Sonlu elemanlar metodu yardımıyla cam işleme prosesinin ısıl analizi
The Thermal analysis of glass forming process by finite elements method
- Tez No: 19290
- Danışmanlar: DOÇ.DR. TANER DERBENTLİ
- Tez Türü: Yüksek Lisans
- Konular: Makine Mühendisliği, Mechanical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1991
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 119
Özet
ÖZET Bugünün imkanlarıyla cam eşya üretimi hemen hemen tamamen otomatik makinalarda,çok yüksek kapasitelerde gerçekleştirilmektedir »Fakat cam endüstrisi ulaştığı bu noktada bile eskiden beri süregelen bir optimizasyon problemi ile karsı karşıyadır» Bu problem, minimum kalınlıkta iç ve dış basınçlara mukavim bir ürüne ulaşmaktır. Problemin anahtar noktası prosesten çok ürünün kendisinin optimizasyonudur »Çünkü bir cam mamulün ( sise» kavanoz gibi )mekanik dayanıklılığı en ince noktasına veya noktasal gerilmelere bağlı olduğuna göre, ideal üründe her noktasında aynı et kalınlığına (uniform) sahip bir ürün demektir» E
Özet (Çeviri)
SUMMARY : THE THERMAL ANALYSIS OF GLASS FORMING PROCESS by FINITE ELEMENTS METHOD R.Onur Gündüz The manufacturing process of glass forming items is done by almost fully automated mass production machines. Desipite the high rates of production, the engineers and researchers in this field are facing an optimisation problem» The problem can be expressed as follows 5 given the external shape of the final product as well as minimal requirements regarding its capacity n the product must resist internal pressure as well as external shocks. Clearly a key element in the problem is the optimiza tion of the design of the product itsel f »Since the mechanical strength of a bottle or jar is largely depen dent on its section of minimum thickness» the optimum design is a constant (uniform distributed) thickness container. Optimization of glass forming process consist of 3 main steps» i ) Preparing input data such as initial temperature distribution in mould » material properties » and other coefficients by utilizing.the most acurate and precise measurement techniques» Then verifiying the results obtained from theotrati- cai studies with the measurements taken from the empty mould and the final product» Briefly, the first step towards the full scale op timization -is to havE» high precision and high response time measurement techniques and equipments» VI İ 1ii ) In the second step the thermal side of the problem is defined and solved by employing a ppverful numerical method such as the Finite Elements Method» The aim of this step is to analyse the temperature distribution in the mould and glass and determine the amount of heat transferred from glass to mould then to the environment. This is also an optimisation study alone »Because if the cooling stage can be investigated some important parameters could be optimized such as cooling fins on mould, blowing air temperature and velocity and produc tion rate» By adjusting these parameters it can be possible tp avoid uneven cooling and reach higher production rates» iii ) To reach a full scale numerical model of glass forming process the mechanical simulation must also be included. Mechanical simulation is the challenging part of the problem. Because to know exactly how melted glass moves in mould and what happens when glass thouches the mould's wall is impossible. So important assumptions are required» In this part besides the thermal fields. the velocity field is determined.Then the thermal and mechani cal problems are coupled» Briefly stated the modelling of glass forming process is a non-linear problem in which the material is ' elasto- plastic and where thermal and mechanical features must be cosidered simultaneously» In the study a linear model of heat conduction in glass moulds is established by a finite element approach. This model can compute steady state and transient tempare- ture distribution in glass moulds under convection ' con stant temperature or costant heat flux boundary conditions. The object of this study is to determine the tempera ture variotions which occur at the glass and mould simun t aneous 1 y » In the glass forming 'operation the glass is in con tact with the metal surface of the mould for a certain period, reffered to as the“contact time”during which heat flows to the metal »The glass is then removed and the mould is allowed to cool during the rest of the cycle and this is reffered to as“Seperation Time”. IXThe cycle is charecterised by different. heat exchanges» 1) Heat Transfer at the interface between glass and mould during the contact time. 2) Heat transfer at the interface between air and mould and between the mould surface and the ambient.by radiation and natural convection during the seperation time 3) Heat Transfer within the mould during the cycle. The contribution of, radiative transfer to the thermal distribution is neglected» To analyse the model. Finite Element. Method has been used. This method can briefly be explained as follows. The fundamental concept of the finite elements method is that »any continuous quantity »such as temperature, pressure or displacement can be approximated by a discrete model composed of a set of piecewise con tinuous functions defined over a finite number of subdomains» To apply the method the discrete model must be constructed.Discretization of the shape is done with these steps» 1) A finite numbers of points in the domain is idendified. These points are called as nodes» 2) The value of the continuous quantity at each node is denoted as a variable which is to be determined. 3) The domain is divided into a finite numbers of subdomains called elements. These elements are connected at common nodal points and collectively approximate the shape of the domain » 4) The continuous quantity is approximated over each element by a polynomial that is defined using the nodal values of the continuous quantity» As it is well known, this method has been developed to provide solutions to problems where an analytical or classical numerical approach is impossible» It may be ap plied to a wide variety of problems defined by quasi- harmonic partial differential' equations, such as stress analysis, fluid and thermal engineering etc »Its use is par ticularly interesting for problems involving complex geometries»The shape of elements as well as the analytical form of the sub-fields are standardised »The investigated field at any point thereby reduced to known functions of a limited number of parameters. namely values of the inves tigated parameters ( i »e temperature) in some particular points called nodes. The variational principle is then applied to the dis- cretized field in order to determine the set of nodal values that leads to the best approximation of the rea!l field. This leads to the solution of a system of ordinary algebraical equations. T he shape, the sise and the nodes number of the elements may be adapted to the problem to be solved. The computer program essentially calculates the coef ficients of the set of linear algebraic equations and then solves this system. The program can be divided into six different parts s 1 ) Data Input s The data to foe introduced are the number of constitutive materials and their respective thermal conductivity şand of the nodes located at the ver tices of these? elements and the co-ordinates of these nodes. Finally input data are introduced for boundary con ditions at the inner wall of the mould. 2 ) Computation of stiffness matrix and convection matrix. 3 ) Computation of the boundary conditions vectors for each node. 4 ) Matrices and boundary conditions vectors assembly, 5 ) Solution of the linear equations system in nodes- temperature. 6 ) Results output. The above described program may lead to two kinds of investigation s a ) The mould exists» its geometry is defined and the inner wall boundary conditions are fixed for a given production. The influence of the cooling parameters on the temperature distribution can then be evaluated. XIThe cycle is charecterised by different. heat exchanges» 1) Heat Transfer at the interface between glass and mould during the contact time. 2) Heat transfer at the interface between air and mould and between the mould surface and the ambient.by radiation and natural convection during the seperation time 3) Heat Transfer within the mould during the cycle. The contribution of, radiative transfer to the thermal distribution is neglected» To analyse the model. Finite Element. Method has been used. This method can briefly be explained as follows. The fundamental concept of the finite elements method is that »any continuous quantity »such as temperature, pressure or displacement can be approximated by a discrete model composed of a set of piecewise con tinuous functions defined over a finite number of subdomains» To apply the method the discrete model must be constructed.Discretization of the shape is done with these steps» 1) A finite numbers of points in the domain is idendified. These points are called as nodes» 2) The value of the continuous quantity at each node is denoted as a variable which is to be determined. 3) The domain is divided into a finite numbers of subdomains called elements. These elements are connected at common nodal points and collectively approximate the shape of the domain » 4) The continuous quantity is approximated over each element by a polynomial that is defined using the nodal values of the continuous quantity» As it is well known, this method has been developed to provide solutions to problems where an analytical or classical numerical approach is impossible» It may be ap plied to a wide variety of problems defined by quasi- harmonic partial differential' equations, such as stress analysis, fluid and thermal engineering etc »Its use is par ticularly interesting for problems involving complex geometries»
Benzer Tezler
- Sonlu elemanlar yöntemiyle sac parçalarının şekillendirilmesinde ağ yapılanması
Finite element mesh generation for sheet metal forming
FERİT FIRAT
Yüksek Lisans
Türkçe
2001
Makine Mühendisliğiİstanbul ÜniversitesiMakine Mühendisliği Ana Bilim Dalı
YRD. DOÇ. DR. FERHAT ÇELİK
- Failure analysis of pin-loaded composite plates
Pim yüklü kompozit plakalarda hasar analizi
ÖZGÜR AHISHALI
Yüksek Lisans
İngilizce
2006
Makine MühendisliğiDokuz Eylül ÜniversitesiMakine Mühendisliği Bölümü
PROF. DR. ONUR SAYMAN
- Stress analysis of pin-loaded composite laminates
Pimle yüklenmiş kompozit tabakalarda gerilme analizi
MEHMET ALTINHAN
- Spider camların düzleme dik yükleme halinde gerilme analizi
The behaviour of spider glass under out of plane loads
EREN KALAY
Yüksek Lisans
Türkçe
2017
Makine Mühendisliğiİstanbul Teknik ÜniversitesiMakine Mühendisliği Ana Bilim Dalı
YRD. DOÇ. DR. İSMAİL GERDEMELİ