hair Cells -- He et al. 23 (27): 9089 -- Journal of Neuroscience
The amplitude of the fiber-driven motion is determined by the stiffness of the fiber and the cell.
The stiffness change is reflected by changes of the amplitude of the loaded-fiber motion during motility; the amplitude increased during cell contraction, and decreased during elongation with reference to the baseline (indicated by arrows).
in stiffness is 28% with SD of 11%.
www.jneurosci.org /cgi/content/full/23/27/9089   (6235 words)

  
 Extreme composite materials with negative stiffness inclusions
Particulate composites with negative stiffness inclusions in a viscoelastic matrix are shown to have higher thermal expansion than that of either constituent and exceeding conventional bounds.
In view of recent concepts of the continuum theory of elasticity, the banding instability of the foam in compression is considered to be a consequence of the non-monotonic relation between force and deformation of the single cell.
Negative stiffness entails a reversal of the usual codirectional relationship between force and displacement in deformed objects.
silver.neep.wisc.edu /~lakes/NegStf.html   (2129 words)

  
 Directory of open access journals
Measurement of the bending stiffness a healing fracture represents a valid variable in the assessment of fracture healing.
At ten weeks, bending stiffness of the tibiae were determined in a four-point-bending test device to validate the in-vivo-measurement data.
Measurement of stiffness data over time revealed a significant logarithmic increase between the third and seventh weeks, whereby the logarithmic rate of change among sheep was similar, but started from different levels.
www.doaj.org /abstract?id=81986&toc=y   (359 words)

  
 A Non-Cross-Bridge Stiffness in Activated Frog Muscle Fibers -- Bagni et al. 82 (6): 3118 -- Biophysical Journal
The data refer to the active tension developed at the time of the stretch and to the corresponding static stiffness measured in different contractions in which stretches were applied at different times after the start of stimulation.
Stiffness rises ahead of tension during the tetanus rise and falls ahead of tension during relaxation.
Note that the peak of static stiffness (indicated by the vertical dotted line) is reached ~10 ms after the start of stimulation (coincident with the first point plotted) when tension is still very small.
www.biophysj.org /cgi/content/full/82/6/3118   (6221 words)

  
 Stiffness   (Site not responding. Last check: 2007-11-05)
Stiffness maps were obtained for the reference orientation and a value of z=0, for all architectures and all directions of stiffness.
The results are shown in Table 6 where the minimum and maximum values of the stiffnesses in the reference x-y plane are listed.
From Table 6, it is apparent that the (FA) architecture is superior to the others in terms of translational stiffness along all three axes.
wwwrobot.gmc.ulaval.ca /~ricard/Articles/Delft_ceas_95/node9.html   (244 words)

  
 -- Neck, Back and Joint Stiffness
Massage, exercise, physical therapy and chiropractic treatments help spinal and joint stiffness and pain but the best results are obtained when combined with improving sleeping position, cleaning up lifestyle and correcting thyroid function to eliminate the inflammation and swelling in the tissues, spine and joints.
Since this is a slow process during years of abuse caused by an unhealthy toxic, lifestyle and improper posture and sleeping position, the cervical vertebrae 4 to 6 in the neck become fixated and subluxated.
Interference to the nerves and blood supply to the legs is caused over time by pressure on the nerves and blood vessels as a result of degenerative disease of the spine and discs caused by chronic irritation and inflammation caused by lifestyle related toxicity.
www.bodyzone.com /articles/article.html?id=20&pf=1   (2789 words)

  
 Chain Stiffness Testing, by Damon Rinard
Lateral stiffness of course, as any chain's vertical stiffness is virtually nonexistent, and even the most laterally stiff chain will quite easily flex vertically to wrap around even the smallest of cogs.
I measured the lateral stiffness of several chains by placing them on the garage floor with the axes of the pins level with the floor, then bending the chain to form an arc.
Lateral flexibility of the chain may be a benefit to modern multi-speed bikes, but a certain amount of lateral stiffness is sometimes needed on older derailleur bikes whose jockey pulleys are farther from the cogs.
www.damonrinard.com /chain_stiffness.htm   (682 words)

  
 Vibrational analysis and stiffness   (Site not responding. Last check: 2007-11-05)
In other words, the question is whether or not the stiffness of the metal would change if it was preloaded ahead of time.
For all practical purposes he told me to model the piece as a simple cylinder in one case with a horizontal force(preload) and without a horizontal distributed force.
I was under the impression that stiffness was a material property, and not subject to change based on loading condition.
www.engineersedge.com /Edge_disc3/0000003d.htm   (161 words)

  
 Stiffness   (Site not responding. Last check: 2007-11-05)
A team from Harokopio University in Athens found that both red wine, and wine that had the alcohol removed, reduced artery stiffness in 15 subjects with...
The Fine Cyclo units are characterised by their zero backlash, minimal lost motion (0.5 arcmin) and very high torsional stiffness, factors that ensure the...
As both the applied force and displacement are vectorss (respectively P and δ), in general their relationship is characterised by a stiffness matrix, k where:
www.wikiverse.org /stiffness   (270 words)

  
 Soil Stiffness Gauge for Soil Compaction Control - March/April Public Roads
In addition to the time and cost advantages, a portable soil stiffness gauge that is quick and easy to use will save lives and reduce exposure to injuries by enabling the technician to conduct each test rapidly.
The stiffness is the ratio of the force to displacement: K=P/d.
The new lightweight, portable soil stiffness gauge not only provides a means to measure the desired engineering property, but it is faster, cheaper, safer, and more accurate than the current standard methods.
www.tfhrc.gov /pubrds/marapr98/soil.htm   (2480 words)

  
 Stiffness   (Site not responding. Last check: 2007-11-05)
The stiffness of a body that a distance δ under an applied force P is:
Stiffness is typically measured in newton / metre.
The inverse of stiffness is compliance typically measured in units of metre / newton.
www.freeglossary.com /Stiffness   (270 words)

  
 Bicycle Frame Materials - Steel, Aluminum, Titanium and Carbon Fiber, by Sheldon Brown
Stiffness affects the riding qualities of a bike frame, since a frame suffers no permanent deformation in normal riding.
Stiffness is determined by a property of the material called "elastic modulus" Elastic modulus is essentially independent of the quality or alloying elements in a given metal.
Like stiffness, the specific gravity of a given metal is not significantly affected by the addition of different alloying elements.
sheldonbrown.com /frame-materials.html   (2293 words)

  
 Functions Of Fish Skin: Flexural Stiffness And Steady Swimming Of Longnose . . . (ResearchIndex)
To measure flexural stiffness, dead gar were gripped and bent in a device that measured applied bending moment (Nm) and the resulting midline curvature (m -1).
From these values, the flexural stiffness of the body (EI in Nm 2) was calculated before and after sequential alterations of skin structure.
Cutting of the dermis between two caudal scale rows significantly reduced the flexural stiffness of the body and increased the neutral zone of curvature, a region of bending without...
citeseer.ist.psu.edu /421866.html   (656 words)

  
 Joint stiffness
Joint stiffness can have many causes but most cases of joint stiffness are the result of normal changes of age.
If you experience these joint stiffness symptoms you may not be suffering from arthritis but there are other conditions, such as polymyalgia rheumatica, bursitis or tendenitis, that can cause joint stiffness.
Since high levels of PAF are associated with the aging process (and remember joint stiffness is often simply a result of aging), researchers believe that Ginkgo Biloba may slow the aging process.
www.godswaynutrition.com /productarticles/jointstiffness.html   (1580 words)

  
 Non-Destructive Determination of Stiffness of Asphalt Concrete   (Site not responding. Last check: 2007-11-05)
The aim of this project is to determine material stiffness of solids with large inhomogeneities.
Material stiffness of asphalt concrete depends on the frequency and the temperature.
For this kind of measurements the geometry and the boundary conditions of the asphalt concrete must be exactly known.
www.ifm.mavt.ethz.ch /research/eval-3.html   (342 words)

  
 Bending Stiffness
If you have a piece of board which is too stiff to flop, sellotape a pound coin to the end of each strip and then extend them over the edge of a table so that you can see which one bends more.
Equation [7] is the one used in two-point bending stiffness tests like the Taber, where the force required to produce a known deflection in a standard sized sample is measured.
The bending stiffness index is not necessarily improved because of the high density (and weight) of the coating.
www.ppfrs.org.uk /ianson/paper_physics/Bending_Stiffness.html   (2435 words)

  
 Wheel Stiffness Test
Lateral stiffness is how well a wheel resists flexing laterally (sideways) when a given load is applied in that direction.
There are plenty of parameters besides wheel stiffness that have a much larger bearing on bicycle performance, such as aerodynamics and training.
Besides flange spacing, the other parameters that could affect stiffness are often held constant between front and rear wheel pairs: number and gauge of spokes, and rim cross section.
www.sheldonbrown.com /rinard/wheel   (3523 words)

  
 Bending Spars with a Coke Can
The stiffness of the material is taken as being the slope of the straight line portion of this graph." Hmmm..., Mark is searching for stiffness of the material - in general.
In the table "Relative Stiffness and Weight of Spars" the column "Rem." indicates which data is based on my measurements (S) and which are from David's article (L).
The relative stiffness is the deflection of the reference spar divided by the deflection of target spar.
gamma.nic.fi /~sos/spars/cokecan.htm   (1699 words)

  
 joint stiffness pain   (Site not responding. Last check: 2007-11-05)
Offers joint stiffness pain with a product or service that delivers bone and joint pain and hiv joint pain.
Purecol capsules is a product that only contains 100% pure collagen, Purecol is 100% natural and has no side effects, it is in capsule form which is easy to take, the recommended dosage is 3 capsules a day to replenish your collagen levels.
EWe think we have a ground breaking product, with Purecol’s 100% collagen with added Aloe Vera and vitamin C, this combination helps more of the collagen to be absorbed directly into the joints to help repair depleted cartilage and relieve pain.
www.purecol.com /joint-pain/joint-stiffness-pain.html   (168 words)

  
 Stiffness: Less is More   (Site not responding. Last check: 2007-11-05)
Bubbles of negative stiffness material embedded in a more ordinary material may lead to composites with very high stiffness--perhaps good enough to improve airplane wings.
One way that engineers increase the stiffness of a material is to mix it with a second material to form a composite.
Instead of exerting the usual restoring force that tries to resist deformation, materials with a negative stiffness draw on the energy stored in their unstable equilibrium state to help the deformation proceed faster.
focus.aps.org /v7/st13.html   (554 words)

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