Three-point bending mode

Pre-cracked specimens were tested in three point bending (mode I) at room temperature and at Vo =1 m/s using a falling weight type machine Fractovis 6789 by Ceast. 

A test may typically involve the extraction of force P and energy associated with the initiation of crack extension from an instrumented impact load-deflection trace (see Fig. 7) for a test conducted in three-point bending mode (Charpy arrangement). The associated fracture stress can be calculated from... 

Figure 11 Dynamic load thermomechanical analysis of a carbon fibre/epoxy resin beam measured in three point bending mode. The force steps between 0.5 and 1.5 N and hack every 12 s. Heating rate 5°C min in air...

One of the more important of the practical tests is the heat distortion temperature (HDT). The HDT is defined as the temperature at which a 100 mm length, 3 mm thick specimen bar at 1.82 MPa in a three-point bending mode deflects 0.25 mm. Young s modulus at the HDT is 0.75 Gpa (133,134). For unfllled polymers, both the Vicat and the HDT tests usually record a temperature just above the glass transition temperature, or for melting conditions, just below the temperature of flnal disappearance of crystallinity. For polymer blends, both the Vicat and the HDT will tend to reflect the properties of the continuous phase. If the polymer contains filler which raises the modulus, the HDT will be somewhat increased. 

Figure 4.40. Effect of crystaUinity on the deflection of glass-fllled poly(phenylene sulfide) under an 1820kPa load with increasing temperature TMA three-point bending mode at 3°C/min in helium (Bair, unpubhshed, 1999).

High performance of autotension mode (coupled static/dynamic control) for film and three-point bending modes... 

As explained previously by Lu et al. [215], there are standard testing methods and equipment that can be employed for reinforced aerogel materiak such as polymer cross-linked ones (X-aerogek), although their standard mechanical characterization does not exist. Flexural tests are carried out in three-point bending mode, normally leading to failure imder tensile bending stresses in... 

A circular specimen of MgO is loaded using a O three-point bending mode. Compute the minimum... 

Moisture loss below freezable water range was mainly responsible, according to Vittadini et al. [145], for the thermomechanical behaviour of prebaked pizza dough reheated with a microwave oven as detected with DMA in three-point bending mode. Thermal transitions were associated to pizza texture characteristics thermograms presented two transitions a transition was detected at 60 40°C and was found responsible for the leathery texture in microwaved pizza, while the one detected at 0 30 °C was the dominating transition in the soft pizza reheated by conventional oven. 

Data were obtained using the three point bending mode of DMTA on 1-mm-thick slabs of lead-free alloys, together with hardness values recorded for joints. 

Flexural tests according to ASTM D790 were also performed. Rectangular samples wa-e cut from the original molded parts (52.8 x 12.7 x 2.5 mm) and left to relax for 3 weeks before testing. The flexural modulus of the stractural foams was evaluated via a univasal mechanical tester UNITED SFM-10 in the three point bending mode at a velocity of 1 mm/min. A minimum of 5 samples were measured for each condition. 

The flexural moduli of the compression-molded eco-composite coupons were determined using a TA Instruments Q800 Dynamieal Meehanical Analyzer (DMA) in three-point bending mode with strips cut from the coupois. The test method utilized a temperature ramp from room temperature to 200 °C and a frequency sweep from 0.1 to 100 Hz. A differential scanning calorimeter (DSC, TA Instruments QlOO) was used to eharacterize the thermal properties. 

Dynamic mechanical analysis (DMA) was carried out on a Perkin Elmer (DMA 7e) instrument in the three-point bending mode and storage modulus, loss modulus, tan delta of the samples were determined. The test was performed in the temperature sweep mode from 20 C 150°C under a helium atmosphere at a frequency of IHz and at a heating rate of 5 C/min. Two samples were tested for each formulation. 

---