Cross bend testing

Cross-bend Test. (1) Term sometimes used for transverse strength test (q.v.). 

Testing of Painted Products. The enhancement of paint adhesion is one of the principal functions of conversion coating (20—22). A group of tests based on product deformation is used to test the painted product. The appHance and cod-coating industries use the mandrel bend, the cross-hatch adhesion test, and the direct and reverse impact tests. Adhesion after a water soak is judged using a cross-hatch test performed on the exposed surface. 

Figure 7, Temperature dependence of failure stresses in Instron three-point bend tests on Vs inch notched Izod bars cut from (a) extruded polycarbonate sheet and (b) compression molded block polymer B. Crosshead rate = 0,02 inch /min. Span = 2 inches, o = net section stress = force/net cross-section at notch root, O, Craze initiation , ductile failure X, brittle failure ...

Another important large deformation measurement is the three point bending test (Figure 17.19). Here a mold of the solid fat is plaeed on two beams and a third beam applies an external force between the other two beams. The Young s modulus ( ) and yield force may be determined depending on the cross-section as (rectangular Equation (17.18) or circular Equation (17.19)) ... 

In this paper the influence of the level of thermal residual stresses on the development of transverse cracking in cross-ply carbon-polyetherimide laminated beams subjected to bending has been considered. Different levels of ply-to-ply residual stresses were obtained by producing cross-ply ([90/0]s) laminates having different lay-ups in the 0° layer. Two methods were used to analyse the bend tests. The first considered the stress at the formation of the first transverse crack, the second the energy released at the formation of this crack. 

The crystal phases in the glass-ceramics were determined by XRD analysis. All instruments were precisely and identically set to ensure a high precision to obtain the integral peak area. The microstructure of the fresh fractured cross section of the glass-ceramics was observed by SEM. The thermal expansion coefficient (TEC) was calculated from room temperature to 500 °C at a heating rate of 5°C/min in the dilatometry analyser (NETZSCH, DIL402PC). The flexural strength was determined in a 3-point bend test at a constant strain ratio of 0.5mm/min. 

The composites were cut and ground into bars for three-point-bending test in an lnstron-5566 machine with a crosshead speed of 0.5mm/min and a span of 24mm. Both the polished cross section and fracture surface were observed by Electron Microprobe Analysis (EPMA JXA-8100, JEOL, Tokyo, Japan) equipped with EDS. 

Fig. 932 SEM showing SCC crack resulting from cross-link of pit, U-bend test, t, for an HAZ DSS in 40 wt.% CaCl2 solution [127],...

Four-point bend tests were performed at room temperature and at 1400°C. All bending tests had an upper span of 10 mm and a lower span of 30 mm. An Instron-type universal tester was used for bending tests, with a constant cross head of 0.2 mm/min. Figure 5.36 shows the dimensions and coordinate system of the beam specimen with ground surface in a four-point bend test. 

The flexural strength by means of three points bending testing is conducted according to ASTM D790-86 standard. Samples are eut to dimensions of 130 mm X 13 mm X 3 mm (length x width x thickness). The flexural test is earned out by using a Universal Test Machine (Model 5525, Instron Corporation, Norwood, Massaehusetts, USA) at a cross-head speed of 3.1 mm/min. The values obtained represented the mean of five specimen measurements. 

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