Knife resistance

The protection levels are categorised into knife resistance (KR) and spike protection (SP), with three protection levels for each (levels 1,2, and 3). The maximum penetration is measured with two energy levels, El and E2, with permissible penetrations of 7 mm and 20 mm, respectively. 

For spike protection, the material should also pass the knife resistance test and should not allow any penetration of the spike at energy level El. The spike protection level is investigated in addition to the knife resistance level. 

PSDB=Police Scientific Development Branch KR=knife resistance SP=spike protection. 

Bleetman A, Watson CH, Horsfall I, Champion SM. Wounding patterns and human performance in knife attacks optimising the protection provided by knife-resistant body armour. J Clin Forensic Med 2003 10(4) 243-8. 

Dyneema SB21/31/51 is for ballistic and knife resistant fabrics. 

Chain mail can also be used as a flexible knife-resistant armour. In this case the action of the chain links is to capture the blade tip after a small amount of perforation. It is therefore necessary to use either a very fine chain link diameter or a padding system. Typically the armour systems will consist of a layer of chain mail positioned on the front face of a conventional multilayer ballistic fabric pack. This construction has very good flexibility and provides both knife and ballistic protection at a weight comparable to, although slightly greater than, a laminated fabric solution. It is, however, typically mote flexible than the laminated fabric and has foimd particular use in female armour, which needs this greater flexibility to allow for breast shape. 

Kneaders Kneading Kneading mixers Knecht compound Knecht method Knife mills Knight and Allen Knives Knize Ten Knockdown Knockdown resistance... 

Martensitic stainless steels are usually used in the softened (tempered at or above 650°C) or in the fully hardened condition (tempered at or below 250°C) so that there is no substantial reduction in corrosion resistance resulting from carbide precipitation. However, the hard soldering of knife blades can result in carbide precipitation and pitting of the blade at the area adjacent to the handle, and care must be taken in the soldering process to avoid this danger. 

Psychosurgery. Nnmerous brain procednres, which can now be performed in a mnch less invasive manner via techniqnes snch as the gamma knife, can be beneficial for patients who are resistant to all other forms of treatment. 

Silvery-gray metal hexagonal crystal structure malleable, ductile, and soft enough to be cut with a knife density 8.223 g/cm melts at 1,359°C vaporizes at 3,221°C resistivity llhxlCH ohm-cm at 25°C Young s modulus 5.75xl0n dynes/cm2 (from velocity of sound measurements) shear modulus 2.28 dynes/cm2 Poisson s ratio 0.261 thermal neutron absorption cross section, 46 barns insoluble in water soluble in acids. 

De Man (1983) has reviewed this property of fats. Consistency is defined as (1) an ill-defined and subjectively assessable characteristic of a material that depends on the complex stress-flow relation or as (2) the property by which a material resists change of shape. Spreadabil-ity, a term used in relation to consistency, is the force required to spread the fat with a knife. The definition is similar to that for hardness the resistance of the surface of a body to deformation. The most widely used simple compression test in North America is the cone penetrometer method (AOCS Method Cc 16-60, 1960). More sophisticated rheological procedures are also available. Efforts have been made to calibrate instrumental tests with sensory response. With the cone penetrometer method, penetration depth is used as a measure of firmness. Hayakawa and De Man (1982) studied the hardness of fractions obtained by crystallization of milk fat. Hardness values obtained with a constant speed penetrometer reflected trends in their TG composition and solid fat content. 

The discovery of the shape memory effect in TiNi by Buehler et al. at the Naval Ordinance Labs occurred during an investigation of the alloy for possible use as a corrosion-resistant knife for underwater activities. The investigators called the alloy nitinol for Nickel, Titanium, and Naval Ordinance Labs. 

More recent uses have been for forming dies and jigs, weaving shuttles, knife handles, glass door pulls and railroad track connectors where electrical resistance is needed for automatic signaling systems. 

Corrosion resistance of aluminum alloys. Researchers have shown that aluminum alloys, both welded and unwelded, have good resistance to uninhibited HN03 (both red and white) up to 50°C. Above this temperature, most aluminum alloys exhibit knife-line attack (a very thin region of corrosion) adjacent to the welds. In inhibited fuming HNO3 containing at least 0.1% hydrofluoric acid (HF), no knife-line attack was observed for any commercial aluminum alloy or weldment even at 70°C (160°F). 

F. Place the mount, epoxy down, on a hard flat wood surface and drill through the mount boles and epoxy underneath. Enlarge the holes in the epoxy with a sharp pointed knife.The screws should slip through the holes in the mount without resistance. 

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