JIS K 6394 Rubber, Vulcanized or Thermoplastic - Determination of Dynamic Properties - General Guide

The standard “JIS K 6394 Rubber, vulcanized or thermoplastic - Determination of dynamic properties - General guide” developed by the Japanese Industrial Standards Organization (JIS) describes free vibration methods and forced vibration methods for vulcanized rubber and thermoplastic rubber (including products). This standard provides general guidelines on how to obtain dynamic properties. However, impact strength and cyclic fatigue tests are outside the scope of this standard.

This standard is essentially based on the standard "ISO 4664-1 Rubber, vulcanized or thermoplastic - Determination of dynamic properties - Part 1: General guide" published by the International Organization for Standardization (ISO). This international standard is designed to provide guidance on the determination of dynamic properties of vulcanized and thermoplastic rubbers. It includes both free and forced vibration methods performed on both materials and products. It does not cover rebound resilience or cyclic tests where the main objective is to fatigue the rubber.

For the purposes of the JIS K 6394 standard, the following terms and definitions apply:

• A hysteresis loop is a closed curve representing the successive stress-strain states of a material during cyclic deformation.
• Energy loss is the energy per unit volume lost in each deformation cycle, i.e., the area of ​​the hysteresis loop.
• Power loss is expressed as the energy loss per unit time, per unit volume, converted into heat through hysteresis, the product of energy loss and frequency.
• The mean stress is the average value of the stress during a single complete hysteresis cycle. It is expressed in Pa. This is the static stress applied before the dynamic motion begins. The equilibrium mean stress and mean stress are shown as time averages of the instantaneous stress and stress, for obvious initial cycles. A sinusoidal response to a sinusoidal motion refers to hysteresis loops that are or can be considered elliptical. For large sinusoidal deformations, the hysteresis loop will deviate from an ellipse because the stress-strain relationship for rubber is nonlinear and therefore the response is not sinusoidal. The term incremental can be used to refer to a dynamic response to a sinusoidal deformation about various levels of mean stress or mean strain (e.g., incremental spring constant, incremental elastic shear modulus).
• Mean strain is the average value of strain during a single complete hysteresis cycle. This is the static strain applied before dynamic motion begins.
• Maximum load amplitude, the maximum applied load, is measured from the average value of the load during a single sinusoidal wave.
• The maximum stress amplitude is the ratio of the maximum applied force, measured from the average force, to the cross-sectional area of ​​the unstressed test piece (zero to peak on one side only). It is expressed in Pa.
• The maximum deviation amplitude is the maximum value of the deviation measured from the average value of the deviation during a single sinusoidal wave.
• Maximum strain amplitude, the maximum value of strain, is measured from the average strain (from zero to peak on one side only)
• The Payne effect is the phenomenon in which, in dynamic testing of a filled rubber compound, the dynamic modulus decreases as the strain increases.

Dynamic property tests are used to compare and evaluate material properties, design materials, product performance, and similar criteria. Dynamic property test results depend on strain, stress, frequency, test temperature, specimen shape, and similar characteristics. This is largely limited by such influences as test equipment capacity, linearity of the hysteresis curve, and internal heat generation of the test piece. Therefore, these items need to be specified and adjusted when comparing results. More importantly, the conditions and equipment for obtaining the data must be appropriate for the test purpose.

Appropriate equipment for evaluating material properties, such as small test equipment, can be used to collect data for design documents or to measure product properties. In some cases, it may not be possible to measure under test conditions such as frequency, amplitude, deformation method.

Dynamic property tests are selected depending on the purpose of the test, vibration method or deformation method.

The classification of dynamic property tests is as follows:

• According to the purpose of the test:
  • With small test equipment: Comparison and evaluation of material properties
  • With large test equipment: Comparison and evaluation of design materials and product performance
• According to the vibration method:
  • With small test equipment: Forced vibration non-resonant method
  • With large testing equipment: forced vibration non-resonance method, forced vibration resonance method and free vibration method
• See conversion method:
  • With small testing equipment: Tensile method, bending method, compression method and shear method
  • With large testing equipment: compression method, tension method, torsion method and shear method
• According to the shape of the test piece:
  • With small test equipment: Rectangular, cylindrical and prismatic
  • With large testing equipment: Cylindrical, prismatic and conical and products

Equipment used in tests typically includes:

• Vibrator stand
• Vibrator
• Crosshead
• detector
• Sample holders or fixtures
• Thermostatic oven
• Control circuit section
• Data processing unit

Among the numerous tests, measurements, analyses and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the standard “JIS K 6394 Rubber, vulcanized or thermoplastic - Determination of dynamic properties - General guide” with its trained and expert staff and advanced technological equipment.