"Wooden" and "Heartwood"
Wood could be a porous and fibrous structural tissue found within the stems and roots of trees and different woody plants. It's been used for thousands of years for each fuel and as a construction material. it's Associate in Nursing organic material, a natural composite of polyose fibers (which area unit sturdy in tension) embedded in an exceedingly matrix of likning that resists compression. Wood is typically outlined as solely the secondary vascular tissue within the stems of trees, or it's outlined additional broadly speaking to incorporate identical form of tissue elsewhere like within the roots of trees or shrubs. in an exceedingly living tree it performs a support operate, sanctionative woody plants to grow massive or to face up by themselves. It additionally conveys water and nutrients between the leaves, different growing tissues, and also the roots. Wood may additionally consult with different plant materials with comparable properties, and to material designed from wood, or wood chips or fiber.
The Earth contains concerning one trillion tonnes of wood, that grows at a rate of ten billion tonnes per annum. As Associate in Nursing teeming, carbon-neutral natural resources, woody materials are of intense interest as a supply of renewable energy. In 1991, about three.5 cuboid kilometers of wood were harvested. Dominant uses were for piece of furniture and building construction.
History
A 2011 discovery within the province of latest Brunswick uncovered the earliest proverbial plants to possess adult wood, about 395 to four hundred million years past. Wood is dated by carbon-14 dating and in some species by dendrochronology to form inferences concerning once a wood object was created.
People have used wood for millennia for several functions, primarily as a fuel or as a construction material for creating homes, tools, weapons, furniture, packaging, artworks, and paper. The year-to-year variation in tree-ring widths and atom abundances provides clues to the prevailing climate at that point.
Physical properties
Diagram of secondary growth in an exceedingly tree showing idealized vertical and horizontal sections. a brand new layer of wood is superimposed in every season, thickening the stem, existing branches and roots, to make a annual ring.
Growth rings
Wood, within the strict sense, is yielded by trees, that increase in diameter by the formation, between the present wood and also the inner bark, of latest woody layers that enclose the whole stem, living branches, and roots. This method is understood as secondary growth; it's the results of cellular division within the tube-shaped structure cambium, a lateral plant tissue, and resultant growth of the new cells. wherever there area unit clear seasons, growth will occur in an exceedingly separate annual or seasonal pattern, resulting in growth rings; these will typically be most clearly seen on the tip of a log, however are visible on the opposite surfaces. If these seasons area unit annual these growth rings area unit brought up as annual rings. wherever there's no seasonal distinction growth rings area unit doubtless to be vague or absent.
If there area unit variations among a annual ring, then the a part of a annual ring nearest the middle of the tree, and fashioned early within the season once growth is speedy, is sometimes composed of wider components. it's typically lighter in color than that close to the outer portion of the ring, and is understood as earlywood or springwood. The outer portion fashioned later within the season is then referred to as the latewood or summerwood. However, there area unit major variations, counting on the type of wood (see below).
Knots
A knot on a tree at the Garden of the Gods public park in city, A knot could be a explicit form of state in an exceedingly piece of wood; it'll have an effect on the technical properties of the wood, typically for the more serious, however could also be exploited for visual result. in an exceedingly longwise sawn plank, a knot can seem as a roughly circular "solid" (usually darker) piece of wood around that the grain of the remainder of the wood "flows" (parts and rejoins). among a knot, the direction of the wood (grain direction) is up to ninety degrees completely different from the grain direction of the regular wood.
In the tree a knot is either the bottom of a aspect branch or a dormant bud. A knot in shape (hence the roughly circular cross-section) with the inner tip at the purpose in stem diameter at that the plant's tube-shaped structure cambium was set once the branch fashioned as a bud.
During the event of a tree, the lower limbs typically die, however might stay hooked up for a time, typically years. resultant layers of growth of the attaching stem are not any longer intimately joined with the dead limb, however area unit adult around it. Hence, dead branches turn out knots that don't seem to be hooked up, and certain to drop out when the tree has been sawn into boards.
In grading lumber and structural timber, knots area unit classified in keeping with their kind, size, soundness, and also the firmness with that they're control in situ. This firmness is tormented by, among different factors, the length of your time that the branch was dead whereas the attaching stem continued to grow.
Wood knot in mechanical drawing
"Knots materially have an effect on cracking and distortion, ease in operating, and cleavability of timber. they're defects that weaken timber and lower its price for structural functions wherever strength is a crucial thought. The weakening result is far additional serious once timber is subjected to forces perpendicular to the grain and/or tension than wherever below load on the grain and/or compression. The extent to that knots have an effect on the strength of a beam depends upon their position, size, number, and condition. A knot on the top side is compressed, whereas one on the lower aspect is subjected to tension. If there's a season sign on the knot, as is commonly the case, it'll provide very little resistance to the present tensile stress. tiny knots, however, could also be set on the neutral plane of a beam and increase the strength by preventing longitudinal cutting. Knots in an exceedingly board or plank area unit least injurious after they extend through it at right angles to its broadest surface. Knots that occur close to the ends of a beam don't weaken it. Sound knots that occur within the central portion simple fraction the peak of the beam from either edge don't seem to be serious defects.
Knots don't essentially influence the stiffness of structural timber, this can rely on the scale and placement. Stiffness and elastic strength area unit additional dependent upon the sound wood than upon localized defects. The breaking strength is extremely at risk of defects. Sound knots don't weaken wood once subject to compression parallel to the grain.
In some ornamental applications, wood with knots could also be fascinating to feature visual interest. In applications wherever wood is painted, like peripheral boards, facia boards, door frames and piece of furniture, resins gift within the timber might still 'bleed' through to the surface of a knot for months or perhaps years when manufacture and show as a yellow or dark-brown stain. A knot primer paint or resolution, properly applied throughout preparation, might do abundant to scale back this downside however it's troublesome to regulate fully, particularly once mistreatment factory-made kiln-dried timber stocks.
Wood could be a porous and fibrous structural tissue found within the stems and roots of trees and different woody plants. It's been used for thousands of years for each fuel and as a construction material. it's Associate in Nursing organic material, a natural composite of polyose fibers (which area unit sturdy in tension) embedded in an exceedingly matrix of likning that resists compression. Wood is typically outlined as solely the secondary vascular tissue within the stems of trees, or it's outlined additional broadly speaking to incorporate identical form of tissue elsewhere like within the roots of trees or shrubs. in an exceedingly living tree it performs a support operate, sanctionative woody plants to grow massive or to face up by themselves. It additionally conveys water and nutrients between the leaves, different growing tissues, and also the roots. Wood may additionally consult with different plant materials with comparable properties, and to material designed from wood, or wood chips or fiber.
The Earth contains concerning one trillion tonnes of wood, that grows at a rate of ten billion tonnes per annum. As Associate in Nursing teeming, carbon-neutral natural resources, woody materials are of intense interest as a supply of renewable energy. In 1991, about three.5 cuboid kilometers of wood were harvested. Dominant uses were for piece of furniture and building construction.
History
A 2011 discovery within the province of latest Brunswick uncovered the earliest proverbial plants to possess adult wood, about 395 to four hundred million years past. Wood is dated by carbon-14 dating and in some species by dendrochronology to form inferences concerning once a wood object was created.
People have used wood for millennia for several functions, primarily as a fuel or as a construction material for creating homes, tools, weapons, furniture, packaging, artworks, and paper. The year-to-year variation in tree-ring widths and atom abundances provides clues to the prevailing climate at that point.
Physical properties
Diagram of secondary growth in an exceedingly tree showing idealized vertical and horizontal sections. a brand new layer of wood is superimposed in every season, thickening the stem, existing branches and roots, to make a annual ring.
Growth rings
Wood, within the strict sense, is yielded by trees, that increase in diameter by the formation, between the present wood and also the inner bark, of latest woody layers that enclose the whole stem, living branches, and roots. This method is understood as secondary growth; it's the results of cellular division within the tube-shaped structure cambium, a lateral plant tissue, and resultant growth of the new cells. wherever there area unit clear seasons, growth will occur in an exceedingly separate annual or seasonal pattern, resulting in growth rings; these will typically be most clearly seen on the tip of a log, however are visible on the opposite surfaces. If these seasons area unit annual these growth rings area unit brought up as annual rings. wherever there's no seasonal distinction growth rings area unit doubtless to be vague or absent.
If there area unit variations among a annual ring, then the a part of a annual ring nearest the middle of the tree, and fashioned early within the season once growth is speedy, is sometimes composed of wider components. it's typically lighter in color than that close to the outer portion of the ring, and is understood as earlywood or springwood. The outer portion fashioned later within the season is then referred to as the latewood or summerwood. However, there area unit major variations, counting on the type of wood (see below).
Knots
A knot on a tree at the Garden of the Gods public park in city, A knot could be a explicit form of state in an exceedingly piece of wood; it'll have an effect on the technical properties of the wood, typically for the more serious, however could also be exploited for visual result. in an exceedingly longwise sawn plank, a knot can seem as a roughly circular "solid" (usually darker) piece of wood around that the grain of the remainder of the wood "flows" (parts and rejoins). among a knot, the direction of the wood (grain direction) is up to ninety degrees completely different from the grain direction of the regular wood.
In the tree a knot is either the bottom of a aspect branch or a dormant bud. A knot in shape (hence the roughly circular cross-section) with the inner tip at the purpose in stem diameter at that the plant's tube-shaped structure cambium was set once the branch fashioned as a bud.
During the event of a tree, the lower limbs typically die, however might stay hooked up for a time, typically years. resultant layers of growth of the attaching stem are not any longer intimately joined with the dead limb, however area unit adult around it. Hence, dead branches turn out knots that don't seem to be hooked up, and certain to drop out when the tree has been sawn into boards.
In grading lumber and structural timber, knots area unit classified in keeping with their kind, size, soundness, and also the firmness with that they're control in situ. This firmness is tormented by, among different factors, the length of your time that the branch was dead whereas the attaching stem continued to grow.
Wood knot in mechanical drawing
"Knots materially have an effect on cracking and distortion, ease in operating, and cleavability of timber. they're defects that weaken timber and lower its price for structural functions wherever strength is a crucial thought. The weakening result is far additional serious once timber is subjected to forces perpendicular to the grain and/or tension than wherever below load on the grain and/or compression. The extent to that knots have an effect on the strength of a beam depends upon their position, size, number, and condition. A knot on the top side is compressed, whereas one on the lower aspect is subjected to tension. If there's a season sign on the knot, as is commonly the case, it'll provide very little resistance to the present tensile stress. tiny knots, however, could also be set on the neutral plane of a beam and increase the strength by preventing longitudinal cutting. Knots in an exceedingly board or plank area unit least injurious after they extend through it at right angles to its broadest surface. Knots that occur close to the ends of a beam don't weaken it. Sound knots that occur within the central portion simple fraction the peak of the beam from either edge don't seem to be serious defects.
Knots don't essentially influence the stiffness of structural timber, this can rely on the scale and placement. Stiffness and elastic strength area unit additional dependent upon the sound wood than upon localized defects. The breaking strength is extremely at risk of defects. Sound knots don't weaken wood once subject to compression parallel to the grain.
In some ornamental applications, wood with knots could also be fascinating to feature visual interest. In applications wherever wood is painted, like peripheral boards, facia boards, door frames and piece of furniture, resins gift within the timber might still 'bleed' through to the surface of a knot for months or perhaps years when manufacture and show as a yellow or dark-brown stain. A knot primer paint or resolution, properly applied throughout preparation, might do abundant to scale back this downside however it's troublesome to regulate fully, particularly once mistreatment factory-made kiln-dried timber stocks.