Center of pressure

The force exerted on a submerged planar surface of area A is given by F = p A where p is the pressure at the geometrical centroid of the surface. The center of pressure, the point of application of the net force, is always lower than the centroid. For details see, for example. Shames, where may also be found discussion of forces on curved surfaces, buoyancy, and stability of floating bodies. 

Balance. If the center of mass of the projectile is not located extremely close to its longitudinal centerline, the center of pressure can form a couple with the inertial reaction through the center of mass, making the projectile tend to tumble in the barrel (Barker, 1985). Tumbling is prevented by the gun barrel, which exerts counteracting asymmetric forces on the projectile during its acceleration. These forces can lead to asymmetric wear of the projectile. If the center of mass is closer to one end of the projectile, which it nearly always is, the situation is unstable the wear increases the imbalance, which increases... 

A fin-stabilized projectile must have its center of mass well forward of its center of pressure. This means that the point thru which gravity can be said to act must be well in advance of the point at which the aerodynamic forces act. A good example of this is a metal dart which has a brass body of considerable density and fins placed on a lightweight wooden boom well to the rear... 

Center of Pressure. In a conventionally shaped bullet forces tending to retard the bullet in flight are focussed on a point along the axis of the bullet towards the nose. This point is the center of pressure... 

Overturn Couple or Lever Arm. The distance between the center of gravity and the center of pressure is known as the overturning couple or the lever arm, and thru this the stabilizing forces deriving from spin operate. Since neither of these two centers lies exactly on the axis (due to normal manufg errors) the result is yaw. The... 

Assume that the centers of pressure are uniformly distributed along the z-axis from z = 0 to z = —oo. The stresses in an infinite solid medium can be obtained by integration from... 

The 3-D ground reaction force vector, the vertical ground reaction torque and the point of application of the ground reaction force vector (i.e., center of pressure) are measured with force platforms embedded in the walkway. Force plates with typical measurement surface dimensions of 0.5 x 0.5 m are comprised of several strain gauges or piezoelectric sensor arrays rigidly mounted together. 

Ruhe, A., Fejer, R., and Walker, B. 2011. Center of pressure excursion as a measure of balance performance in patients with non-specific low back pain compared to healthy controls A systematic review of the literature. Eur Spine J. 20 358. 

Another variable that must be considered is die location of the external force acting on the system. For the case of a subject stepping on a force platform, the location of the applied load is assumed to act at the center of pressure (COP). The term is aptly named, since the subject really applies a... 

Static Stability. An aircraft is statically stable if a small perturbation in its attitude causes a restoring aerodynamic moment that erases the perturbation. Typically, the aircraft center of gravity must be ahead of the center of pressure for longitudinal stability. The tails or canards help provide stability about the different axes. Rocket engines are said to be stable if the rate of generation of gases in the combustion chamber does not depend on pressure stronger than by a direct proportionality, such as a pressure exponent of 1. 

The influence of operating parameters (W, U, and G) on performance parameters was studied for eiastohydrodynamic lubricated conjunctions with Idealized conditions of no side leakage, fully flooded conditions, isothermal behavior, smooth surfaces, and assuming a Newtonian fluid condition. Twenty-two cases were investigated covering a complete range of operating parameters normally experienced in eiastohydrodynamic lubrication conjunctions. From these studies simple formulas were developed for the amplitude, width and location of the pressure spike, the center of pressure, minimum film thickness and the mass flow rate. 

The present paper will use the very fast and accurate method of calculating the pressure and film thickness in eiastohydrodynamic lubricated conjunctions developed by Houpert and Hamrock (1986) and investigate the effects of a complete operating range of load, speed and materials parameters. The performance parameters to be studied are the details of the pressure spike including the amplitude, width and location of the spike, the mass flow rate, the center of pressure the minimum film thickness. Formulas will be developed to describe the performance parameters as a function of the operating parameters. The results to be presented are only applicable for idealized situations of smooth surfaces, Newtonian fluid behavior, isothermal and fully flooded lubrication conditions. 

A calculation very useful in rolling traction studies is the location of the center of pressure. The appropriate equation is... 

Table 2 shows the effect of the operating parameters on the location of center of pressure as obtained from the numerical analysis. A least squares fit to this data provided for the formulation of the following equation... 

The values obtained from this expression are shown in the last column of Table 2. In all cases shown in Table 2 the center of pressure is in front of the center of the Hertzian contact. 

While the applied pressure causes an overall shrinkage of the molecular epoxy structure, it also activates motion of the water molecules. Since the shapes and sizes of the water-occupied micropores vary statistically, as do the configurations of the overall polymeric framework and the microtube structures, the applied isotropic external stress could well translate into many inhomogeneous centers of pressure of disparate amplitudes acting on highly anisotropic neighborhoods on the microlevel. 

The localized centers of pressure would therefore squeeze water molecules along preferred directions into yet unoccupied and inaccessible portions of the free volume. 

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