Planes of Weakness

The resulting mouldings and extrudates are consequently anisotropic and mouldings can be four to five times as strong in one direction as in another direction. This can lead to planes of weakness and easy fracture when subject to shock (impact) stresses. Generally such orientation is undesirable but there are at least two instances of its being of value ... 

Accdg to MIL-STD-331 (Ref 43) where this test is described in detail as Test No 101, in that part of the test where the fuzes are positioned with the longitudinal axis in a horizontal direction, the fuzes are oriented so as to expose what is considered to be the most vulnerable plane of weakness In general, it is not required that the fuzes be operable after this test, but the samples judged to have withstood this test are those in which (1) no elements shall explode and (2) no parts shall be broken, be deformed, be displaced, come apart, or 1 arm in such a manner as to make the assembly unsafe to handle or dangerous to use. 

Schreiber and co-workers have noted very persistent history effects in linear polyethylenes (69). Fractions which have been crystallized from dilute solution required times of the order of hours in the melt state at 190° C in order to attain a constant die swell behavior upon subsequent extrusion. The viscosity on the other hand reached its ultimate value almost immediately. The authors concluded from this result that different types of molecular interactions were responsible for elastic and viscous response. However, other less specific explanations might also suffice, since apparent viscosity might be relatively intensitive to the presence of incompletely healed domain surfaces, while die swell, requiring a coordinated motion of the entire extrudate, might be affected by planes of weakness. It would... 

Dr. Gluskoter. What is the evidence for a syngenetic origin for the uranium minerals in the Swiss anthracite Why could this not be secondary deposition along planes of weakness (bedding) ... 

Cannel coal Nonbanded coal in which the liptinite is predominantly sporinite. Fusain coal layers composed of chips and other fragments in which the original form of plant tissue structure is preserved commonly has fibrous texture with a very dull luster friable and resembles charcoal commonly concentrated in bedding layers or lenses that form planes of weakness in coal and thus is often exposed on bedding surfaces of broken coal. 

Slickensides are easily observable shiny planes of weakness along which movement occurs in shrink-swell medium-to-heavy clay soils. These are shearing faults, which exist permanently in wet or dry expansive clays. They take the form of cracked, polished, or grooved surfaces, ranging from 10 mm to 200 mm across. Slickensides often run through the soil mass in many directions and may break the structure up into bowl-shaped blocks. They can move up to 25 mm per year. Hence, the frequency and size of slickensides present can quantify the potential capacity of the soil to shrink and swell (i.e., develop cracks when dry). Soils or soil layers with slickensides are highly impermeable to water movement, especially when they are moist and root growth is restricted. 

Fracture Fracture describes the way a substance breaks when it neither cleaves nor parts (breaks along plane of weakness). The most common kind of visible fracture is conchoidal, which produces curved, smooth surfaces (glass, quartz). Freshwater pearl one that occurs in a freshwater (non-marine) mollusk. Gem a general term used to describe precious and semi-precious stones, usually after they have been cut and polished. In archaeology, it refers only to engraved stones (cameo, intaglio, seals, etc.). 

Some minerals, when struck with force, will cleanly break parallel to planes of weakness in their atomic structure. This breakage is called cleavage. Muscovite... 

The pellet lengths were limited by the position of the breaker plate installed on the interior surface of the cover of the die. However, the centrifugal force from the rotating die and impacts from loose pellets within the shell cover of the die, cause the pellets to break off at random lengths. Also, included pieces of plastics and textiles form planes of weakness and the pellets break shorter. 

FRACTURING Intrusion of grout fingers, sheets and lenses along joints, planes of weakness, or between the strata of a formation at sufficient pressure to cause the strata to move away from the grout. 

Hydration along crystallographic planes of weakness and the release or exchange of ions (Petit et al., 1987 Schott and Petit, 1987). 

Delamination leading to spall of cover Horizontal corrosion induced cracks Due to plane of weakness at rebar level... 

Both hardwoods and softwoods have cells (usually grouped into structures or tissues) that are oriented horizontally in the radial direction and which are called rays. The rays, composed of parenchyma with lignifled cell walls or sclerenchyma, connect various layers from pith to bark for storage and transfer of food. In softwoods, rays are one-cell thick. In hardwoods, they vary in size from one-cell wide and a few cells high to more than 15-cell wide and several centimeters high. Rays represent planes of weakness along which drying checks develop easily. 

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