摘要:

The objective of this work is to represent general nonlinear viscoelasticity by a model based on a modified two‐network theory. As a basic problem we examine Neubert and Saunders' data (1958) on the permanent set of crosslinked natural rubber samples after heating in a state of pure shear or simple extension. It is evident that the preferred configuration changes with time of heating. Our approach is to associate the preferred configuration with an internal measure of length in an initially isotropic material which becomes anisotropic after heating in a deformed state. Using Ericksen and Rivlin's work (1954) on anisotropic materials and a strain energy function which reduces for isotropic materials to Rivlin and Saunders' function (1951), we show an excellent consistency with the Neubert and Saunders' data. We also show consistency with some more recent data due to Djiauw and Gent (1973).

ISSN:0148-6055    

DOI:10.1122/1.549416

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

摘要:

A new type of viscometer is described, whose basic principle is the measurement of the damping of a fluid on a small resonant element. The major advantages of this instrument are that only small samples are required for analysis and that rapid cyclical measurements are possible. The viscometer can be used with Newtonian and non‐Newtonian fluids. In the present paper a theoretical analysis for a Newtonian fluid only is given. The theory is shown to predict the measured damping characteristics well for a number of test fluids.

ISSN:0148-6055    

DOI:10.1122/1.549417

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

摘要:

A strain energy density function has been developed for compressible rubber‐like materials. Its usefulness is demonstrated on hand of published data on the volume dilatation of natural rubber in simple tension.

ISSN:0148-6055    

DOI:10.1122/1.549418

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

摘要:

The flow behavior of 50 and 70 vol% transparent 2‐μm emulsions of amyl acetate in aqueous glycerol is described. The systems exhibited shear thinning behavior as well as large normal stress differences, the latter an order of magnitude greater than the tangential shear stresses. Particle motions were studied in 100‐μm tubes at mean flow rates from 40 to1500 μm sec−1using 2‐μm resin tracer spheres. The velocity profiles were blunted at all flow rates and at both concentrations with a region of apparent plug flow in the tube center whose radiusRedecreased with increasing flow rate and decreasing concentration. Large radial displacements of tracer spheres were observed atR>Re,and even whenR

ISSN:0148-6055    

DOI:10.1122/1.549431

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

摘要:

The response of a “rubbery” polymer, Dow Corning Silastic J Mold Making Silicone Rubber, to high‐amplitude, short‐duration loading is studied using acoustic waves and high‐amplitude stress waves. The acoustic experiments measured the phase velocity of a 1 MHz wave over a temperature range of −30°C to +65°C. These measurements were used to deduce the zero‐strain slope of the instantaneous and equilibrium stress‐strain curves for this material. Flyer‐plate impact experiments were used to study the high‐amplitude response. Two instrumentation techniques were used in this phase of the study. The first employed a quartz gauge in the “direct‐impact” configuration to obtain information about the equilibrium stress‐strain curve. The second employed velocity interferometer techniques to observed transmitted wave profiles and thereby obtain information about both the instantaneous and equilibrium curves. From these data, stress‐strain curves were determined for the Silastic J up to 0.8 GPa. Using this material characterization, the transmitted wave experiments were simulated using a one‐dimensional wave propagation code. The results of the calculations compare favorably with the transmitted wave profiles observed in the actual experiments.

ISSN:0148-6055    

DOI:10.1122/1.549432

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

摘要:

This analysis, using existing basic hydro‐dynamic theory for the entrance conditions into slits, has resulted in easily provable equations in this approximation, valid for Newtonian liquids without the complication of inertia (Reynolds number). This assumption is proved to be valid for the flows discussed. Furthermore, the limits of the existing theory are delineated, especially the area of transition from the converging to the parallel slit flow. This inaccessible range can be elucidated by direct experiments or by numerical methods with computers. This paper is the introduction to a series of experimental investigations which further analyze the flow conditions of Newtonian or viscoelastic liquids.

ISSN:0148-6055    

DOI:10.1122/1.549419

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

摘要:

This paper is concerned with the stress pulses emitted when glass specimens fracture under various types of loading. In particular, the pulses emitted under the following conditions are dealt with in detail: (a) fractures produced by Hertzian impacts; (b) fractures produced in rods under conditions of pure tension; (c) fractures produced in rods by ‘Hopkinson’ spalling; and (d) fractures produced in rods under conditions of pure bending. The information which these emitted pulses give with respect to the fracture process, and the interaction between the emitted pulses and the applied stress field are considered; the information which these results give with regard to the process of brittle fracture is also discussed.

ISSN:0148-6055    

DOI:10.1122/1.549420

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549433

出版商:The Society of Rheology    

年代:1976

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549434

出版商:The Society of Rheology    

年代:1976

数据来源: AIP