test element
1, the mechanical properties (machnicalproperties) : various mechanical properties when the material subject to an external force manifested. The reaction
by an external force when the external force the material inside the material:
2, the stress (stress). Magnitude of the stress is represented by the following equation: stress (δ) = action (F) / unit area of material (A), a unit of Pa.
3, strain (strain):
When the material deformation caused by external force. Strain magnitude represented by the following equation: strain (ε) = change in length (△ L) / initial length (L).
4, tensile stress or tensile stress (tensilestress):
material is subjected to an internal tensile stress.
5, compressive stress or compressive stress (compressivestress):
material is subjected to an internal compressive stress.
6, shear stress (shearstress):
when the material is subjected to dislocation shear force, the internal stress during sliding parallel portion occurs.
However, when a certain period of restoration material or when a force, often exist in the form of three kinds of stress. Pressure is applied to the chewing e.g. fixed bridge, the bridge Ni surface receives a force is a compressive stress, the gingival end of the bridge compared with tensile stress, and the dental restoration base junction bridge as shear stress.
7, the tensile strength or tensile strength (tensilestrength)
8, compressive strength or compressive strength (compressivestrength):
is applied on the specimen compressive load to the load value per unit area of the specimen at failure. Unit when
, also known as flexural strength or flexural strength, load is applied between the two points of the specimen to specimen damage:
9, bending strength (bendingstrength) area load value.
formula
three-point bending test formula:
R = (3F * L) / (2b * h * h)
< p> F- breaking loadL- span
b- width
h- thickness
test method
GB bending strength (GB / T 6569-86), or ISO 14704-2000 measured
a test sample (35 × 3 × 4) follows the standard "test method" FIG.
is divided into three point bending flexural strength test and four-point bending. Each point to be above the average results of five data (standard data to 10). FIG "bending strength" FIG.
flexural strength testing was performed on Imperial Instron1195 universal testing machine. Was used as the test strip 3 × 4 × 35 (mm * mm * mm). Measured using three-point bending span of 30mm, loading rate of 0.5mm / min. Data for each five test bars, and then averaged.
Other related concepts
1, the hardness (hardness):
dishing resistance material other hard objects caused by press-fitting. Common units Brinell hardness (HB or BHN), Vickers hardness (Hv or VHN), Rockwell hardness (HRA, HRC or RHN) slave hardness (HK or KHN).
surface hardness of the material is the result of a variety of properties strength, proportional limit, toughness, ductility and wear resistance, cut resistance and the like.
2, the impact strength (impactstrength):
material under impact force required to break the energy.
3, ductility and malleability (ductilityandmalleability):
ductile material is under tension without breaking the ability to undergo permanent deformation. Malleable material is subjected to pressure without breaking capability of permanent deformation.
4, proportional limit (proportionallimit):
material is subjected to an external force, the stress and strain to maintain the maximum stress value proportional relationship.
5, the elastic modulus (modulusofelasticity):
in the proportional limit, the ratio of stress and strain.
6, rheological (flow):
substance amorphous structure under continuous stress sustained permanent deformation properties. Liquid and paste rheology is typically measured by viscosity.
7, creep (creepage):
crystal structure of the substance under continuous stress permanent deformation properties. Wax and amalgam creep is likely to occur, and increases with time.
8, wettability (wetting):
in liquid or paste on the surface of the solid dispersing ability. It is usually expressed by the contact angle "θ", the representative surface penetration ability, it is related to the surface energy.
9, adhesion and cohesion (adhesionandcohesion):
adhered to the surface of the two materials the adhesive, and the bonding between the same kind of material is cohesive.
sample processing
Note that the sample should be consistent with the rubbing direction in the longitudinal direction when processed surface.
coarse fraction and fine grinding two processes.
depth of each no more than coarse 0.03mm.
using finely ground object 320 ~ 800 diamond grinding wheel, each grinding depth not exceeding 0.002mm.