Ontological Cross-Reducibility of Failure Theories for Composite Materials

Author(s):  
J. G. Michopoulos ◽  
A. P. Iliopoulos

Failure criteria have a significant role in the design of composite structural systems. Often the questions of “which criterion is more physical” and “which criterion is the best” create uncertainty in the design decision making process. To underline the ill-posed nature of both of these questions in the present paper we are describing the initial steps of an effort to address two ontological characteristics of failure criteria as they are applicable to composite materials applications. The first characteristic is the non-objective nature of failure criteria and an informal description is provided. The second characteristic is an ontologically based cross-reducibility between criteria. To underline more formally this characteristic we utilize an ontology-based framework to clarify “how a criterion relates with another” in terms of its main semantic attributes. The non-physical nature of a theory is exposed when it is evaluated from the semantic view of a systemic perspective. The human role on the formation of any failure criterion is shown to have a foundationally subjective character, thus rendering the corresponding criterion as non-objective. In the context of the second effort, the creation of classification ontology in terms of the semantic projections of failure criteria in their structural heritage and usage is created. The common attributes of failure criteria are utilized to identify the bases of the attribute space that they can be ontologically classified. Web ontology software is utilized to aid the ontological construction process and the visual interpretation of the ontological context. The derived cross-reducibility suggests that failure theories are special reductions of one another.

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Mohamed Mostafa Yousef Bassyouny Elshabasy

The classical failure criteria are phenomenological theories as they ignore the actual failure mechanism and do not concentrate on the microscopic events of failure. The main objective of the current investigation is to modify the classical failure theories to comprise the essential failure mechanism (interfacial shear failure) in the thin-layered woven-roving composite materials. An interfacial shear correction factor (MH6) is introduced into the nondimensional shear terms in the studied classical failure criteria. Thus the validity of applying these theories to the investigated material will be augmented. The experimental part of the current study is conducted on thin-layered circular specimens. The specimens are fabricated from two plies of fiber E-glass woven-roving fabric reinforced with polyester. The fabrics are laid to have [±45°] or [0°, 90°] fiber orientation. The specimens used are plain, where no macroscopic sources of stress concentration exist or having circular notches of five, seven, or nine mm radii. The specimens are subjected to low cycle completely reversed fatigue bending loading where the S-N and the R.D.-N curves are plotted for each group of specimens.


2021 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Aleksander Muc

The main goal of building composite materials and structures is to provide appropriate a priori controlled physico-chemical properties. For this purpose, a strengthening is introduced that can bear loads higher than those borne by isotropic materials, improve creep resistance, etc. Composite materials can be designed in a different fashion to meet specific properties requirements.Nevertheless, it is necessary to be careful about the orientation, placement and sizes of different types of reinforcement. These issues should be solved by optimization, which, however, requires the construction of appropriate models. In the present paper we intend to discuss formulations of kinematic and constitutive relations and the possible application of homogenization methods. Then, 2D relations for multilayered composite plates and cylindrical shells are derived with the use of the Euler–Lagrange equations, through the application of the symbolic package Mathematica. The introduced form of the First-Ply-Failure criteria demonstrates the non-uniqueness in solutions and complications in searching for the global macroscopic optimal solutions. The information presented to readers is enriched by adding selected review papers, surveys and monographs in the area of composite structures.


Author(s):  
Ramesh Talreja

Structural integrity of composite materials is governed by failure mechanisms that initiate at the scale of the microstructure. The local stress fields evolve with the progression of the failure mechanisms. Within the full span from initiation to criticality of the failure mechanisms, the governing length scales in a fibre-reinforced composite change from the fibre size to the characteristic fibre-architecture sizes, and eventually to a structural size, depending on the composite configuration and structural geometry as well as the imposed loading environment. Thus, a physical modelling of failure in composites must necessarily be of multi-scale nature, although not always with the same hierarchy for each failure mode. With this background, the paper examines the currently available main composite failure theories to assess their ability to capture the essential features of failure. A case is made for an alternative in the form of physical modelling and its skeleton is constructed based on physical observations and systematic analysis of the basic failure modes and associated stress fields and energy balances. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.


Author(s):  
إدريس التركاوي

للكائنات في تأملات النورسي وظيفة موسيقية جمالية في الكون، تتشكَّل من حركاتها المادية وتسبيحاتها الروحية، في دلالة ازدواجية مركبة تأبى التفكُّك؛ ما يستفز التدبر في الإنسان، ويدفعه إلى إعادة قراءة الكون والكائنات؛ قراءة تراعى فيها الوحدة الكونية والقانون التعبدي المشترك الجامع بين طبيعة الشيء المادية ووظيفته التوحيدية المعنوية، وليس الاكتفاء بإحداهما. Nursi's reflections show that creatures have an aesthetic musical function which is composed of their physical movement and spiritual glorification, which comes in inseparable compound duality. This function provokes human contemplation that requires rereading the natural cosmos and creatures in such a way that takes into account the cosmos unity and the common worship law which bring together both the physical nature of things and their moral monotheistic function.  


Author(s):  
E. H. Irhirane ◽  
J. Echaabi ◽  
M. Hattabi ◽  
M. Aboussaleh ◽  
A. Saouab

2011 ◽  
Vol 467-469 ◽  
pp. 575-578 ◽  
Author(s):  
Zhen Qing Wang ◽  
Song Zhou ◽  
Jian Sheng Zhou ◽  
Xiao Yu Sun

Composite materials not only have good mechanical performances but also have excellent durability and ability to be formed into complex shape. So advanced composite materials are used extensively in ship industry. In the composite ship structure the T-joint is one of the common joint in practice. As the main load-bearing structure of ship, the mechanical and reliability designs of T-joint are the important aspects of the ship structure design. The traditional composite T-joint is bonded joint, and adhesive strength has obvious influence on the properties of T-joint. To improve the properties of composite T-joint, in this paper the bolted composite T-joint is chosen for studying. Finite element method is used to investigate the properties of bolted T-joint. The influences of bolt-clamping load and friction coefficient on the stress distribution of bolt-hole edge are investigated. Some conclusions can be used as references for the design of bolted composite T-joint.


2012 ◽  
Vol 430-432 ◽  
pp. 1155-1158
Author(s):  
Rong Jian Li ◽  
Wen Zheng ◽  
Jun Ding Liu ◽  
Tao Xie

The failure criteria in strength reduction FEM are not unified and often affected greatly by researcher’s experience and judgment, so it is necessary to discuss the applicability and the difference of some various criteria of instability of slope. According to the thought of visualization in real time computing, the corresponding visual program is developed based on some common failure criteria adopted simultaneity in the strength reduction FEM. Then, through the real-time visual interface, the comparisons of the common failure criteria are conducted. The results show that, the safety factor of a simple slope can be determined clearly from the inflection point of the computational curve based on the criterion of the characteristic nodal displacement and the criterion of equivalent plastic strain exceeding a certain value, by contrast, the safety factor which based on the criterion of the iteration non-convergence lag behind the others in the same condition.


1993 ◽  
Vol 15 (3) ◽  
pp. 41-48
Author(s):  
Tran Ich Thinh

The general invariant forms of failure criteria for anisotropic solids were studied and applied to orthotropic composite materials. when subjected to three-dimensional stress states with rotational symmetry. The Hill criterion and the Tsai and Wu criterion are special cases of these general forms.


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