scholarly journals The Scheffe’s method in the study of mathematical model of the polymeric hydrogels composite structures optimization

2019 ◽  
Vol 6 (2) ◽  
pp. 258-267
Author(s):  
О. M. Grytsenko ◽  
◽  
P. Ya. Pukach ◽  
O. V. Suberlyak ◽  
V. S. Moravskyi ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Composite Structures ◽  
Polymeric Hydrogels

Finite Element Martensite Ratio Derivation on NiTi via Measurable Criteria of Strain Rate

2009 ◽  
Author(s):  
Abbas Amini ◽  
Hamid Mehdigholi ◽  
Mohammad Elahinia
Keyword(s):  
Mathematical Model ◽  
Strain Rate ◽  
Composite Structures ◽  
High Sensitivity ◽  
Smart Composite ◽  
Rate Dependency ◽  
Smart Composites ◽  
Measurable Amount ◽  
Macro Scale ◽  
Smart Composite Structures

The shape memory alloys (SMAs) and smart composites have a large use in high and low level industry, while a lot of research is being done in this field. The existence of smart composite structures is because of the advance mechanical benefits of the above materials. This work refers to dynamic and quasi static nonlinear explanation of these materials. After mathematical model consideration on the rate of strain, a model which is about martensite ratio of NiTi has been presented. This work has been done because of the high sensitivity of these materials to strain rate and use of visual and measurable engineering criteria to access other variables. As the martensite ratio is not engineering measurable amount, it needs to have macro scale property to measure this important nano scale criteria. Relative experiments are done to show the rate dependency of NiTi.

The Biot Model and Its Application in Viscoelastic Composite Structures

2007 ◽  
Vol 129 (5) ◽  
pp. 533-540 ◽  
Author(s):  
J. Zhang ◽  
G. T. Zheng
Keyword(s):  
Mathematical Model ◽  
Dynamic Behavior ◽  
Composite Structures ◽  
Optimization Method ◽  
Noise Attenuation ◽  
Viscoelastic Materials ◽  
Numerical Techniques ◽  
Viscoelastic Composite ◽  
Biot Model ◽  
Numerical Examples

Application of viscoelastic materials in vibration and noise attenuation of complicated machines and structures is becoming more and more popular. As a result, analytical and numerical techniques for viscoelastic composite structures have received a great deal of attention among researchers in recent years. Development of a mathematical model that can accurately describe the dynamic behavior of viscoelastic materials is an important topic of the research. This paper investigates the procedure of applying the Biot model to describe the dynamic behavior of viscoelastic materials. As a minioscillator model, the Biot model not only possesses the capability of its counterpart, the GHM (Golla-Hughes-McTavish) model, but also has a simpler form. Furthermore, by removing zero eigenvalues, the Biot model can provide a smaller-scale mathematical model than the GHM model. This procedure of dimension reduction is studied in detail here. An optimization method for determining the parameters of the Biot model is also investigated. With numerical examples, these merits, the computational efficiency, and the accuracy of the Biot model are illustrated and proved.

scholarly journals Dissipative properties of composite structures. 1. Statement of problem

2021 ◽  
Vol 4 (398) ◽  
pp. 24-34
Author(s):  
Boris Yartsev ◽  
◽  
Viktor Ryabov ◽  
Lyudmila Parshina ◽  
◽  
...  
Keyword(s):  
Mathematical Model ◽  
Composite Structures ◽  
Sandwich Plate ◽  
Complex Modulus ◽  
Viscoelastic Composite ◽  
Hamilton Variational Principle ◽  
Viscoelastic Polymer ◽  
Rigid Layer ◽  
Anisotropic Layers ◽  
Generalized Curves

Object and purpose of research. The object under study is a sandwich plate with two rigid anisotropic layers and a filler of soft isotropic viscoelastic polymer. Each rigid layer is an anisotropic structure formed by a finite number of orthotropic viscoelastic composite plies of arbitrary orientation. The purpose is to develop a mathematical model of sandwich plate. Materials and methods. The mathematical model of sandwich plate decaying oscillations is based on Hamilton variational principle, Bolotin’s theory of multilayer structures, improved theory of the first order plates (Reissner-Mindlin theory), complex modulus model and principle of elastic-viscoelastic correspondence in the linear theory of viscoelasticity. In description of physical relations for rigid layers the effects of oscillation frequencies and ambient temperature are considered as negligible, while for the soft viscoelastic polymer layer the temperaturefrequency relation of elastic-dissipative characteristics are taken into account based on experimentally obtained generalized curves. Main results. Minimization of the Hamilton functional makes it possible to reduce the problem of decaying oscillations of anisotropic sandwich plate to the algebraic problem of complex eigenvalues. As a specific case of the general problem, the equations of decaying longitudinal and transversal oscillations are obtained for the globally orthotropic sandwich rod by neglecting deformations of middle surfaces of rigid layers in one of the sandwich plate rigid layer axes directions. Conclusions. The paper will be followed by description of a numerical method used to solve the problem of decaying oscillations of anisotropic sandwich plate, estimations of its convergence and reliability are given, as well as the results of numerical experiments are presented.

scholarly journals Behaviour Inquiry of Floor Vibration on Composite Structures

2020 ◽  
Vol 9 (4) ◽  
pp. 1365-1370
Keyword(s):  
Mathematical Model ◽  
Finite Element Method ◽  
Finite Element ◽  
Composite Structures ◽  
Fem Analysis ◽  
Design Stage ◽  
Peak Acceleration ◽  
The Impact ◽  
Element Method ◽  
Slender Structures

In contemporary times, building construction requires light weight with slender structures rather than using conventional materials like concrete. Now a day's Structural Engineers concentrate much more on such slender structures with longer span. The impact of vibration due to human rhythmic activities like aerobics, jumping and dancing on these slender structures is a notable phenomenon. As per the various researchers contemplate, the floor vibrations annoyance not only affect the structure and also its impact over the occupants of the buildings in health affecting aspects. The aim of this paper is to analyse the vibration behavior of composite steel floor structuresunder gymnastic activities like jumping as human rhythmic activities by FEM analysis. The Finite Element Method analysis is done by using ANSYS software. From the Transient analysis of Finite Element method, the peak acceleration values are found out. These peak acceleration values are compared with the recommended values of IS 800-2007 and ISO 2631 – part II. The annoyance of such acceleration values under human rhythmic activities may induce vibration in terms of resonance; the natural frequency of the structural floor may coincide with any of the frequency of such activities. When resonance occurs, even fatigue failure of structures may happen. Hence it is essential for the structural Engineer to undergo the vibration analysis of composite floor structures during design stage itself.In order to check over such problems, in this paper as a novelty; a mathematical model is developed using SPSS software.This mathematical model is for peak acceleration values which helps the structural designer to analyse vibration problems under human rhythmic activities.

An Analysis Technique for Composite Structures Subject to Dynamic Loads

1971 ◽  
Vol 38 (1) ◽  
pp. 118-124 ◽  
Author(s):  
B. L. Edge ◽  
P. G. Mayer ◽  
G. A. Pierce
Keyword(s):  
Mathematical Model ◽  
Composite Structure ◽  
Composite Structures ◽  
Dynamic Loads ◽  
Normal Coordinates ◽  
Second Order Differential Equations ◽  
Space Frames ◽  
Analysis Technique ◽  
Dynamic Forcing ◽  
Distributed Forces

A technique has been developed to determine the response of space frames to dynamic forcing. The method is based on the normal mode approach. Essentially, each structural component is considered individually and then the system is coupled together. This procedure gives rise to a series of independent second-order differential equations, expressed in terms of the normal coordinates of the composite structure. It also represents the structure as a continuous mathematical model and allows the application of distributed forces which are allowed in turn to vary arbitrarily with time.

Microwave absorption performance enhancement using glass fiber-reinforced polymer nanocomposites containing dielectric fillers in X-band

2020 ◽  
pp. 096739112092350
Author(s):  
BVSRN Santhosi ◽  
K Ramji ◽  
NBR Mohan Rao
Keyword(s):  
Mathematical Model ◽  
Microwave Absorption ◽  
Layered Structure ◽  
Composite Structures ◽  
Radiation Absorption ◽  
Filler Materials ◽  
Multilayered Structures ◽  
Band Frequency ◽  
X Band ◽  
Absorption Performance

Microwave absorption properties of radar absorbing structures in X-band frequency have been investigated using carbon-based dielectric filler materials. These structures are composed of E-glass/epoxy laminates filled with various wt% (0–2.5 with an increment of 0.5) of graphene and multiwalled carbon nanotubes individually. Composite fabrication has been done using high-pressure resin transfer molding (HPRTM). The pertinent electromagnetic (EM) parameters of composite structures are measured using the waveguide measurement technique in X-band. From the results, a single-layered polymer composite with 2.5% graphene contains better absorption than others. Among multilayered structures, the 11-layered composite structure has shown the best absorption performance (reflection loss (RL) = −21 dB) which is equal to 99.9% of incident EM radiation absorption in X-band. It is found that the single-layered structure has shown ineffective absorption performance compared to the multilayered structure under low weight concentrations. Moreover, a mathematical model to predict RL of different combinations of multilayered structures based on EM wave theory is proposed for the calculation of optimum layer combination for minimizing time and money. The predictions of the mathematical model are validated for the 11-layered structure using experimentation.

scholarly journals THE DEVELOPMENT OF OPTICAL TESTING TECHNOLOGY OF PCM STRUCTURES BY FIBER-OPTIC SENSORS

2019 ◽  
pp. 26-35
Author(s):  
M. Yu. Fedotov ◽  
O. N. Budadin ◽  
S. O. Kozelskaya
Keyword(s):  
Mathematical Model ◽  
Composite Materials ◽  
Composite Structures ◽  
Fiber Optic ◽  
Sensitivity Coefficient ◽  
Fiber Optic Sensors ◽  
Destructive Testing ◽  
Testing Technology ◽  
Non Destructive

The ways of development of optical control technology of polymer composite materials structures by fiber-optic sensors during production and operation are described and investigated. A mathematical model describing the process of PCM monitoring using fiber optic sensors based on fiber Bragg gratings, clarifying the parameters of a mathematical model by experimentally determining the sensitivity coefficient of fiber optic sensors integrated in PCM, makes it possible to reduce the error in measuring strain by 5 – 7 times. The interaction in the system fiber-optic sensors – PCM and found that the integration of fiber-optic sensors based on quartz fibers in PCM, there is a partial destruction of the protective acrylate shell, which leads to the effect of microslip, which does not significantly affect the quality of measurements and can be compensated for by calibration. The requirements for the placement of fiber-optic sensors in the PCM at the manufacturing stage, including the formation of the input / output zone are formulated. The technology of optical non-destructive testing of composite materials with fiber-optic sensors is described, taking into account the features of the interaction of fiber-optic sensors with composite structures.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

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