Crosshead speed

The yield strengths of the polymers A, B and E from flexural tests are plotted in Fig. 6.5 against the strain rate on a logarithmic scale. The crosshead speed was... 

Texture measurements Texture of canned carrots was measured using Instron Universal Testing Machine (Model 1011) fitted with Kramer shear cell. Thirty grams of drained carrot cubes were evenly placed in the Kramer shear cell and were compressed, sheared and extruded using a crosshead speed of 100 mm/min. Each measurement was repeated 10 times and the mean was used to express the firmness of carrot cubes in Newton(N). 

The cement shows marked viscoelastic properties. Thus, measured strength is affected by the crosshead speed of the testing machine and this... 

When the load has reached a critical plateau value, the crack continues to propagate at constant load. Crack propagation can be stopped by removing the load, with the implication that several readings can be made on one test specimen. Crack velocity is determined by the crosshead speed, modulus of the material and specimen dimensions. 

Figure 1. Stress-strain curves of polycarbonate-polydimethyl-siloxane block copolymers (Crosshead Speeds 5 cm/min). (Reproduced from Refs. 15 18. Copyright 1980, 1984 American Chemical Society.)...

In Equations 2 and 3, Ei and Ef are strains at point I in the initial and final collection rate areas, Is is the starting point and Ir is the rate transition point, Ti and Tf are the initial and final collection rates in sec/point, C is the crosshead speed in lnches/sec, and L is the sample length in inches. 

Crosshead Speed 2.000in/min Full Scale Load 20.lbs... 

Stress-Strain Data. Tensile tests were made with an Instron tester at some seven crosshead speeds from 0.02 to 20 inches per minute at five or six temperatures from 30° to —46°C. The tests were made on rings cut with a special rotary cutter from the circular sheets of the elastomers. The dimensions of each ring were determined from the weights of the ring and the disc from its center, the thickness of the ring, accurately measured, and the density of the rubber. Typically, the outside and inside diameters were 1.45 and 1.25 inches, respectively, and the thickness was about 0.085 inch. The test procedure used is described elsewhere (11), and the cubic equation, eq 4 in ref. j 2, was used to compute the average strain in a ring from the crosshead displacement. 

Stress-Strain Data. Figure 1 shows the tensile data obtained on the LHT-240 elastomer at 30°C and at seven crosshead speeds from 0.02 to 20 inches per minute. The nominal or engineering stress a is plotted against... 

Tensile and tear strengths were determined using ASTM standards D412 and D1004, respectively, at a crosshead speed of 0.42 mm/s (1 In/mln) values reported are the average for 3 specimens. The elastic and Inelastic (plastic) components of the total elongation... 

The tensile strength, modulus, and elongation at break were measured on an Instron Tensile Tester at a crosshead speed of 20 in./min (ASTM D-412) and the hardness by means of a Shore A Durometer (ASTM D-2240). 

Mechanical Properties. Mechanical properties obtained on the cured resins included tensile strength and fracture toughness. Tensile tests were run on an Instron model 1122 Universal Tester with a crosshead speed of 0.02 /minute. Tests were run on dry and saturated samples in air. Fracture toughness (K ) values have been obtained using a MTS 610 Materials Testing System at 0.02 /minute at ambient and elevated temperatures in air. The compact tensile specimens tested were 0.5 x 0.5 x 0.125 in dimension. Mechanical properties data are based on the results from four or more tests run at each condition. 

Stress-strain measurements were carried out on molded films ( 1 mm thickness) at room temperature by the use of microdumbell-shaped samples and an Instron tensile tester (model No. 1130, crosshead speed of 5 cm/min). The samples were premolded between Mylar sheets for 10 min at 162 °C at about 5000 psi, then remolded at 165 °C and 7000 psi for 20 min, and slowly cooled ( 1 °C/min) to 50 °C. Select samples were solvent extracted by MEK using a Soxhlet extractor before molding. 

Swelling tests and determination of tensile properties. The procedure for estimating cross-link density from equilibrium swelling data is described in detail in a previous paper (6). The tensile properties of the PU films were carried out at 23°C and 60% relative humidity. The crosshead speed and distance were 10 mm/min and 30 mm, respectively. A more detailed description of the tensile tests is given elsewhere (6). 

Fig. 4. Variation of K,c with crosshead speed, y, for a DGEBA epoxy polymer cured with different stated phr of TETA and tested at 20 °C 1,1 Brittle stable (type C) propagation O Kfa,...

Fig. 5. Variation of Kk with temperature for the same epoxy polymer as in Fig. 4. The symbols have the same meaning and a crosshead speed of 0.5 mm/min was used 9>...

Tensile moduli were measured from standard dog-bone samples (2.0 mm thickness, 4.7 mm width, and 22.0 mm gauge length) in a Model 1122 Instron. Flexural modulus was determined using a testing apparatus which consists of two aluminium/steel pieces attached to the Instron which is fitted with a tensile load cell. This device effectively performs an inverted three-point bend the two side bars remain stationary above the sample as the central bar below the sample moves upward. Flexural samples measured ca. 52.0 x 1.7 x 13.1 mm and were tested using a 25.4 mm span (distance between the two side bars). Crosshead speed (CHS) for both flexural and tensile testing was 1.0 mm/min. 

For a TPA measurement, make sure that the degree of compression, plunger size, and crosshead speed are the same among tests that are to be compared. Adjust the operating characteristics of the machine when testing other types of samples. For example, if the samples are harder than those used in these protocols, reduce the degree of compression and/or the cross-head speed. 

Mechanical tests were carried out with an Instron 1123 mechanical test machine operated at a crosshead speed of 2 mm/min. Moduli were determined using rectangular bar specimens that were pulled in tension using an extensometer to obtain accurate strain measurements. Initial slopes of the stress-strain curves represent the moduli. Strength measurements were made using ASTM Type V tensile bars (cut after the composites were produced) that were pulled in tension, and the maximum tensile stresses attained were taken as the strength values. 

Fig. 5.17 Unconfined compression stress-strain curves and experimentally measured temperature increase ATa as a function of strain for PS (Dow 685), LDPE (Dow 640), and PP (LG H670). The initial test specimen was at 26°C and the crosshead speed of the compressing har with the load cell was 25.4 mm/min. The specimen dimensions were 101 mm diameter and 71 mm height. [Reprinted by permission from M. H. Kim, Ph.D Thesis, Department of Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ (1999).]...

---