Material Properties Definition

Material Properties Definition

• Material properties are identified by a value or quantity with an associated unit of measurement.
• Most material information in literature or technical datasheets is represented in this way.

Rheological Properties

• Molding shrinkage (parallel) is 0.95% as per ISO 294-4.
• Molding shrinkage (normal) is 0.95% as per ISO 294-4.

Mechanical Properties

• Tensile modulus is 3200/1000 MPa as per ISO 527-1/-2.
• Yield stress is 85/45 MPa as per ISO 527-1/-2.
• Yield strain is 4/25% as per ISO 527-11-2.
• Nominal strain at break is 20/>50% as per ISO 527-11-2.
• Flexural modulus is 2600/- MPa as per ISO 178.
• Flexural strength is 100/- MPa as per ISO 178.
• Charpy impact strength at +23°C is N/N kJ/m² as per ISO 179/1eU.
• Charpy impact strength at -30°C is N/N kJ/m² as per ISO 179/1eU.
• Charpy notched impact strength at +23°C is 8/35 kJ/m² as per ISO 179/1EA.
• Charpy notched impact strength at -30°C is 5/5 kJ/m² as per ISO 179/1eA.

Thermal Properties

• Melting temperature at 10°C/min is 220/* °C as per ISO 11357-1/-3.
• Temperature of deflection under load at 1.80 MPa is 65/* °C as per ISO 75-1/-2.
• Temperature of deflection under load at 0.45 MPa is 185/* °C as per ISO 75-1/-2.
• Coefficient of linear thermal expansion (parallel) is 0.9/* 10⁴/°C as per ISO 11359-1/-2.
• Coefficient of linear thermal expansion (normal) is 1/* 10⁴/°C as per ISO 11359-11-2.
• Burning behavior at 1.5 mm nominal thickness is V-2/* class as per IEC 60695-11-10.
• Thickness tested for burning behavior is 1.5/* mm as per IEC 60695-11-10.
• Burning behavior at thickness h is V-2/* class as per IEC 60695-11-10.
• Thickness tested for burning behavior at thickness h is 0.75/* mm as per IEC 60695-11-10.
• Oxygen index is 26/* % as per ISO 4589-1/-2.

Electrical Properties

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Intrinsic Property Definition

• Intrinsic properties cannot be identified without an external stimulus and measuring the material's response.
• A property is defined by measuring the material's response to a stimulus.

Schematic Analysis of Measuring Material Properties

• The measurement process involves applying a stimulus (input) and recording the material's response (output).
• Examples of stimuli and responses:
  • Mechanical force → Displacement
  • Electric voltage → Current intensity
  • Temperature gradient → Heat flow
  • Light radiation → Colour

Stimulus and Response

• The stimulus can be any chemical-physical entity, such as mechanical force, electric voltage, or temperature gradient.
• The response can be of the same nature as the stimulus (e.g., deformation from a force) or different (e.g., piezoelectric materials generating electrical polarization from deformation).
• The material response is not a property in itself, but rather a relationship between the stimulus and response.

Property Definition

• A property is a quantity defined through an equation or function.
• The function is usually multi-variable, considering factors such as:
  • Type of stress applied (force, strain, etc.)
  • Geometry of the body and boundary conditions (beam, plate, bending, torsion, etc.)
  • Environmental conditions
  • Observation time
  • Structural state of the material

Material Behavior and Characterization

• The load curve of a material can be described by specific points, such as the yield stress, ultimate strength, and fracture point, but this approach provides a limited description of the material's behavior.
• The traditional method of characterizing material behavior using single values has limitations, leading to the development of a new approach based on functions instead of single values.

Multipoint Data Representation

• The ISO 11403 standard, published in 1999, provides a new methodology for representing materials data using multipoint data.
• Multipoint data representation can capture the trend of a property when certain characteristic variables of the physical phenomenon under examination vary.
• Examples of multipoint data representation include rheological and isochronous stress-strain curves.

Intrinsic Material Properties

• Intrinsic material properties are independent of the shape, size, and boundary conditions of the physical system on which the property is measured.
• Examples of intrinsic material properties include fracture toughness, magnetic susceptibility, electrical dielectric constant, optical refractive index, thermal conductivity, and physical density.
• Intrinsic material properties are essential for engineering design, as they can be used with confidence and reliability for designing components.

Continuum Mechanics

• Continuum mechanics is a theory that assumes material subjected to mechanical action maintains its continuity, and the effect of applying a stress at one point propagates instantaneously to all points of the body.
• The theory is applicable when the stresses or strains are kept low (infinitesimal).

Stress and Strain

• Stress is defined as the force normalized with respect to the geometry, obtained by dividing the applied force by the cross-sectional area of the specimen.
• Strain is defined as the elongation of the specimen divided by its initial length.
• The stress acting at a point in a body can be defined by imagining to cut the body with a plane through the point, showing the internal forces acting on the imaginary surface.

Stress Tensor

• The stress tensor is a set of vectors acting at a point in the body, which can be represented by a matrix of nine scalar components.
• The stress tensor can be decomposed into scalar quantities by projecting the stress vectors along each reference axis.
• The stress tensor can be used to describe the state of stress at a point in the body, including normal and shear stresses.