摘要:

The characteristics of fracture elements in which the activation criterion is either a critical stress and/or strain are described. Their possible effects on the properties of phenomenological rheological models are demonstrated in the case of simplified models subjected to hypothetical deformation, stress relaxation and creep tests. It is also shown that introduction of the double criterion to models could produce rheological response patterns, especially in creep, that are more consistent with those of real materials.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00336.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Whole cabbages were subjected to impact and quasi‐static compression, and it was observed that the main type of damage was cracking through the leaf layers. In static loading the cabbages withstood very high compression loads before major cracking began, with forces between 4000‐4500 N.On impact, cracking of cabbages occurred at drop heights of 0.25 m and greater. There is a very strong linear relationship between total leaf crack length and energy dissipated during the drop. The crack resistance of cabbage is described by both the slope of the crack length‐energy dissipative response and the intercept of the line on the energy axis.Three energy dissipative mechanisms operate during the compression loading of cabbages; energy is stored elastically to be recovered in rebound, energy is stored to be dissipated by crack propagation, and energy is dissipated by leaf movement. The energy dissipative mechanisms can be explained in terms of the structure of the whole cabbage and leaf tissue.Crack resistance is a useful property of cabbages. It may be used to evaluate cabbage varieties for texture and cabbage handling systems for d

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00337.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Small amplitude dynamic viscoelastic properties of apple butter, mustard, tub margarine, and mayonnaise are compared with their respective properties in steady shear flow in the range of shear rates and frequencies of 0.1‐100 sec−1using a Rheometrics Mechanical Spectrometer. Comparison of dynamic and steady viscosities shows that dynamic viscosities (η*) are much larger than steady viscosities (η). Consequently the Cox‐Merz rule is not obeyed. Moreover the obvious nonlinearity suggests that shift‐factor type relationships are not obeyed either. The in‐phase (η') component of the dynamic viscosity shows similar behavior when compared to the steady viscosity (η).Comparison of G′/ω2and Ψ1also suggests that any of the results predicted by classical theories of viscoelasticity are not obeyed. G'/ω2is always much larger than Ψ1and the relationship between these two material fun

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00338.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Progels formed from aqueous dispersions of an imitation mozzarella cheese containing soy protein isolate, gelatin, fat and GFS gum (mixture of xanthan, guar and locust bean gums) at a total solids of 8% w/v exhibited pseudoplastic behavior. The data could be fitted to the power law equation for shear rates above 100 s−1. Below this shear rate, deviations from the model were observed such that the experimental apparent viscosity (va) was greater than the predicted vavalues. At 25deg;C, the progel's power law consistency coefficient (K) and vaincreased with increasing gelatin content and/or decreasing soy isolate content while the power law index (n) decreased. The reverse occurred when measurements were made at 40, 60 and 80deg;C. Soft gels formed when the progels were aged for 24 h at 4deg;C. Texture profile analysis and electron micrographs of the gels further emphasized the role of individual components in structural integrity and molecular interaction

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00339.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The rheological behavior of four types of tofu was evaluated through compressive stress‐strain relationships, relaxation parameters, and percent recoverable work at different strains. It is shown that tofu's deformability mode, like that of sponges, is regulated by both the solid matrix properties and internal hydrostatic pressure. Because the latter is strongly affected by the specimen geometry and the deformation rate, the dependency of mechanical parameters on these factors should be considered as an inherent characteristic of tofu's textur

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00340.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Granny Smith apple specimens were subjected to tensile loading at three deformation rates, 20, 50 and 100 mmXmin−1. Specimens were loaded either to failure or subjected to a load cycle less than required to cause fracture. The mode of failure observed was a sudden crack across the entire specimen perpendicular to the applied force. Unbroken specimens demonstrated considerable hysteresis losses during loading and unloading.Apparent and real fracture resistance values were calculated from the energy dissipated during cracking and crack surface area. Apparent fracture resistance varied from 258‐300 Jm−2, depending on deformation rate, and real fracture resistance was approximately constant at 200 Jm−2. The hysteresis ratio varied from 0.13‐0.4, depending on deformation rate, and this change in hysteresis losses explained the decrease in failure stress and failure deformation as deformation rate increased.It is postulated that fracture resistance, or the resistance to cracking is a useful tensile property of app

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00341.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AVI Food Products Formulary Series Vol. 4. Fabricated Foods.M.J. Inglett and G.E. Inglett, eds.Colloids in Foods.E. Dickinson and G. StainsbyFood Texture and Viscosity.M.C. BourneProgress and Trends in Rheology.H. Giesekus, K. Kirschke and J. Schurz, eds.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1983.tb00342.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY