ASTM C1198 Measuring Dynamic Young’s Modulus, Shear Modulus, and Poisson’s Ratio

Get Certified ASTM C1198 Testing

ASTM C1198 testing helps manufacturers, ceramic producers, engineers, material researchers, quality-control professionals, and technicians characterize the dynamic elastic behavior of advanced ceramic materials. During testing, technicians prepare a suitable rectangular or cylindrical specimen, accurately measure its dimensions and mass, and mechanically excite it to identify its fundamental flexural and torsional resonant frequencies. Analysts use these measurements with the applicable calculations to determine dynamic Young’s modulus, dynamic shear modulus, and Poisson’s ratio. Certified or qualified ASTM C1198 testing can provide reliable material-property data for ceramic development, quality control, engineering evaluation, and comparison of advanced ceramic formulations.

• Material Type: Advanced ceramic materials suitable for resonance testing.
• Dynamic Young’s Modulus: Determined from the fundamental flexural resonant frequency.
• Dynamic Shear Modulus: Determined from torsional resonant vibration.
• Poisson’s Ratio: Calculated using the dynamic Young’s modulus and shear modulus.
• Specimen Geometry: Rectangular or cylindrical specimens can be used when suitable for the test.
• Material Condition: Particularly appropriate for elastic, homogeneous, and isotropic ceramics.
• Composite Ceramics: Particulate-, whisker-, or fiber-reinforced ceramics may be evaluated, but reinforcement characteristics must be considered when interpreting results.
• Temperature Testing: The method describes provisions for measuring dynamic elastic moduli over approximately -195 to 1200 °C.
• Limitations: The method is not suitable for specimens containing major cracks or voids or for materials that cannot be fabricated with an appropriate uniform rectangular or circular cross section.
• Units: SI units are the standard units for the method.

What are the uses of ASTM C1198 testing?

ASTM C1198 offers dynamic elastic property values, which can be used to gain an understanding of how advanced ceramics are able to respond to small, rapidly applied mechanical stresses. The method is non-destructive, so that often specimens can be assessed without causing significant harm. The sonic-resonance approach is very beneficial to the development and characterization of ceramics and can also be beneficial to quality-control programs. It can be very helpful in cases where measurements need to be performed at high or cryogenic temperatures, where static-loading measurements might be influenced by delayed elastic or creep behavior.  Common uses include:

• Material Characterization: Determining dynamic elastic properties of advanced ceramics.
• Material Development: Comparing ceramic formulations, compositions, and processing conditions.
• Design Data Generation: Providing modulus data for engineering calculations and component design.
• Quality Control: Establishing acceptable resonant-frequency ranges for specimens with controlled geometry and mass.
• Research and Development: Studying the influence of composition, processing, microstructure, and reinforcement on elastic behavior.
• Temperature-Dependent Evaluation: Measuring changes in dynamic modulus over elevated or cryogenic temperature ranges.
• Nondestructive Evaluation: Screening ceramic components for defects such as cracks, voids, porosity, or density variations that can affect resonant frequency.
• Material Comparison: Comparing dynamic elastic behavior between advanced ceramic materials.

Which Materials Can Be Tested According to ASTM C1198?

ASTM C1198 is intended primarily for advanced ceramics that are elastic, homogeneous, and isotropic. The method can also be applied to advanced ceramic composites, including particulate-, whisker-, and fiber-reinforced materials, provided that the influence of the reinforcement is considered when interpreting the measured elastic properties. Materials may include:

• Advanced structural ceramics
• Alumina-based ceramics
• Silicon carbide ceramics
• Silicon nitride ceramics
• Zirconia-based ceramics
• Other homogeneous advanced ceramic compositions
• Particulate-reinforced ceramic composites
• Whisker-reinforced ceramic composites
• Fiber-reinforced ceramic composites

Why is ASTM C1198 Testing Important?

ASTM C1198 provides quantitative dynamic elastic-property data without requiring conventional destructive loading to fracture or permanently deform the specimen. The method measures resonant behavior at very small strains, making it useful for characterization of advanced ceramics while minimizing the possibility of specimen damage. The resulting modulus values can support engineering analysis, material selection, product development, quality-control programs, and research. Resonance measurements can also reveal changes in elastic response associated with defects or variations in ceramic structure.

ASTM C1198 Testing Process and Data Collection

Technicians first identify and prepare the advanced ceramic specimen and measure its mass and dimensions. The specimen is then suspended or supported in a manner that permits free vibration, and the transducers are positioned to excite and detect the required vibration mode. For flexural testing, the frequency is varied until the fundamental flexural resonance is identified. For torsional testing, the specimen and transducer or support arrangement is adjusted to produce and detect torsional resonance. The technician records specimen identification, geometry, dimensions in mm, mass, temperature, vibration mode, resonant frequencies in Hz, and other applicable test conditions. The analyst uses the measured resonant frequencies together with specimen geometry and mass to calculate dynamic Young’s modulus and dynamic shear modulus and then determines Poisson’s ratio from the applicable relationship.

Common Challenges and Troubleshooting

Accurate specimen dimensions and mass are important because errors in these measurements can affect calculated elastic properties. Technicians should use calibrated dimensional and mass-measurement equipment and take measurements at the required locations along the specimen. The technicians should differentiate the fundamental mode from overtones based on the vibration pattern, node and anti-node location, or applicable frequency response. If the specimen is not very well supported or if too much contact is made with the transducer, the free vibration can be limited, and the measured resonance will be different. Stability should, therefore, be adequate, but mechanical interference should be kept to a minimum by supports. Additionally, overall specimen geometry, cracks, voids, excess porosity, and specimen geometry can affect accurate resonance.

• Dynamic Young’s modulus is calculated from the fundamental flexural resonant frequency, while dynamic shear modulus is calculated from the applicable torsional resonant frequency. Poisson’s ratio is then determined from the dynamic Young’s modulus and dynamic shear modulus.
• Young’s modulus and shear modulus are generally reported in GPa or MPa, while Poisson’s ratio is dimensionless. Resonant frequencies are reported in Hz, and specimen dimensions are recorded in mm. Temperature is reported in °C when temperature-dependent testing is performed.
• The technician records specimen identification, material description, specimen geometry, length, width, thickness or diameter in mm, mass, resonant frequencies in Hz, temperature, and applicable equipment or test configuration.
• The analyst documents the fundamental flexural and torsional resonant frequencies, calculated dynamic Young’s modulus, calculated dynamic shear modulus, Poisson’s ratio, and any relevant observations concerning specimen condition or resonance response.
• The report includes the specimen identification, description of the ceramic material, specimen geometry, dimensions, mass, vibration mode, resonant frequencies, test temperature, calculated elastic properties, and applicable test conditions. 
• All technicians and analysts can generate consistent, reliable, and comparable ASTM C1198 results through standardized measurement of dimensions, mass, resonance excitation, frequency detection, temperature control, equipment verification, and calculation procedures.

Link to ASTM C1198