Compression force deflection

Combined liquid crystalline polymers, 49 Combustion testing, 245 Composites, thermoplastic, 32 Compression force deflection (CPD), 244 Compression tests, 242 Condensation... 

CFD compression force deflection, CS compression set, % Ct compression set expressed as a percentage of original thickness... 

Indentation force deflection (HD) Compression force deflection (CFD) Compression set... 

Two techniques allow determination of the compressibility of foam. The methods are related and the application dictates which method better defines the quality of the product. For example, for furniture cushions, indentation force deflection (IFD) is a more common test technique than compression force deflection. Both methods determine the amount of force required to compress a foam to a percentage of its thickness. In the IFD test, the plunger that compresses the foam is smaller than the foam sample. This presumably correlates to a person sitting in the center of a chair cushion. 

Representative test methods of flexible foam properties, as defined by the ASTM D-3574 are density, IFD (indentation force deflection), CFD (compression force deflection), sag factor, compression set, tensile and tear strengths, elongation, resilience, dry-heat aging and steam autoclave aging. 

Other important properties of flexible urethane foams include indentation force deflection (IFD) or compression force deflection (CFD), compression set, and humid agiiig. 

The CFD (compression force deflection) as well as IFD (indentation force deflection) curves of these foams are relatively linear in comparison with slabstock foams, as shown in Figures 10 and 11. 

Compression Force Deflection Test ASTM D 3574 - Test C. This test consists in measuring the force necessary to produce a 50% compression over the entire top area of a flexible foam specimen. The... 

The compression force deflection test consists of measuring the load necessary to produce a 50 percent compression over the entire top area of the foam specimen. This test differs from the IFD test described previously in that the flat compression foot used in the test is larger than the specimen. The compression foot is brought into contact with the specimen. The specimen is compressed 50 percent of its original thickness and after 1 min the final load is observed. The compression force deflection is recorded as the load required for a 50 percent compression of specimen area. 

Method D, the dynamic fatigue test for carpet cushion, was developed to evaluate the specimen by repeatedly deflecting the carpet cushion by a rubber-covered roller exerting a specified force on the test specimens. The test determines the retention of force support at 65% compression force deflection (CFD), loss of thickness, and structural breakdown as determined by visual inspection. 

Fig. 11 Force-deflection profiles of soft gelatin capsules containing polyethylene glycol as a fill liquid and coated with Eudragit L 30 D-55 obtained from compression testing (A) polymer plasticized with 20% triethyl citrate (B) polymer plasticized with 20% tributyl citrate. (From Ref. l)...

Indentation-Force Deflection (See also Compression/Deflection Properties)... 

Covers density, indentation-force deflection, compressionforce deflection, constant deflection, compression set, tension, tear resistance, air-flow, resilience (ball rebound), static-force loss at constant deflection, dynamic fatigue, steam autoclave aging, and dry-heat aging. 

CuiO-treated flexible polyurethane foam were not significantly different from the comparable untreated flexible polyurethane foam. The physical properties examined were tensile strength, elongation, tear strength, resilience, indentation force deflection, support factor, compression sets, and airflow. 

Melvin et al. [1988] analyzed frontal biomechanics of the chest. The dynamic compliance is related to viscous, inertial, and elastic properties of the body. There is an initial rise in force, which is related to the inertia of the sternal mass, which is rapidly accelerated to the impact speed This is followed by a plateau in force, which is related to the viscous properties and is rate dependent. There is also an elastic stiffness component from chest compression that adds to the force. The force-deflection response can be modeled as an initial stiffness k = 0.26 + 0.60(17" — 1.3) and a plateau force T = 1.0 -F 0.75( V — 3.7), where k is in kN/cm, F is in kN, and the velocity of impact V" is in m/sec. The force P reasonably approximates the plateau level for lateral chest and abdominal impact, but the initial stiffness is lower at f = 0.12(17— 1.2) for side loading [Melvin and Weber, 1988). 

Figure C.3 shows half of a strut (a beam loaded axially in compression) of length L. Its ends are built-in to the rest of the moulding. Consequently, they cannot rotate or move sideways when the compressive forces F are applied. If the strut were to bend, so that the lateral deflection was i at a point P, the bending moment at P would be...

Deflection of the Resin 2 cone as a function of axial compressive force. Calculated stiffnesses are noted. 

FTC measurements were conducted 90 seconds after demoulding. The foam pad was removed from the mould, weighed and placed in the FTC apparatus (Instron 4502). The force detection device is equipped with a 5.0 kN capacity pressure transducer. The actual force is shown on a digital display. This device mimics the ASTM D3574, Indentation Force Deflection Test and provides a numerical value of freshly demoulded foams initial hardness or softness. The pad was compressed to 70 percent of its original thickness at a cross head velocity of 380 mm per minute with the force necessary to achieve the highest compression cycle recorded in Newtons. Values are reported as the FTC value for the foam based on the assumption that the lower the FTC values the better the dimensional stability of the foam. 

The data on the mechanical properties of PTL materials are sparse. Mathias et al. reported on the compressive deflection as a function of compressive force for carbon fiber paper and carbon cloth materials (no specifications on material composition or manufacturer were provided) (Mathias et al., 2003). The maximum applied load was 2.75 MPa and the maximum compressive strain was approximately 23% and 53% for the fiber paper and cloth samples, respectively. Significant but decreasing hysteresis was observed on both materials after 10 cycles (from zero to maximum load). 

Measuring the mcreasing force for a given deformation by an external load with the measurement setup described in Haus et al. (2013) leads to the force-deflection graph shown in Fig. 8. As the strain corresponds to flie planned actuating state, the uniaxial compressive modulus can be interpolated using the area of the probe head and the height of the actuator. The calculated modulus for the characterized DE is 210 kPa. 

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