about pain and or loss of range of motion of a joint joint stiffness the term regarding the stability of a differential equation stiff equation Refimprove date May 2009 Stiffness is the resistance of an Elasticity ... property . Calculations The stiffness, k , of a body is a measure of the resistance offered ... or compression of a rod , the stiffness is defined as math k frac F delta math where F is the force ... System of Units , stiffness is typically measured in Newton unit newton s per metre . In English Units, stiffness is typically measured in pound force lbf per inch. Generally speaking ..., a M x M Matrix mathematics matrix must be used to describe the stiffness at the point. The diagonal .... In industry, the term influence coefficient is sometimes used to refer to the coupling stiffness ..., for a cantilevered beam, the stiffness at its free end is 12 E I L 3 rather than 3 E I L 3 ... , to calculate a particular direct related stiffness the diagonal terms , the corresponding Degrees ... the direct related stiffness for the degree of freedom which is unconstrained. The ratios between ... inverse inverse of stiffness is compliance , typically measured in units of metres per newton ... pascal unit Pa . Rotational stiffness Torsional rigidity redirects here A body may also have a rotational stiffness, k , given by math k frac M theta math where M is the applied moment physics moment &theta is the rotation In the SI system, rotational stiffness is typically measured in newton metre s per radian . In the SAE system, rotational stiffness is typically measured in inch pound force pound s per degree angle degree . Further measures of stiffness are derived on a similar basis, including shear stiffness ratio of applied shear stress shear force to shear deformation torsional stiffness ... In general, elastic modulus is not the same as stiffness. Elastic modulus is a property of the constituent material stiffness is a property of a structure. That is, the modulus is an intensive and extensive ... more details
For the stiffness tensor in solid mechanics, see Hooke s law Matrix representation stiffness tensor . In the finite element method and in analysis of spring system s, a stiffness matrix , K , is a symmetric matrix symmetric positive semidefinite matrix that generalizes the stiffness of Hooke s law to a matrix, describing the stiffness of between all of the degrees of freedom so that math mathbf F K mathbf x math where F and x are the force and the displacement vectors, and math U frac 1 2 mathbf x top K mathbf x math is the system s total potential energy. For a simple spring network, the stiffness matrix is a Laplacian matrix in order to enforce Newton s third law describing the Connectivity graph theory connectivity graph between degrees of freedom. Off diagonal entries contain math k ij math , the negative stiffness of the spring connecting degree of freedom i to j . For example, math K left begin array rrrrrr 13 & 1 & 0 & 0 & 12 & 0 1 & 3 & 1 & 0 & 1 & 0 0 & 1 & 2 & 1 & 0 & 0 0 & 0 & 1 & 3 & 1 & 1 12 & 1 & 0 & 1 & 14 & 0 0 & 0 & 0 & 1 & 0 & 1 end array right math See also Hooke s law Mass matrix mathapplied stub Category Matrices zh ... more details
Artery Arteries stiffen as a consequence of age and arteriosclerosis . Age related stiffness occurs when the elastic fibres within the arterial wall elastin begin to fray due to mechanical stress. The two leading causes of death in the developed world, myocardial infarction and stroke , are both a direct consequence of atherosclerosis. Increased arterial stiffness is associated with an increased risk of cardiovascular events. The World Health Organisation predicts that in 2010, cardiovascular disease will also be the leading killer in the developing world and represents a major global health problem. Once considered by the ancient Greeks as inert conduits within which air flowed, William Harvey is generally credited with being the first to describe the circulation of the blood through arteries. When the heart contracts it generates a pulse or energy wave that travels through the circulation. The speed of travel of this pulse wave pulse wave velocity or PWV is related to the stiffness of the arteries. Other terms that are used to described the mechanical properties of arteries include elastance , or the reciprocal inverse of elastance, compliance. The relationship between arterial stiffness and pulse wave velocity was first predicted by Thomas Young in his Croonian Lecture of 1808 ref http www.jstor.org stable 109672?cookieSet 1 Young T On the function of the heart and arteries The Croonian ... that measure arterial stiffness parameters augmentation index, pulse wave velocity . These include ... Meas, 2009, 31, R1 R47 ref . The Pathophysiology of Arterial Stiffness The primary site of damage following an increase in arterial stiffness is the heart. Moreover, the means by which arterial stiffness causes damage to the heart are several fold. Firstly, stiffened arteries interrupt the Windkessel ... stiffness also repositions the site of pulse wave reflections. These reflections are an inevitable ... diseases DEFAULTSORT Arterial Stiffness Category Cardiovascular diseases Category Angiology ... more details
The spin stiffness or spin rigidity or helicity modulus or the superfluid density for bosons the superfluid density is proportional to the spin stiffness is a constant which represents the change in the ground state energy of a spin system as a result of introducing a slow in plane twist of the spins. The importance of this constant is in its use as an indicator of quantum phase transitions specifically in models with metal insulator transitions such as Mott insulators . It is also related to other topological invariant s such as the Berry phase and Chern number s as in the Quantum hall effect . Mathematically Mathematically it can be defined by the following equation math rho s cfrac partial 2 partial theta 2 cfrac E 0 theta N theta 0 math where math E 0 math is the ground state energy, math theta math is the twisting angle, and N is the number of lattice sites. Spin stiffness of the Heisenberg model See also Heisenberg model quantum l1 Heisenberg model Start off with the simple Heisenberg spin Hamiltonian math H Heisenberg J sum i,j S i z S j z cfrac 1 2 S i S j S i S j math Now we introduce a rotation in the system at site i by an angle sub i sub around the z axis math S i longrightarrow S i e i theta i math math S i longrightarrow S i e i theta i math Plugging these back into the Heisenberg Hamiltonian math H theta ij J sum i,j S i z S j z cfrac 1 2 S i e i theta i S j e i theta j S i e i theta i S j e i theta j math now let sub ij sub sub i sub sub j sub and expand ... axis Then since the spin stiffness is related to the difference in the ground state energy by math ... of the spin stiffness of the spin 1 2 Heisenberg antiferromagnet on square, triangular, and cubic lattices ... Bedell title Direct calculation of spin stiffness for spin 1 2 Heisenberg models journal Physical Review ..., H.J. Schulz title Direct Calculation of the Spin Stiffness in the J sub 1 sub J sub 2 sub ... Microscopic calculation of the spin stiffness constant for the spin 1 2 square lattice Heisenberg antiferromagnet ... more details
Infobox Disease Name PAGENAME Image Caption DiseasesDB ICD10 ICD10 M 25 6 m 20 ICD9 ICD9 719.5 ICDO OMIM MedlinePlus eMedicineSubj eMedicineTopic MeshID Joint stiffness may be either the symptom of pain on moving a joint, the symptom of loss of range of motion or the Sign medicine physical sign of reduced range of motion. Doctors prefer the latter two uses but patients often use the first meaning. br Pain on movement is commonly caused by osteoarthritis , often in quite minor degrees, and other forms of arthritis. It may also be caused by injury or overuse and rarely by more complex causes of pain such as infection or neoplasm. The range of motion may be normal or limited by pain. Morning stiffness pain which eases up after the joint has been used, is characteristic of rheumatoid arthritis . ref cite pmid 15338490 ref Loss of motion symptom the patient notices that the joint or many joints do not move as far as they used to or need to. Loss of motion is a feature of more advanced stages of arthritis including osteoarthritis , rheumatoid arthritis and ankylosing spondylitis . Loss of range of motion Sign medicine sign the examining medical professional notes that the range of motion of the joint is less than normal. Routine examination by an Orthopedic surgery orthopaedic surgeon or rheumatologist will often pay particular attention to this. The range of motion may be measured and compared to the other side and to normal ranges. This sign is associated with the same causes as the symptom. In extreme cases when the joint does not move at all it is said to be ankylosis ankylosed . See also Flexibility anatomy References reflist Arthropathies and related conditions Acquired musculoskeletal deformities disease stub Category Arthropathies ... more details
The bending stiffness math E I math of a Beam structure beam or a Plate metal plate relates the applied bending moment to the resulting deflection of the beam. It is the product of the elastic modulus math E math of the beam material and the area moment of inertia math I math of the beam cross section. According to elementary beam theory , the relationship between the applied bending moment math M math and the resulting curvature math kappa math of the beam is math M E I kappa E I frac mathrm d 2 w mathrm d x 2 math where math w math is the deflection of the beam and math x math the spatial coordinate. In the literature sometimes the above definition is given with a minus sign depending on convention. See also Beam theory Bending Applied mechanics External links http www.efunda.com formulae solid mechanics beams theory.cfm Efunda s beam calculator Category Continuum mechanics Category Structural analysis ... more details
Multiple issues unreferenced November 2006 notability May 2010 orphan November 2009 In computational mechanics , a tangent stiffness matrix is a matrix that describes the stiffness of a system in response to small changes in configuration. It represents tangent in that the energy of the system can be thought of as a high dimensional surface with the local slope of a plane tangent to it at the given point defined by the tangent stiffness matrix. The tangent stiffness matrix appears when solving certain problems. For example, the tangent stiffness matrix is the generalization of slope that can be used with Newton s method . See also Linearization Stability derivatives Category Mechanics Physics stub ... more details
As one of the methods of structural analysis , the direct stiffness method DSM , also known as the displacement method or matrix stiffness method , is particularly suited for computer automated analysis ... use of the members stiffness relations for computing member forces and displacements in structures. The direct stiffness method is the most common implementation of the finite element method FEM . In applying ... at the nodes. The material stiffness properties of these elements are then, through Matrix mathematics ... by solving this equation. The direct stiffness method forms the basis for most commercial and free source finite element software. The direct stiffness method originated in the field of aerospace . Researchers ... theory , energy principles in structural mechanics , flexibility method and matrix stiffness method . It was through analysis of these methods that the direct stiffness method emerged as an efficient ... stiffness method as an efficient model for computer implementation harv Felippa 2001 . Member stiffness relations A typical member stiffness relation has the following general form math mathbf Q ... k m math member stiffness matrix which characterises the member s resistance against deformations ... , which is used in the flexibility method . System stiffness relation See also Stiffness matrix For a system with many members interconnected at points called nodes, the members stiffness relations ... s nodes. math mathbf K math system stiffness matrix, which is established by assembling the members stiffness matrices math mathbf k m math . math mathbf r math vector of system s nodal displacements ... is established by assembling the members math mathbf Q om math . Solution The system stiffness ... consideration. The direct stiffness method It is common to have Eq. 1 in a form where math mathbf ... is then known as the direct stiffness method. The advantages and disadvantages of the matrix stiffness method are compared and discussed in the flexibility method article. Example Breakdown ... more details
Unreferenced stub auto yes date December 2009 The matrix method is a structural analysis method used as a fundamental principle in many applications in civil engineering . The method is carried out, using either a stiffness matrix or a flexibility matrix. The flexibility method is not conducive to computer programming Weaver, Gere . See also Direct stiffness method Flexibility method DEFAULTSORT Matrix Method Category Structural analysis Civil engineering stub es M todo de matriz ... more details
Volkmann may refer to A.W. Volkmann German physiologist Robert Volkmann German composer Elisabeth Volkmann German actress Richard von Volkmann German surgeon Volkmann s contracture Disease causing stiffness of the hand Volkmann s canals Microscopic structures in animal bone disambig de Volkmann pl Volkmann ... more details
The Shell pavement design method is used in many countries for the design of new asphalt road s. ref http www.mrr.dot.state.mn.us research apt data cs10 05.pdf The Stiffness Relation in the Rutting Prediction Module of the Shell Pavement Design Method ref In structural road design , the main considerations consist of soil parameter s, parameters thickness and stiffness for the other road Foundation engineering foundation materials, and the expected number of times a standard load will pass over. The output of the calculation is the thickness of the asphalt layer. ref Shell Pavement Design Manual Asphalt Pavements and Overlays for. Road Traffic. Shell International Petroleum Company, Ltd., London,. England, 1978 ref References Reflist Category Pavements road stub ... more details
wiktionarypar Rigidity Rigid Rigid or rigidity may refer to Stiffness , the property of a solid body to resist deformation, which is sometimes referred to as rigidity Structural rigidity , a mathematical theory of the stiffness of ensembles of rigid objects connected by hinges Rigidity electromagnetism , the resistance of a charged particle to deflection by a magnetic field Rigidity mathematics , a property of a collection of mathematical objects for instance sets or functions Rigidity neurology , an increase in muscle tone leading to a resistance to passive movement throughout the range of motion Rigidity psychology , an obstacle to problem solving which arises from over dependence on prior experiences Ridgid , a brand of tools disambig ar cs Rigidn de Rigidit t fr Rigidit ja sr ... more details
Wiktionary Compliance can mean In mechanical science, the inverse of stiffness Compliance medicine , a patient s or doctor s adherence to a recommended course of treatment Compliance physiology , the tendency of a hollow organ to resist recoil toward its original dimensions Regulatory compliance , adherence to standards, regulations, and other requirements Compliance psychology , responding favorably to a request offered by others See also Governance, risk management, and compliance disambig de Compliance fr Compliance it Acquiescenza disambigua ja ... more details
orphan date March 2009 In material science , the yield curve describes the behaviour of a plastic material . In a two dimensional stress system i.e. given forces acting upon a material from two directions the pliability or stiffness of the material can be plotted on a graph in the form of a yield curve. The curve expresses the failure stress, the combination of stresses at which the material yields, or cracks. The area inside the curve, accordingly, represents a safe combination of stresses for this material. References reflist Category Materials science engineering stub ... more details
disambig In handwriting analysis graphonomics a Movement parameter includes slant handwriting Slant , Orientation , Amplitude , Roundness handwriting . In kinesiology a Movement parameter is an adjustable scalar physics scalar quantity to be specified in a motor system , i.e. movement control system See kinesiology , graphonomics . Examples are Velocity , Acceleration , Force , Stiffness . Category Penmanship Category Motor control writingsystem stub ... more details
In relation to biomechanics , the aggregate modulus Ha is a measurement of the stiffness of a material at equilibrium when fluid has ceased flowing through it. The aggregate modulus can be calculated from Young s modulus E and the Poisson ratio v . math Ha E 1 v 1 v 1 2v math Reference Biomechanics of Cartilage by Mansour Category Biomechanics Category Motor control Category Physical quantities ... more details
to Torsion mechanics torsion and forced to twist. The bar resists the torsion through its stiffness. The stiffness of an anti roll bar is based on the fourth power of its radius, the stiffness of the material ... stiffness, which is a function of the spring rate of the vehicle s springs and of the anti roll bars ... roll stiffness of the vehicle. Increasing the total roll stiffness of a vehicle does not change ... behavior can be tuned out by changing the proportion of the total roll stiffness that comes from the front and rear axles. Increasing the proportion of roll stiffness at the front will increase ... effect. Increasing the proportion of roll stiffness at the rear axle will have the opposite effect and decrease ... , which increase in severity with the diameter and stiffness of the sway bars. Excessive roll stiffness, typically achieved by configuring an anti roll bar too aggressively, will cause the inside ..., such as in JGTC . This allows the stiffness to be altered by increasing or reducing the length of the lever arms. This permits the roll stiffness to be tuned for different situations without replacing ... more details
Elastography is a non invasive method in which stiffness or strain image s of soft tissue are used to detect or classify tumors . A tumor or a suspicious cancer ous growth is normally 5 28 times stiffer than the background of normal soft tissue. When a mechanical compression or vibration is applied, the tumor deforms less than the surrounding tissue. i.e. the strain in the tumor is less than the surrounding tissue. Hence a strain image may, under particular simplifying assumptions, be interpreted as representative of the underlying Young s modulus distribution. The strain distribution may be temporally variant in the presence of internal fluid flow. Elastograms images of tissue strain have been shown to be affected by the degree of adherence of the tumor to its surroundings, indicating a potential to extend elastography to tumor mobility characterisation to improve diagnostic accuracy and surgical guidance. Medical Imaging Ultrasound Ultrasonic imaging is the most common medical imaging technique for producing elastograms. Some research has been conducted using magnetic resonance elastography magnetic resonance elastography MRE and computed tomography . However, using ultrasound has the advantages of being cheaper, faster and more portable than other techniques. Transient elastography is used for example to measure the stiffness of the liver in vivo FibroScan, Echosens, France . It is an alternative noninvasive method to liver biopsy . A correlation between liver elasticity and the fibrosis score or cirrhosis has been shown. ref cite journal author Ganne Carri N, Ziol M, de Ledinghen V, et al. title Accuracy of liver stiffness measurement for the diagnosis of cirrhosis in patients ... of the breast ultrasound examination because tissue stiffness gauges of various types have been ... stiffness may boost breast imaging specificity. Diagnostic Imaging. 2009 31 12 15 17. ref http www.siemens.com ... ARFI Imaging is another imaging modality being researched to non invasively characterize liver stiffness ... more details
File Bicycle tire lateral force vs distance rolled.png thumb right Plot showing lateral force building up as a bicycle tire rolls forward at a 2.4 slip angle. The results from three separate test runs are superimposed. Relaxation length is a dynamic property of pneumatic tire s that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady state value. ref name Pacejka cite book title Tyre and vehicle dynamics last Pacejka first Hans B. authorlink Hans B. Pacejka year 2006 edition 2nd publisher SAE International pages 22 quote The relaxation length ... is an important parameter that controls the lag of the response of the side force to the input slip angle. isbn 978 0768017021 ref It is also described as the distance that a tire rolls before the lateral force builds up to 63 of its steady state value. ref name Cossalter cite book title Motorcycle Dynamics edition Second last Cossalter first Vittore year 2006 pages 58 quote The relaxation length represents the distance the wheel has to cover in order for the lateral force to reach 63 of the steady state force. publisher Lulu.com isbn 978 1 4303 0861 4 ref It can be calculated as the ratio of cornering stiffness over the lateral stiffness where cornering stiffness, another dynamic property, is the ratio of cornering force over slip angle, and lateral stiffness, a static property, is the ratio of lateral force over lateral displacement. Values Relaxations lengths have been found to be between 0.12 and 0.45 meters, with higher values corresponding to higher velocities and heavier loads. ref name Cossalter Tests on motorcycle tire s have found that the ratio of cornering stiffness over lateral stiffness produces values 20 25 higher than those calculated as 63 of the steady state value. ref name Uil cite web url http alexandria.tue.nl repository books 626939.pdf title Non lagging effect of motorcycle tyres An experimental study with the Flat Plank Tyre Tester author R.T. ... more details
Unreferenced stub auto yes date December 2009 Infobox Automobile image Image Lotus 27 2.jpg 250px name Lotus 27 manufacturer Team Lotus production 1963 predecessor Lotus 22 successor class Formula Junior body style Open wheel car Open wheel engine 1097 cubic centimeter cc Ford Cosworth transmission 5 speed manual Hewland transmission Lotus 27 was a Formula Junior version of the Lotus 25 Formula One car for the 1963 Formula Junior season. All aluminum monocoque with steel bulkheads. Originally designed with fibreglass sides which lead to stiffness problems, leading to them being replaced with aluminium. The Team Lotus cars were run by Ron Harris, and Peter Arundell won the 1963 British championship after the initial stiffness problems were solved. Lotus Category Lotus vehicles 27 Category Formula Junior cars Category Tasman Series cars Motorsport stub fa fr Lotus 27 it Lotus 27 ... more details
systolic wave. RT S35 is related to the stiffness of the aorta. The difference of the amplitudes ... on both the stiffness of the aorta arteriosclerosis and about the peripheral vascular tone. The closing ... in diastole. Increased and abnormal arterial stiffness is the early sign of arteriosclerosis. The arterial stiffness is calculated from the above parameters, resulting in a classification of optimal ... more details
In materials science , Composite laminates are assemblies of layers of fiber fibrous composite material s which can be joined to provide required engineering properties, including in plane stiffness , bending stiffness , Strength of materials strength , and coefficient of thermal expansion . The individual layers consist of high Elastic modulus modulus , high strength fibers in a polymer polymeric , metal metallic , or ceramic matrix material. Typical fiber s used include graphite , glass , boron , and silicon carbide , and some matrix materials are Epoxy epoxies , polyimide s, aluminium , titanium , and Aluminium oxide alumina . Layers of different materials may be used, resulting in a hybrid laminate. The individual layers generally are orthotropic that is, with principal properties in orthogonal directions or transversely isotropic with isotropic properties in the transverse plane with the laminate then exhibiting anisotropic with variable direction of principal properties , orthotropic, or quasi isotropic properties. Quasi isotropic laminates exhibit isotropic that is, independent of direction inplane response but are not restricted to isotropic out of plane bending response. Depending upon the stacking sequence of the individual layers, the laminate may exhibit coupling between inplane and out of plane response. An example of bending stretching coupling is the presence of curvature developing as a result of inplane loading. See also Laminate Material stub Category Composite materials ... more details
Calcific bursitis refers to calcium deposits within the bursae . This most occurs in the shoulder area. The most common bursa for calcific bursitis to occur is the subacromial bursa . A bursa is a small, fluid filled sac that reduces fricton, and facilitates movements between its adjacent tissues ie, between tendon and bone, two muscles or skin and bone . Inflammation of the bursae are called bursitis . Causes Calcific bursitis may be related to Calcific tendinitis . Sometimes calcium deposites of the involved tendons penetrate into the bursae. Chronic bursitis. Lack of bursitis treatment, or repetitive bursitis may lead to calcific bursitis. Signs and symptoms Pain during rest Tenderness on palpation Joint stiffness Stiffness reducing joint range of motion Swelling medical Swelling Diagnosis X ray MRI scan Treatment Ice in the acute stage Rest immobilization of the affected limb in the acute phase Non steroidal anti inflammatory drugs Injections of steroid Physical therapy Surgical treatment See also Bursitis Calcific tendinitis References Darlene Hertling and Randolph M.Kessler. Management of Common Musculoskeletal Disorders . Third Edition. ISBN 0 397 55150 9 http www.medicinenet.com calcific bursitis article.htm Calcific bursitis at MedicineNet Category Soft tissue disorders Category Bursae Soft tissue disorders fa ... more details
Wave velocity is a wave property, which may refer to phase velocity , the velocity at which a wave phase propagates at a certain frequency pulse wave velocity , the velocity at which a pulse travels through a medium, usually applied to arteries as a measure of arterial stiffness group velocity , the propagation velocity for the envelope of wave groups and often of wave energy, different from the phase velocity for dispersive waves signal velocity or information velocity , which is the velocity at which a wave carries information front velocity , the velocity at which the first rise of a pulse above zero moves forward disambig ar zh ... more details
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