کامپوزیت‎های زمینه سرامیکی بافته شده

Multiscale model of woven ceramic matrix composites

considering manufacturing induced damage

کامپوزیت‎های زمینه سرامیکی بافته شده با توجه به آسیب‎های ایجاد شده‎ی تولید

ABSTRACT

Multiscale models play an important role in capturing the nonlinear response of woven carbon fiber reinforced ceramic matrix composites. In plain weave carbon fiber/silicon carbide (C/SiC) composites, for example, when microcracks form in the as-produced parts due to the mismatch in thermal properties between constituents, a multiscale thermoelastic framework can be used to capture the initial damage state of these composites. In this paper, a micromechanics-based multiscale model coupled with a thermoelastic progressive damage model is developed to simulate the elastic and damage behavior of a plain weave C/SiC composite system under thermal and mechanical loading conditions. The multiscale model is able to accurately predict composite behavior and serves as a valuable tool in investigating the physics of damage initiation and progression, in addition to the evolution of effective composite elastic moduli caused by temperature change and damage. The matrix damage initiation and progression is investigated at various length scales and the effects are demonstrated on the global composite behavior.

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فرایند زینترینگ انفعالی و خواص ترموالکتریک کاربیدهای غنی از بور

Reactive sintering process and thermoelectric properties of

boron rich boron carbides

فرایند زینترینگ انفعالی و خواص ترموالکتریک کاربیدهای غنی از بور

ABSTRACT

Dense boron rich boron carbides were reactive sintered by hot pressing at 2050 °C using elementary boronsingle bondcarbon compositions with carbon contents of 9.1, 11.1, 13.3 and 18.8 at.%. The following material characteristics are presented: relative density, SEM images, EDX, X-ray diffraction and corresponding lattice parameters, Seebeck coefficient, electrical conductivity and thermoelectric power factor. Significant grain growth has been obtained with increasing boron content. A deeper understanding of the boron and carbon reaction and the overall sintering process is gained by thermal and chemical analysis in combination with X-ray diffraction. Additionally a thermal experiment with boron and carbon layers illustrates the solid state diffusion behaviour. The found results of boron carbide properties of this paper correspond with results by other authors. The aim is to correlate technological aspects of sintering procedure with material properties. This should help to improve the thermoelectric efficiency of boron carbide based materials.

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آموزش نرم افزار Sysweld شبیه سازی جوشکاری و عملیات حرارتی

آموزش نرم افزار Sysweld

 شبیه سازی جوشکاری و عملیات حرارتی

قوی ترین نرم افزار شبیه سازی جوشکاری

  عملیات حرارتی و اتصالات جوش  

نرم افزار SYSweld معروف ترین و پرکاربردترین نرم افزار شبیه سازی در صنعت جوشکاری و عملیات حرارتی می باشد . همانگونه که می دانید که نرم افزارهای شبیه سازی مهندسی نرم افزارهایی کاربرپسند نیستند و کاربر بایستی جهت استفاده ازین نرم افزارها تحت آموزش قرار بگیرد .

کامل ترین مجموعه آموزشی نرم افزار Sysweld بسته SysWeld ToolBox CD  بوده  که توسط کمپانی ESI آماده گردیده و گام به گام به آموزش این نرم افزار بهمراه حل مثال و راه حل ها می پردازد .

این مجموعه سر فصل های مختلف را از آشنایی عمومی تا حل مثال های پیشرفته در انواع روش های جوشکاری و انواع قطعات و جنس های مختلف و عملیات حرارتی بهمراه اصل فایل پروژه را شامل می شود .

اگر شما هم مایلید تا با این نرم افزار حرفه ای کار کنید صمیمانه توصیه می کنیم ازین بسته آموزشی استفاده کنید .

توضیحات بیشتر در ادامه مطلب ...  

مواد الکتروکرومیک

Electrochromic Materials

مواد الکتروکرومیک

ABSTRACT

 A set of materials exhibit electrochromic activity when constituted as a thin film structure whose coloration can be changed reversibly by electrical charging and discharging . there are two types of such electrochromic materials . The first type is uncolored when unpowered and changes to a colored state when a voltage is applied and returns to its uncolored state when the voltage is removed . In the second type an opposite voltage is required to be applied for bleaching ( or decoloration ) .The degree of coloration is a direct visual indication of the state of charing present in the material .

مواد ابر رسانا

Superconducting Materials

مواد ابر رسانا

ABSTRACT

The phenomenon of superconductivity came to be known in 1911 by observing that a capillary column of mercury immersed in a liquid helium bath woud show an abrupt reduction in resistance and at 4.2 K it became impossible to measure the low resistance exhibited by the column with the then available measurement techniques . It was concluded that below a critical temperature (T_c) the mercury had passed into a new state . Subsequent studies on superconduction were pursued with tin and lead as candidate materials and it was discovered that a critical current density (J_c) is carried by a superconduction sample before it returns to its normal ( metallic ) state .

مقدمه الزامات مهندسی برای مواد کامپوزیتی صنعت هوافضا

Introduction: engineering
requirements for aerospace
composite materials

مقدمه الزامات مهندسی برای مواد کامپوزیتی صنعت هوافضا 

ABSTRACT

Composite materials have gained popularity (despite their generally high cost) in high performance products that need to be lightweight, yet strong enough to take high loads such as aerospace structures (tails, wings and fuselages), boat construction, bicycle frames and racing car bodies. Other uses include storage tanks and fishing rods. Natural composites (wood and fabrics) have found applications in aircraft from the first flight of the Wright Brothers’ Flyer 1, in North Carolina on December 17, 1903, to the plethora of uses now enjoyed by man-made (engineered) composite materials on both military and civil aircraft, in addition to more exotic applications on unmanned aerial vehicles (UAVs), space launchers and satellites. Their adoption as a major contribution to aircraft structures followed on from the discovery of carbon fibre at the Royal Aircraft Establishment at Farnborough, UK, in 1964.

وضعیت صنعت در کنترل آخال ها در طی ریخته گری شمش فولادی

State of the Art in the Control of Inclusions during Steel
Ingot Casting

وضعیت صنعت در کنترل آخال ها در طی ریخته گری شمش فولادی

ABSTRACT

This article extensively reviews published research on inclusions in ingot steel and defects on ingot products, methods to measure and detect inclusions in steel, the causes of exogenous inclusions, and the transport and entrapment of inclusions during fluid flow, segregation, and solidification of steel cast in ingot molds. Exogenous inclusions in ingots originate mainly from reoxidation of the molten steel, slag entrapment, and lining erosion, which are detailed in this article. The measures to prevent the formation of exogenous inclusions and improve their removal are provided, which are very useful for the clean steel production of ingot industries.

مواد نیمه رسانا

Semiconducting Materials

مواد نیمه رسانا

ABSTRACT

Semiconductors are materials which have resistivities between the extremes of metallic conductors and insulators. A typical scale of conductivity of materials is depicted in Figure 10.1 . Semiconductors lie approximately between conductors ( with σ > 10⁵ siemen/meter ) and insulators (with σ < 10^-10 siemen/meter ) . Semiconductors are materials with filled valence bands and have a small forbidden energy gap between the upper-filled band and the overlapping vacant energy band . The electric conduction in Semiconductors is effected by two types of charge carriers namely . electrons ( negative charge carriers ) and holes ( positive charge carriers ) .

مواد فروالکتریک

Ferroelectric Materials

مواد فروالکتریک

ABSTRACT

Ferroelectric materials are typically nonlinear dielectrics with the following characteristics :

• They exhibit distinct dependency of permittivity on the intensity of an applied electric field
• The dielectric displacement versus applied electric field follows hysteresis loop characteristics
• The dielectric constant of these materials are invariably very high , on the order of thousands to tens of thousands .
• The dielectric parameters are pronouncedly dependent on temperature and the ferroelectric properities are observed only within a definite range of temperature
• There is presence of spontaneous dielectric polarization in the absence of external electric field And this polarization can be switched in direction by applying an electric field

مواد الکترولیت جامد

Solid Electrolytic Materials

مواد الکترولیت جامد

ABSTRACT

Also known as superionic conductors solid electrolytes are ionic materials which exhibit high electrical conductivity ( in comparsion whit liquid electrolytes ) above a certain critical temperature . They are also termed as fast-ion conductors . A solid electrolytes has the following characteristics .

• It is crystalline with ionic bonding
• Its electrical conductivity ( over a specified temperature is high ( 10-10-2 siemen/meter ) .
• Its principal charge carriers are ions . Hence , the fractional contribution of the ionic conductivity to the total conductivity ( termed as ionic transference number ) is almost equal to one .
• Its electronic conductivity is small . The corresponding electronic transference number is less than 10-4