Development and validation of a method for linear-viscoelastic characterization of the dynamic complex modulus of short-fiber reinforced plastics using flexural resonances. (February 2021)

• Record Type: Journal Article
• Authors: Urban, Fabian; Armbruster, Bo; Middendorf, Peter
• Is Part Of: Polymer testing. Volume 94(2021)
• Publication Date: 2021-02
• Subjects: Complex modulus -- Linear-viscoelasticity -- Frequency dependence -- Flexural vibration -- Short fiber; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2021.107055
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: At present, the simulation cannot satisfactorily reproduce the actual vibration behavior of short-fiber reinforced plastics. This is because the required linear-viscoelastic material properties, in particular damping, are often not useable in the desired frequency range of up to 10 kHz. For this purpose, a newly reconsidered test method as an alternative to the established dynamic mechanical analysis is developed which can determine the stiffness and damping of the material for a wide frequency range, taking into account ambient conditions such as temperature and humidity as well as fiber orientation. Cuboid specimens are excited in a climatic chamber using an electromechanical shaker and their flexural vibration behavior is characterized with a laser vibrometer. Material properties can be directly determined up to a frequency of 10 kHz at constant humidity and in a temperature range from −30 °C to 200 °C. A validation is performed on specimens made out of short-fiber reinforced thermoplastic. An automotive powertrain application example is used but the test method is universally applicable for any field of activity using reinforced and non-reinforced material with sufficient stiffness for flexural vibrations in the desired frequency range. Highlights: Newly reconsidered test method for vibration analysis of fiber-reinforced plastics. Direct Characterization of viscoelastic material properties up to 10 kHz and 200 °C. Frequency, temperature and humidity dependent material properties. Specimens are not clamped but fixed with a 2-component epoxy resin. Measurement of the direct excitation force induced into the specimens.