Strength Properties of Wood Flashcards
Ability to resist applied stress and the strength of the wood is synonymous with the resistance of the wood (Hoadley, 2000)
STRENGTH
- the property of a material that exhibits both viscous and elastic characteristics under stress and deformation, so it has properties of both the solid and the liquid phase.
VISCOELASTICITY
Strength Properties:
- MODULUS OF RUPTURE
- MODULUS OF ELASTICITY
- BENDING STRENGTH
- IMPACT BENDING TEST
- STIFFNESS
- TOUGHNESS/SHOCK RESISTANCE
- WORK TO PROPORTIONAL LIMIT
- WORK TO MAXIMUM LOAD
- HARDNESS
- JANKA HARDNESS TEST
- TENSILE STRENGTH
- COMPRESSIVE STRENGTH
- SHEARING STRENGTH
- Tensile Strength perpendicular
to the grain - Tensile Strength parallel to the
grain - SHEAR STRENGTH PARALLEL TO THE GRAIN
- COMPRESSIVE STRENGTH PARALLEL TO THE GRAIN
- ULTIMATE STRENGTH
- CLEAVAGE
- TORSION STRENGTH
- TOUGHNESS
- CREEP & DURATION OF LOAD
- FATIGUE
- ROLLING SHEAR STRENGTH
- NANOINDENTATION HARDNESS
- FRACTURE TOUGHNESS
✓Maximum capacity of a wood to carry a certain load
up to its breaking point.
✓Not considered a part of the stress imposed in the
wood.
MODULUS OF RUPTURE
✓Refers to the degree of a wood
✓Occurs when wood recovers its original shape and size
after stress is removed.
MODULUS OF ELASTICITY
Resistance of wood to bend when
applied with load.
BENDING STRENGTH
–bending caused by
load
DEFLECTION
2 Types of Bending:
- Static
- Impact
– stationary or at rest
Static
– sudden loading and can be
used to measure the toughness property of wood.
Impact
✓A hammer w/ specified weight is dropped upon a
wood from various heights until the wood ruptures
around 152 mm (6 in).
✓Height that causes the wood to deflect is considered its
ability to absorb shocks that cause stresses beyond the
proportional limit.
IMPACT BENDING TEST
✓ Ability of wood to preserve its original size and shape
STIFFNESS
✓Ability of wood to absorb shock energy.
TOUGHNESS/SHOCK RESISTANCE
✓Ability of wood to absorb shock without causing permanent damage
WORK TO PROPORTIONAL LIMIT
✓Ability of wood to absorb shock with permanent
damage or injury
✓Used to measure the combined strength and toughness
of wood under bending stresses.
WORK TO MAXIMUM LOAD
✓Ability of wood to resist indention or force
✓The _______ of wood increases as it loses moisture
below fiber saturation point.
HARDNESS
✓ Use to measure the resistance of
a sample of wood to denting and wear.
✓ Measures the force required to embed an 11.28 mm (0.444 in) diameters steel ball halfway into a sample of wood to determine whether a species is suitable for use as a flooring.
JANKA HARDNESS TEST
✓Ability of the wood to resist deformation as a result of
applied force or load tending to pull the wood apart.
TENSILE STRENGTH
✓Ability of the wood to resist crushing due to applied
force tending to shorten the wood.
COMPRESSIVE STRENGTH
✓Ability of the wood to resist force causing one part of
the material to slip on adjacent part.
SHEARING STRENGTH
✓ Ability of the wood to resist a force causing one part of the material to slip on adjacent part.
Tensile Strength perpendicular
to the grain.
✓ Resistance of wood to resist a force causing one part of the material to slip on adjacent part.
Tensile Strength parallel to the
grain.
✓Resistance to internal slipping of one part upon another
along the grain.
SHEAR STRENGTH PARALLEL TO THE GRAIN.
✓Ability of wood to resist maximum stress sustained by a
compression parallel to the grain
COMPRESSIVE STRENGTH PARALLEL TO THE GRAIN
✓Ability of the wood to resist the greatest static load which a body can support when tested to complete failure.
ULTIMATE STRENGTH
✓ Ability of the wood to resist from
splitting.
✓ Is of importance when wood is to be nailed or bolted.
CLEAVAGE
✓ Resistance of wood to twisting in the longitudinal axis.
✓_______ strength may also refer to shear strength parallel to grain.
TORSION STRENGTH
✓Required energy to cause complete failure rapidly in a
centrally loaded bending wood specimen.
TOUGHNESS
✓Time dependent deformation of wood under load
✓If the load is high and the duration of load is long, failure
(creep-rupture) will eventually occur.
CREEP & DURATION OF
LOAD
✓Resistance to failure under specific combinations od
cyclic loading conditions: frequency and no. of cycles;
maximum stress; ratio of maximum to minimum stress; and
other less- important factors.
FATIGUE
✓ The shearing strength of wood where shearing force is in a longitudinal plane and is acting perpendicular to the grain.
ROLLING SHEAR
STRENGTH
✓ Uses an extremely small indenter of a hard material and specified shape (usually a pyramid) to press into the surface with sufficient force that the wood deforms.
NANOINDENTATION HARDNESS
✓ Ability of the wood to withstand flaws that initiate failure.
FRACTURE TOUGHNESS
