Dynamic modulus measurements are of interest in materials research not only as a source of data on elastic behavior, but also for the insight they provide into structure-property relationships in general. A description is given of a vibrating-reed apparatus which has proved highly adaptable for studies of the elastic and damping behavior of thin-film and other thin-layer electronic materials. Results are reported for amorphous and crystalline ferromagnetic materials, for the high-Tc superconducting oxide Y1Ba2Cu3O7-x, and for thin films of aluminum and silicon monoxide, to illustrate the important role which the dynamic modulus can play as a tool in materials research.

One of the most common methods used in road-pavement construction is the stabilizing of the conventional pavement base course layer. This is achieved by adding cement or lime to gain better material performance. However, obtaining modulus input parameters from a cement-stabilized base course layer for pavement-response analysis under real traffic conditions has proven difficult in that, to date, only ambiguous results have been produced. Using the flexural modulus or elastic modulus in the response analysis has certain limitations in embracing real pavement behavior under traffic and temperature conditions. Accordingly, a more reliable modulus input parameter for pavement analysis under traffic (cyclic) loads is required to obtain more precise and reliable outputs. Moreover, there is, at present, no test protocol to determine a suitable modulus for a cement-stabilized base material under the cyclic loading regime. This study aims to examine the real dynamic responses of cement-stabilized base course materials with a view to adapting the asphalt mixture performance tester (AMPT), a specifically designed dynamic modulus test machine used on asphalt concrete material. The AMPT dynamic modulus test has as an advantage in that loading and temperature regimes based on real pavement conditions can be rationally simulated and directly applied to the test samples. As such, the dynamic moduli of a cement-stabilized base course material can be obtained under different temperature and loading rates. Moreover, the effects of the dynamic strain range, cement content, and curing duration on the dynamic responses of a cement-stabilized base course material may also be examined. Cement-stabilized base course materials of 4 %, 5 %, and 6 % cement contents (by mass) were used as the study materials. The findings of this study indicate that curing durations and cement contents significantly influence the dynamic modulus values of cement-stabilized base course materials. However, the dynamic modulus is insignificantly affected by the changes in temperature and loading rates within a specific range of testing conditions in this study. The test results also reveal that cement-stabilized base course materials under examination behave in the manner of an elastic material when subjected to an axial compressive deformation of 45-105 ?strains. This is because of the dynamic modulus having no impact upon changes in the dynamic strain ranges or on the magnitudes of cyclic loads. Moreover, the dynamic moduli from this study were found to be much higher than the elastic moduli suggested by previous studies. However, the flexural moduli, which are derived from standard flexural tests, demonstrated close values to those of the dynamic moduli obtained in this study. In the study, the dynamic modulus of cement-stabilized base course materials, derived from the dynamic modulus using AMPT, could more reasonably embrace the dynamic responses of a material under traffic-loading conditions. This leads to a somewhat more reliable modulus input for the cement-stabilized base course materials used in a rational pavement design and analysis method.

The results of a round-robin testing study are presented for measurements of dynamic Young's modulus in two nickel-based alloys. The Interlaboratory Testing Program involved six types of apparatus, six different organizations, and specimens from a well-documented source. All the techniques yielded values of dynamic Young's modulus that agreed within 1.6% of each other. For Inconel alloy 600 the dynamic modulus was 213.5 GPa with a standard deviation of 3.6 GPa; for Incoloy alloy 907 the corresponding values were 158.6 and 2.2 GPa, respectively. No significant effect of frequency over the range 780 Hz to 15 MHz was found.

The dynamic elastic moduli of 40 metals and ALLOYS OF ENGINEERING INTEREST HAVE BEEN DETERMINED AT ROOM AND ELEVATED TEMPERATURES. Modulus determinations were based upon a relation between the speed of sound in a material and its elastic modulus. A specimen of the material was excited electrostatically and its resonant frequency determined. Knowing the geometry of the specimen, the dynamic elastic modulus was calculated. Room temperature comparisons of dynamic with static moduli were made in most instances using material from the same bar. The results of dynamic elastic modulus determinations are graphically presented.

Dynamic Mechanical Analysis (DMA) is a powerful technique for understanding the viscoelastic properties of materials. It has become a powerful tool for chemists, polymer and material scientists, and engineers. Despite this, it often remains underutilized in the modern laboratory. Because of its high sensitivity to the presence of the glass transition, many users limit it to detecting glass transitions that can’t be seen by differential scanning calorimetry (DSC). This book presents a practical and straightforward approach to understanding how DMA works and what it measures. Starting with the concepts of stress and strain, the text takes the reader through stress–strain, creep, and thermomechanical analysis. DMA is discussed as both the instrument and fixtures as well as the techniques for measuring both thermoplastic and thermosetting behavior. This edition offers expanded chapters on these areas as well as frequency scanning and other application areas. To help the reader grasp the material, study questions have also been added. Endnotes have been expanded and updated. Features Reflects the latest DMA research and technical advances Includes case studies to demonstrate the use of DMA over a range of industrial problems Includes numerous references to help those with limited materials engineering background Demonstrates the power of DMA as a laboratory tool for analysis and testing

Dynamic modulus measurements are used to study precipitation rates in 2024 Al alloy. The results are discussed in terms of the effect of structural changes on the elastic modulus as well as the kinetics of precipitation at various stages of the age-hardening process. Activation energies were determined for aging in the temperature ranges from room (77 F) to 130 F, and 375 F to 425 F. A value of 20.7 kcal/gm mole was obtained for the lower temperature range, and 23 kcal/gm mole for the higher temperatures. The data indicate that modulus changes are primarily influenced by the structure of the second phase, however, some evidence of strain energy effects are indicated. (Author)