Compression load deflection

Figur6 12 Measurement of (a) indentation load deflection (ILD) and (b) compression load deflection (CLD).

Warp-knitted spacer textiles with zones of different compression load deflection are patented. The patent was originally designed for the production of seat cushions and mattresses and mats (Muller and Miiller, 2007). 

Limiting instantaneous live load deflections is important to ensure that deck expansion joints are not damaged. Steel reinforced elastomeric bearings exhibit nonlinear compressive load-deflection behavior. Compressive stiffness of an elastomeric layer substantially increases with increasing shape factor. The total compressive deformation of an elastomeric bearing is equal to the sum of the compressive deformation of all its constituent elastomeric layers. 

The steam autoclave test consists of exposing the foam specimens to a low-pressure steam autoclave at a prescribed temperature and time, and observing the changes in the physical properties of the specimen. The test specimens are exposed to steam following specified preconditioning. After the exposure period, specimens are properly dried in a dryair oven. The compression load deflection is obtained before and after exposure and percent change from original value is reported. The steam autoclave compression set value is also calculated. 

Figure 3 Compression Load Deflection of Bulb, First Pull...

Compressive Behavior. The most kiformative data ki characterising the compressive behavior of a flexible foam are derived from the entire load-deflection curve of 0—75% deflection and its return to 0% deflection at the speed experienced ki the anticipated appHcation. Various methods have been reported (3,161,169—172) for relating the properties of flexible foams to desked behavior ki comfort cushioning. Other methods to characterize package cushioning have been reported. The most important variables affecting compressive behavior are polymer composition, density, and cell stmcture and size. 

A plate buckles when the in-plane compressive load gets so large that the originally flat equilibrium state is no longer stable, and the plate deflects into a nonflat (wavy) configuration. The load at which the departure from the flat state takes place is called the buckling load. The flat equilibrium state has only in-plane forces and undergoes only ex-... 

Compression set and durometer hardness are also important mechanical properties. Compression set is defined as the amount by which an elastomer fails to return to its original thickness after being subjected to a standard compressive load or deflection for a specified time at a specified temperature. A low percent compression set typifies a more compression resistant elastomeric formulation. Compression set of a closure on a sealed vial is a factor in maintaining the sterility and potency of the drug itself. 

The Vicat softening temperature is the temperature at which a standard deflection occurs for defined test samples subjected to a given linear temperature increase and a compression loading from a defined indenter of a specified weight. The load used is often ION (Vicat A) or SON (Vicat B) and must be indicated with the results. In either case the polymer cannot be used under this compression load at this temperature. 

In some variable-area flowmeters, gravity has been replaced by spring loading. In these units, an increase in flow results in a compression or deflection of a spring, and this motion is used as an indication of flow. These units can be mounted in any position, including horizontally, as flow-through pipeline devices. 

Compression Load Perpendicular to Rise PSI At Yield Point At 10 S Deflection Compression Modulus PSI Flexural Strength PSI Flexural Modulus PSI Shear Strength PSI Shear Modulus PSI... 

The same phenomenon occurs in the deflection of a column imder a compression loading. In this type of failure, a critical load is reached beyond which collapse occurs as a result of a rapid increase in the stresses beyond the yield point of the material. The critical pressure that causes collapse is not a simple function of the induced stress, as with tensile loads. In fact, it is directly proportional to the modulus of elasticity of the material and the moment of inertia of the shell and is inversely related to the cube of the radius of the curvature. 

Quasi-static and dynamic tests were conducted at the DLR Institute of Stmctores and Design, Stuttgart. The quasi-static test was conducted in a Zwick 1494 servo-hydraulic uniaxial loading frame (max. loads 500 kN, max. crosshead displacement 850 mm) with the stmcture test setup as shown in Figure 10.14(a). Vertical compression loads were applied by the test machine crosshead via a load cell to the test stmcture through the I-beam and measured at the load cell and on the load platform. The test was performed initially at a crosshead velocity of 5 mm/min for the first 20 mm of crosshead displacement, then increased and maintained at 20 mm/min until final collapse at 62 mm crosshead displacement. From the measured load-deflection curve the absorbed energy at failure can be calculated, which was measured to be 6.3 kJ at 62 mm displacement. This energy represents... 

Assuming that the compressive load was always uniformly distributed over the cross section, the midheight lateral second-order deflection due to load eccentricity,... 

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