Impact failure

It may be seen from Fig. 2.80 that some plastics experience the change from ductile to brittle behaviour over a relatively narrow temperature range. This permits a tough/brittle transition temperature to be quoted. In other plastics this transition is much more gradual so that it is not possible to attribute it to a single value of temperature. In these circumstances it is common to quote a Brittleness Temperature, rg(l/4). This temperature is defined as the value at which the impact strength of the material with a sharp notch (1/4 mm tip radius) equals 10 kJ/m. This temperature, when quoted, gives an indication of the temperature above which there should be no problems with impact failures. It does not mean that the material should never be used below Tb(1/4) because by definition it refers only to the sharp notch case. When the material has a blunt notch or is un-notched its behaviour may still be satisfactory well below Tb(1/4). 

The Uansportation industry is subject to more impact failures of vessels that lead to Bleves. The Bleve occurs simultaneously with the impact in most recorded cases, but not all. Sometimes there is a delay due to lack of total penetration of the vessel with a hole or crack, and time is needed for the temperature in the container to rise. Failures of the vessel can lead to fireballs of more than several hundred feet in diameter. 

Accidents may be caused by impact, failure of container or pipeline, or during loading/unloading. The hazards arise from ... 

Roberts makes clear that P is intended to be the vapor pressure when the failure occurs. In a BLEVE, this might be the relief valve setting Pq, whereas in a fireball resulting from an impact failure, it will be the vapor pressure at ambient temperature, as is used in FLARE (described in Appendix C). For a fireball following a release of gas (as opposed to liquefied gas), P should be the storage pressure. 

Although some polymers may be satisfactory when used under the stress of static loads, they may fail when subjected to impact. The impact resistance, or resistance to brittle fracture, is a function of the molecular weight of a polymer. Thus uhmwpe is much more resistant to impact failure than general purpose high-density polyethylene (hdpe). The impact resistance of brittle polymers is also increased by the addition of plasticizers. Thus polyvinyl chloride (PVC), plasticized by relatively large amounts of dioctyl phthalate, is much less brittle than unplasticized rigid PVC. 

C Repeat observations—direct product impact Failure to meet warning letter commitments Consent decree >100... 

Polymer Engineering and Science 38, No.l, Jan.1998, p.194-203 RELATIONSHIP BETWEEN STRAIN RATE, TEMPERATURE, AND IMPACT FAILURE MECHANISM FOR POLY(VINYL CHLORIDE) AND POLY (ETHYLENE TEREPHTHALATE) Green J L Petty C A Gillis P P Grulke E A Michigan,University Kentucky,University... 

Impact Failure. Standard notched Izod impact measurements have been made over wide temperature ranges on specimens cut from compression molded %-inch thick sheets of BPA polycarbonate and two BPA carbonate-silicone block polymers (Figure 4) (see Table I for compositions and properties). In the homopolymer a ductile-brittle transition occurs at 0° to —15°C, as reported previously (4, 5). Introduction of 15 and 25% silicone lowers the transition to —45° and —110°C (block polymers A and B). As indicated in Table I, this increase in toughness at low temperature is accompanied by the reduction of modulus and yield stress. 

Impact failure, sandwich structures, intra-layer crack, inter-layer crack, finite elements and cohesive elements. 

D Modelling of Impact Failure in Sandwich Structures notice that the crack speed along the lower interface reaches the Rayleigh wave speed soon... 

Stationary failure modes Impact failure modes... 

Among high-temperature batteries, the lithium-iron sulfide systems are reasonably safe, although there are some hazards connected with the 450-500°C operating temperature. The sodium-sulfur-system impact failure hazards are primarily connected with the possibility of SO2 emissions, sodium oxide dust, and fires resulting from sodium exposure to moisture. 

The waste PP/GRT blends were prepared using a Haake internal mixer at a temperature of 180 C and a rotor speed of 30 rpm for 8 min (Egodage et al., 2009). Blends of nine different compositions with GRT concentrations up to 70 wt.% were prepared. Mixing torque was increased with an increase in the GRT content. The tensile strength, modulus, and tear resistance decreased with the GRT content, while the elongation at break and the impact failure energy increased. 

The upper hard layer impact failure is cause of water cell break or water hazard. 

Figure 8.81 Impact failure origin in glaze coating from a space shuttle tile scanning electron micrograph. (Reproduced courtesy of The American Ceramic Society, Westerville, OH.)...

Table 4.14 Impact failure energies from instrumented free-falling weight tests for thermoplastic films ...

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