Fracture of High Polymers

1967 ◽  
Vol 40 (4) ◽  
pp. 1036-1048 ◽  
Author(s):  
W. Retting
Keyword(s):  
Physics Of Failure ◽  
Elongation At Break ◽  
Failure Theory ◽  
Experimental Parameters ◽  
Failure Properties ◽  
Tearing Energy ◽  
Viscoelastic Substances ◽  
Breaking Energy ◽  
Macroscopic Failure ◽  
High Polymers

Abstract General considerations of the physics of failure of high polymeric substances were reviewed using the example of one dimensional testing. It is shown that classical failure theory can be applied only with difficulty to viscoelastic substances. Relations between macroscopic failure properties and the parameters of test are reviewed. Several recent investigations have shown a direct relation between relaxation time spectra of high polymers and breaking energy, tensile strength, and elongation at break through their dependence on time and temperature. Finally, the relation between microscopic failure properties and experimental parameters are discussed. The processes occurring at the tip of the failure are determined by relaxation mechanisms just as are the processes which lead to sites of failure in the macroscopic specimen. These are illustrated by recent work in which the specific tearing energy is determined as a function of time and temperature of tearing. From all of the work referred to here, it follows that the very complicated relations at fracture of high polymers are essentially determined by their mechanism of molecular motion in a way analogous to other mechanical properties and are therefore determined by their molecular structure.

A Fracture Theory for Brittle Anisotropic Materials

1974 ◽  
Vol 96 (2) ◽  
pp. 91-96 ◽  
Author(s):  
T. G. Priddy
Keyword(s):  
Orthotropic Materials ◽  
Necessary Condition ◽  
Material Strength ◽  
Interaction Coefficients ◽  
Cubic Equation ◽  
Simple Cubic ◽  
Failure Theory ◽  
Tension And Compression ◽  
Fracture Theory ◽  
Macroscopic Failure

This paper outlines the development of a general macroscopic failure theory. The result is a relatively simple cubic equation where interaction coefficients for tension-tension and compression-compression strengths may be defined separately. Approximations for biaxial and triaxial normal stress interactions are included to reduce the number of experimental data to nine for brittle three-dimensionally orthotropic materials and to two for brittle isotropic materials. A necessary condition that the theory closely describe brittle isotropic material strength is satisfied for a comprehensive set of cast iron biaxial strength data. The surface is graphically illustrated for various materials.

Failure Mechanics—Part II: The Central and Decisive Role of Graphene in Defining the Elastic and Failure Properties for all Isotropic Materials

2014 ◽  
Vol 81 (11) ◽  
Author(s):  
Richard M. Christensen
Keyword(s):  
Elasticity Theory ◽  
Three Dimensional ◽  
Decisive Role ◽  
Common Belief ◽  
Failure Mechanics ◽  
Isotropic Materials ◽  
Failure Theory ◽  
Failure Properties ◽  
2D Elasticity

Continuing from Part I (Christensen, 2014, “Failure Mechanics—Part I: The Coordination Between Elasticity Theory and Failure Theory for all Isotropic Materials,” ASME J. Appl. Mech., 81(8), p. 081001), the relationship between elastic energy and failure specification is further developed. Part I established the coordination of failure theory with elasticity theory, but subject to one overriding assumption: that the values of the involved Poisson's ratios always be non-negative. The present work derives the physical proof that, contrary to fairly common belief, Poisson's ratio must always be non-negative. It can never be negative for homogeneous and isotropic materials. This is accomplished by first probing the reduced two-dimensional (2D) elasticity problem appropriate to graphene, then generalizing to three-dimensional (3D) conditions. The nanomechanics analysis of graphene provides the key to the entire development. Other aspects of failure theory are also examined and concluded positively. Failure theory as unified with elasticity theory is thus completed, finalized, and fundamentally validated.

Failure Theory/Failure Criteria for Fiber Composite Laminates

2016 ◽  
Vol 84 (2) ◽  
Author(s):  
Richard M. Christensen ◽  
Kuldeep Lonkar
Keyword(s):  
Composite Laminates ◽  
Fiber Composite ◽  
Failure Criteria ◽  
Fiber Composites ◽  
Failure Envelope ◽  
Related Matter ◽  
Failure Theory ◽  
Testing Data ◽  
Failure Properties ◽  
Theory Failure

Failure criteria are derived for the case of a quasi-isotropic laminate and for the more general case of orthotropic laminates. The former requires two calibrating failure properties obtained directly from laminate testing and the latter requires five standard experimental measurements for its calibration. Then the quasi-isotropic failure theory is taken much further, also admitting full calibration by only the two composites tow failure properties, the associated unidirectional tensile, and compressive strengths. The theoretically predicted failure envelope for the quasi-isotropic laminate is favorably compared with some comprehensive testing data. As a related matter, the general failure criteria for unidirectional fiber composites are also reviewed.

The Failure Theory for Isotropic Materials: Proof and Completion

2019 ◽  
Vol 87 (5) ◽  
Author(s):  
Richard M. Christensen
Keyword(s):  
Brittle Failure ◽  
Ductile Failure ◽  
Isotropic Materials ◽  
Failure Theory ◽  
History Of ◽  
Failure Properties ◽  
Complete Form ◽  
The Many ◽  
Entire Theory

Abstract This work represents the completion of the many developments in recent years on failure theory for homogeneous and isotropic materials. Presented here is the resulting failure formalism in final and technically complete form. Significant further results are also given for the verification of the failure formalism. The scope of this paper goes from the history of misguided failure theory investigations right up to the present final tested forms ready for applications. For every predicted failure level in terms of the stresses, there is an accompanying ductility level. This ranges from brittle failure up to fully ductile failure. The entire theory is calibrated by only two specified parameters (failure properties). Nothing else is needed. The seemingly interminable, actually centuries long search for the missing theory of failure has finally been brought to a resolute and successful conclusion.

Determination of Combined and Second Order Factor Effects for Simultaneous Optimization of Physical and Mechanical Properties of NR/BR Blend System

2014 ◽  
Vol 42 (4) ◽  
pp. 290-304
Author(s):  
Rajarajan Aiyengar ◽  
Jyoti Divecha
Keyword(s):  
Physical And Mechanical Properties ◽  
Second Order ◽  
Simultaneous Optimization ◽  
Order Effects ◽  
Elongation At Break ◽  
Five Factors ◽  
Rubber Compounds ◽  
Polybutadiene Rubber ◽  
Contour Plots

ABSTRACT The blends of natural rubber (NR), polybutadiene rubber (BR), and other forms of rubbers are widely used for enhancing the mechanical and physical properties of rubber compounds. Lots of work has been done in conditioning and mixing of NR/BR blends to improve the properties of its rubber compounds and end products such as tire tread. This article employs response surface methodology designed experiments in five factors; high abrasion furnace carbon black (N 330), aromatic oil, NR/BR ratio, sulfur, and N-oxydiethylene-2-benzothiazole sulfenamide for determination of combined and second order effects of the significant factors leading to simultaneous optimization of the NR/BR blend system. One of the overall optimum of eight properties existed at carbon 44 phr, oil 6.1 phr, NR/BR 78/22 phr with the following values of properties: tensile strength (22 MPa), elongation at break (528%), tear resistance (30 kg/mm), rebound resilience (67%), moderate hardness (68 International rubber hardness degrees) with low heat buildup (17 °C), permanent set (12%), and abrasion loss (57 mm3). More optimum combinations can easily be determined from the NR/BR blend system models contour plots.

The use of insoluble matter of Moroccan oil shale for removal of dyes from aqueous solution

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methylene Blue ◽  
Oil Shale ◽  
Heating Temperature ◽  
Blue Dye ◽  
Adsorption Capacities ◽  
Experimental Parameters ◽  
Initial Ph ◽  
New Material ◽  
Activating Agent ◽  
Moderate Cost

The study aims to use an adsorbent natural based of Moroccan oil shale of Timahdit area (Y layer) in a physical-chemical adsorption process for treating industrial discharges colorful. The used adsorbent is the insoluble party of the sub-critical extraction of decarbonized oil shale of Timahdit. The tests performed on the methylene blue (MB), showed a strong elimination in the first 10 minutes. The influences of various experimental parameters were studied: mass ratio of adsorbent, time and temperature of thermal treatment, contact time, pH of MB and heating temperature of solution on the parameters of material were studied. The experimental results have shown that the adsorption of methylene blue dye by the adsorbent is more than 90% at initial pH a range 6-7 at room temperature for 30 minutes. The process is simple and the adsorbent produced is a new material with interesting adsorption capacities of moderate cost which does not require an activating agent and can be used as industrial adsorbent for the decontamination of effluents containing organic pollutants.

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