strain

strain¹

—strainingly, adv. —strainless, adj. —strainlessly, adv.

/strayn/, v.t.

1. to draw tight or taut, esp. to the utmost tension; stretch to the full: to strain a rope.

2. to exert to the utmost: to strain one's ears to catch a sound.

3. to impair, injure, or weaken (a muscle, tendon, etc.) by stretching or overexertion.

4. to cause mechanical deformation in (a body or structure) as the result of stress.

5. to stretch beyond the proper point or limit: to strain the meaning of a word.

6. to make excessive demands upon: to strain one's luck; to strain one's resources.

7. to pour (liquid containing solid matter) through a filter, sieve, or the like in order to hold back the denser solid constituents: to strain gravy.

8. to draw off (clear or pure liquid) by means of a filter or sieve: to strain the water from spinach; to strain broth.

9. to hold back (solid particles) from liquid matter by means of a filter or sieve: to strain seeds from orange juice; to strain rice.

10. to clasp tightly in the arms, the hand, etc.: The mother strained her child close to her breast.

11. Obs. to constrain, as to a course of action.

v.i.

12. to pull forcibly: a dog straining at a leash.

13. to stretch one's muscles, nerves, etc., to the utmost.

14. to make violent physical efforts; strive hard.

15. to resist forcefully; balk: to strain at accepting an unpleasant fact.

16. to be subjected to tension or stress; suffer strain.

17. to filter, percolate, or ooze.

18. to trickle or flow: Sap strained from the bark.

n.

19. any force or pressure tending to alter shape, cause a fracture, etc.

20. strong muscular or physical effort.

21. great or excessive effort or striving after some goal, object, or effect.

22. an injury to a muscle, tendon, etc., due to excessive tension or use; sprain.

23. Mech., Physics. deformation of a body or structure as a result of an applied force.

24. condition of being strained or stretched.

25. a task, goal, or effect accomplished only with great effort: Housecleaning is a real strain.

26. severe, trying, or fatiguing pressure or exertion; taxing onus: the strain of hard work.

27. a severe demand on or test of resources, feelings, a person, etc.: a strain on one's hospitality.

28. a flow or burst of language, eloquence, etc.: the lofty strain of Cicero.

29. Often, strains. a passage of melody, music, or songs as rendered or heard: the strains of the nightingale.

30. Music. a section of a piece of music, more or less complete in itself.

31. a passage or piece of poetry.

32. the tone, style, or spirit of an utterance, writing, etc.: a humorous strain.

33. a particular degree, height, or pitch attained: a strain of courageous enthusiasm.

[1250-1300; ME streinen (v.) < OF estrein-, s. of estreindre to press tightly, grip < L stringere to bind, tie, draw tight. See STRINGENT]

Syn. 1. tighten. 3. STRAIN, SPRAIN imply a wrenching, twisting, and stretching of muscles and tendons. To STRAIN is to stretch tightly, make taut, wrench, tear, cause injury to, by long-continued or sudden and too violent effort or movement: to strain one's heart by overexertion, one's eyes by reading small print. To SPRAIN is to strain excessively (but without dislocation) by a sudden twist or wrench, the tendons and muscles connected with a joint, esp. those of the ankle or wrist: to sprain an ankle. 7. filter, sieve. 10. hug, embrace, press. 17. seep. 20. exertion. 22. wrench.

strain²

/strayn/, n.

1. the body of descendants of a common ancestor, as a family or stock.

2. any of the different lines of ancestry united in a family or an individual.

3. a group of plants distinguished from other plants of the variety to which it belongs by some intrinsic quality, such as a tendency to yield heavily; race.

4. an artificial variety of a species of domestic animal or cultivated plant.

5. a variety, esp. of microorganisms.

6. ancestry or descent.

7. hereditary or natural character, tendency, or trait: a strain of insanity in a family.

8. a streak or trace.

9. a kind or sort.

10. Obs. procreation.

[bef. 950; ME strene, OE streon lineage, race, stock, tribe; akin to strienan to beget]

Syn. 7. streak, vein, predisposition.

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In the physical sciences and engineering, a number that describes the relative deformation of elastic, plastic, and fluid materials under applied forces.

It arises throughout the material as the particles of the material are displaced from their usual position. Normal strain is caused by forces perpendicular to planes or cross sections of the material, such as in a volume that is under pressure on all sides. Shear strain is caused by forces that are parallel to, and lie in, planes or cross sections, such as in a short metal tube that is twisted about its longitudinal axis. See also deformation and flow.

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▪ mechanics

      in physical sciences and engineering, number that describes relative deformation or change in shape and size of elastic, plastic, and fluid materials under applied forces. The deformation, expressed by strain, arises throughout the material as the particles (molecules, atoms, ions) of which the material is composed are slightly displaced from their normal position.

      Strains may be divided into normal strains and shear strains on the basis of the forces that cause the deformation. A normal strain is caused by forces perpendicular to planes or cross-sectional areas of the material, such as in a volume that is under pressure on all sides or in a rod that is pulled or compressed lengthwise.

      A shear strain is caused by forces that are parallel to, and lie in, planes or cross-sectional areas, such as in a short metal tube that is twisted about its longitudinal axis.

      In deformation of volumes under pressure, the normal strain, expressed mathematically, is equal to the change in volume divided by the original volume. In the case of elongation, or lengthwise compression, the normal strain is equal to the change in length divided by the original length. In each case the quotient of the two quantities of the same dimension is itself a pure number without dimensions. In some applications, the change (decrease) in volume or in length for compression is taken to be negative, whereas the change (increase) for dilation or tension is designated as positive. Compressive strains, by this convention, are negative, and tensile strains are positive.

 In shear strain, right angles (90° angles) within the material become changed in size, as squares are deformed into diamond shapes the angles of which depart from 90°. Thus, in the illustration—> of the metal tube, the right angle CAF in the unstrained tube decreases to the acute angle BAF when the tube is twisted. The change in the right angle is, therefore, equal to angle BAC the tangent of which, by definition, is the ratio of BC divided by AC. This ratio is the shear strain, the value of which is zero for no deformation and becomes increasingly greater as angle BAC increases. Shear strains are also dimensionless.

 

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