Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are us... more Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are usually required if surface turbulence is to be eliminated. Latest research has demonstrated, that for every liquid metal there is critical velocity above which the surface will fold over and entrain itself in the bulk of the metal. Therefore the strength properties the aluminium castings are largely determined by microstructural defects, particularly pores and oxide films which are created by surface turbulence. The purpose of this paper is to investigate tensile properties and microstructure of aluminium alloy in a casted state two different designs of gating system. The first is the usual bottom gating system and the second is novel design of gating system named a vortex-gate introduced by Campbell [1]. The results of the mechanical tests revealed that there is a small improvement in ultimate tensile strength for vortex-gate design of pouring system. The oxide film defects were observed in microstructure of a sample taken from poured casting by using the bottom gated system.
Cartridge brass is represented by deep-drawing bra ss marked as Ms70 (CuZn30 according to DIN sta... more Cartridge brass is represented by deep-drawing bra ss marked as Ms70 (CuZn30 according to DIN standards). Classical brass cartri dge manufacturing technology uses rolled brass sheets as input semiproduct. Continuous press ure on manufacturing costs caused technological change which has introduced the manufacture of brass cartridges from bars. Brass bars are manufactured by hot extrusion pressing and subsequent cold drawing. The hot extrusion
Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are us... more Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are usually required if surface turbulence is to be eliminated. Latest research has demonstrated, that for every liquid metal there is critical velocity above which the surface will fold over and entrain itself in the bulk of the metal. Therefore the strength properties the aluminium castings are largely determined by microstructural defects, particularly pores and oxide films which are created by surface turbulence. The purpose of this paper is to investigate tensile properties and microstructure of aluminium alloy in a casted state two different designs of gating system. The first is the usual bottom gating system and the second is novel design of gating system named a vortex-gate introduced by Campbell [1]. The results of the mechanical tests revealed that there is a small improvement in ultimate tensile strength for vortex-gate design of pouring system. The oxide film defects were observed...
Abstrakt V príspevku autori opisujú viaceré technické riešenia zvyšovania ivotnosti kovacích záp... more Abstrakt V príspevku autori opisujú viaceré technické riešenia zvyšovania ivotnosti kovacích zápustiek, ktoré sú realizované vo výrobnej praxi. Poukazujú na rozdielnosti v prístupoch pri aplikácii tej ktorej metódy ovplyvovania ivotnosti kovacích nástrojov. V príspevku sú uvedené konkrétne výsledky zo sledovania ivotnosti vytypovaných ková �skych zápustiek pracujúcich za tepla. Sledovanie ivotnosti sa uskutonilo priamo vo výrobných podmienkach. V príspevku sú zhrnuté výsledky z piatich technologických riešení zvyšovania ivotnosti ková �skych zápustiek, priom kadé z riešení má svoje špecifiká. Pred zápustkovým kovaním je dôleité komplexné posúdenie faktorov, ktoré do technologického procesu vstupujú, teda stroj, výkovok, nástroj. Z opísaných technologických riešení je moné potom navrhnú � práve také, ktorým je moné zásadne pozitívne ovplyvni� ivotnosdrahého kovacieho nástroja, ktorým kovacia zápustka je. ivotnoszápustky zásadne ovplyvuje správny výber materiálu. Z tohto po...
X-Ray and Neutron Structure Analysis in Materials Science, 1989
An analysis can be regarded as a process of changing the degree of uncertainty with respect to th... more An analysis can be regarded as a process of changing the degree of uncertainty with respect to the unknown values. The goal of an analysis is then to gain a maximum decrease of uncertainty. This implies that the decrease of uncertainty also describes the inadequacy of the analysis and may be considered as a measure for the amount of information obtained1,2,3. X-ray diffraction is a very powerful analytical technique since it enables to obtain a lot of information on the structure of matter: its phase composition, molecular structure, and real structure. The information content of X-ray diffraction analytical techniques can further be extended when they are applied to the examination of processes.
High temperature plastic deformation of CuZn30 brass was investigated in the temperature range be... more High temperature plastic deformation of CuZn30 brass was investigated in the temperature range between 650 ◦ C and 850 ◦ C. Torsion tests were performed for experimental plan according to test array 5 × 4, i.e. five temperatures 650, 700, 750, 800, 850 ◦ C and four speeds of torsion shear strain rate 0.5, 2.5, 12.5, and 25 s −1 . Mathematical model has been developed to predict high-temperature shear stress behaviour of CuZn30 brass. Explicit equation, which is a function of peak stress, temperature and shear strain rate, was used in the mathematical model. There are four constants in the equation; one of those is the activation energy which for CuZn30 brass reaches the value Q = 180.3 kJ mol −1 . Measured and calculated values of shear stress are shown in graphs in dependence on the value of deformation, where the temperature of deformation and the speed of deformation are the parameters for the particular curves. The predicted results are in accordance with the experimental curves...
High corrosion resistance of brass against water is the main feature which predestimates its use.... more High corrosion resistance of brass against water is the main feature which predestimates its use. Other features of brass include good machinability after adding 2 to 3 % of lead. Clean binary alfa brass is suitable for cold forming. Significant position in the group of alfa brass has cartridge brass which contains 70 to 72 % of copper and the rest makes zinc. Classical technology of brass cup manufacturing uses rolled semi-product as an entry. Newer non-waste technologies use as an input semi-product bars or wires for the manufacture of cups. The manufacture of bars from brass CuZn30 determined for cup manufacturing and subsequently cartridge manufacturing needs principal technological changes. Hot extrusion of rods, cold rods drawing and interstage annealing belong to decisive METAL 2009 19. – 21. 5. 2009, Hradec nad Moravicí ___________________________________________________________________________ 2 manufacturing operations. Cartridge manufacturing which uses the technology of ...
The present paper gives a summary of the plastic behaviour of the Ms70 deep-drawing cartridge bra... more The present paper gives a summary of the plastic behaviour of the Ms70 deep-drawing cartridge brass under the hot-forming conditions explored by using a SETARAM-Vítkovice torsion plastometer. The specimens were cut from the hot-extruded and, subsequently, cold-drawn brass bars. Formability tests were performed on the diameter 6 mm specimens at (650, 700, 750, 800 and 850) °C and at the speeds of (16, 80, 400 and 800) r/min. These testing conditions are equivalent to the conditions of the ordinary industrial hot extrusion of brass: the single most problematic operation in the manufacturing process in terms of an occurrence of serious defects. The results of the torsion tests were converted into the conventional format: the maximum flow-stress levels vs. the peak-strain intensity. The points thus obtained can be used for finding the activation energy for forming Q, which is useful for determining the thermally compensated strain rate with the aid of the Zener-Hollomon Z parameter. The...
The paper analyzes force distribution necessary to keep the plug in deformation zone. Relation wh... more The paper analyzes force distribution necessary to keep the plug in deformation zone. Relation which determines functional dependence of the cone part diameter of plug on the length of cylindrical sizing part of plug is derived from the equation of force equilibrium in axial direction of the plug. Two drawing die parameters are defined: gap v and overlap p. The parameters determine coefficient of overlap kp which significantly characterizes the process of tubes drawing with support of a floating plug. Nevertheless, the development of tube drawing process with support provided by a floating plug moved our limit up to the production of thick tubes. The paper states conditions under which thick tubes drawing is possible and states how to determine some proportions of drawing dies in order to ensure stable drawing. Confirmed possibility of thick tubes drawing with support provided by a floating plug having negative overlap is the result of theoretical study and practical verification, w...
There is one subsistent group of relations based on theoretical knowledge which are used for the ... more There is one subsistent group of relations based on theoretical knowledge which are used for the average contact pressure calculation on smooth roll s. The second group of relations is generated by empirical equations valid in restricted area of application. The new hypothesis of contact pressure distribution in dependence on rolling cond itions is presented in this submission. A new term of non-dimensional value has been defined as r elative stress. An equation for the average contact pressure calculation, presented by author m oves the mathematical theory of rolling closer to practice. The relative stress is dependan t on ratio ld/h av , reduction intensity and friction coefficient. The equation of relative stress in ave rage contact pressure calculation allows for the presence of a minimum. The verification of new hypothesis of contact pressure distribution is in good consent with data measured in rolling practice .
The examination of the high temperature plastic properties of metallic materials was realised by ... more The examination of the high temperature plastic properties of metallic materials was realised by the torsion plastometer SETARAM or by the compression plastometer DIL805A/D. The brass CuZn30 was used as the test material. Peak stress detection was performed for two independent variables, temperature and velocity of deformation. The set experimental plan forms the test array 5´4, i.e. five temperatures 650, 700, 750, 800, 850 °Cand four strain rates of 0.5, 2.5, 12.5 and 25 s-1. It was necessary to evaluate measured data and to determine the mathematical model of the peak stress. For this aim, the Garofalo equation was used. This equation contains 4 material constants. The currently method used to determine the material constants takes a relatively long time and requires a number of auxiliary calculations. In this method, nonlinear regression is often used, which requires the initial estimation of parameters. The article presents a mathematical analysis and a simple methodology for c...
High corrosion resistance of brass against water is the main feature which predestimates its use.... more High corrosion resistance of brass against water is the main feature which predestimates its use. Other features of brass include good machinability after adding 2 to 3 % of lead. Clean binary alfa brass is suitable for cold forming. Significant position in the group of alfa brass has cartridge brass which contains 70 to 72 % of copper and the rest makes zinc. Classical technology of brass cup manufacturing uses rolled semi-product as an entry. Newer non-waste technologies use as an input semi-product bars or wires for the manufacture of cups. The manufacture of bars from brass CuZn30 determined for cup manufacturing and subsequently cartridge manufacturing needs principal technological changes. Hot extrusion of rods, cold rods drawing and interstage annealing belong to decisive
The calculation of average material contact pressure to rolls base on mathematical theory of roll... more The calculation of average material contact pressure to rolls base on mathematical theory of rolling process given by Karman equation was solved by many authors. The solutions reported by authors are used simplifications for solution of Karman equation. The simplifications are based on two cases for approximation of the circular arch: (a) by polygonal curve and (b) by parabola. The contribution of the present paper for solution of two-dimensional differential equation of rolling is based on description of the circular arch by equation of a circle. The new term relative stress as nondimensional variable was defined. The result from derived mathematical models can be calculated following variables: normal contact stress distribution, front and back tensions, angle of neutral point, coefficient of the arm of rolling force, rolling force, and rolling torque during rolling process. Laboratory cold rolled experiment of CuZn30 brass material was performed. Work hardening during brass proce...
The determination of ductile fracture criteria as well as friction coefficient, stress-strain cur... more The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.
The determination of ductile fracture criteria as well as friction coefficient, stress-strain cur... more The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.
The determination of ductile fracture criteria as well as friction coefficient, stress-strain cur... more The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.
Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are us... more Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are usually required if surface turbulence is to be eliminated. Latest research has demonstrated, that for every liquid metal there is critical velocity above which the surface will fold over and entrain itself in the bulk of the metal. Therefore the strength properties the aluminium castings are largely determined by microstructural defects, particularly pores and oxide films which are created by surface turbulence. The purpose of this paper is to investigate tensile properties and microstructure of aluminium alloy in a casted state two different designs of gating system. The first is the usual bottom gating system and the second is novel design of gating system named a vortex-gate introduced by Campbell [1]. The results of the mechanical tests revealed that there is a small improvement in ultimate tensile strength for vortex-gate design of pouring system. The oxide film defects were observed in microstructure of a sample taken from poured casting by using the bottom gated system.
Cartridge brass is represented by deep-drawing bra ss marked as Ms70 (CuZn30 according to DIN sta... more Cartridge brass is represented by deep-drawing bra ss marked as Ms70 (CuZn30 according to DIN standards). Classical brass cartri dge manufacturing technology uses rolled brass sheets as input semiproduct. Continuous press ure on manufacturing costs caused technological change which has introduced the manufacture of brass cartridges from bars. Brass bars are manufactured by hot extrusion pressing and subsequent cold drawing. The hot extrusion
Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are us... more Aluminium-silicon castings are typically produced by gravity casting. Bottom gated systems are usually required if surface turbulence is to be eliminated. Latest research has demonstrated, that for every liquid metal there is critical velocity above which the surface will fold over and entrain itself in the bulk of the metal. Therefore the strength properties the aluminium castings are largely determined by microstructural defects, particularly pores and oxide films which are created by surface turbulence. The purpose of this paper is to investigate tensile properties and microstructure of aluminium alloy in a casted state two different designs of gating system. The first is the usual bottom gating system and the second is novel design of gating system named a vortex-gate introduced by Campbell [1]. The results of the mechanical tests revealed that there is a small improvement in ultimate tensile strength for vortex-gate design of pouring system. The oxide film defects were observed...
Abstrakt V príspevku autori opisujú viaceré technické riešenia zvyšovania ivotnosti kovacích záp... more Abstrakt V príspevku autori opisujú viaceré technické riešenia zvyšovania ivotnosti kovacích zápustiek, ktoré sú realizované vo výrobnej praxi. Poukazujú na rozdielnosti v prístupoch pri aplikácii tej ktorej metódy ovplyvovania ivotnosti kovacích nástrojov. V príspevku sú uvedené konkrétne výsledky zo sledovania ivotnosti vytypovaných ková �skych zápustiek pracujúcich za tepla. Sledovanie ivotnosti sa uskutonilo priamo vo výrobných podmienkach. V príspevku sú zhrnuté výsledky z piatich technologických riešení zvyšovania ivotnosti ková �skych zápustiek, priom kadé z riešení má svoje špecifiká. Pred zápustkovým kovaním je dôleité komplexné posúdenie faktorov, ktoré do technologického procesu vstupujú, teda stroj, výkovok, nástroj. Z opísaných technologických riešení je moné potom navrhnú � práve také, ktorým je moné zásadne pozitívne ovplyvni� ivotnosdrahého kovacieho nástroja, ktorým kovacia zápustka je. ivotnoszápustky zásadne ovplyvuje správny výber materiálu. Z tohto po...
X-Ray and Neutron Structure Analysis in Materials Science, 1989
An analysis can be regarded as a process of changing the degree of uncertainty with respect to th... more An analysis can be regarded as a process of changing the degree of uncertainty with respect to the unknown values. The goal of an analysis is then to gain a maximum decrease of uncertainty. This implies that the decrease of uncertainty also describes the inadequacy of the analysis and may be considered as a measure for the amount of information obtained1,2,3. X-ray diffraction is a very powerful analytical technique since it enables to obtain a lot of information on the structure of matter: its phase composition, molecular structure, and real structure. The information content of X-ray diffraction analytical techniques can further be extended when they are applied to the examination of processes.
High temperature plastic deformation of CuZn30 brass was investigated in the temperature range be... more High temperature plastic deformation of CuZn30 brass was investigated in the temperature range between 650 ◦ C and 850 ◦ C. Torsion tests were performed for experimental plan according to test array 5 × 4, i.e. five temperatures 650, 700, 750, 800, 850 ◦ C and four speeds of torsion shear strain rate 0.5, 2.5, 12.5, and 25 s −1 . Mathematical model has been developed to predict high-temperature shear stress behaviour of CuZn30 brass. Explicit equation, which is a function of peak stress, temperature and shear strain rate, was used in the mathematical model. There are four constants in the equation; one of those is the activation energy which for CuZn30 brass reaches the value Q = 180.3 kJ mol −1 . Measured and calculated values of shear stress are shown in graphs in dependence on the value of deformation, where the temperature of deformation and the speed of deformation are the parameters for the particular curves. The predicted results are in accordance with the experimental curves...
High corrosion resistance of brass against water is the main feature which predestimates its use.... more High corrosion resistance of brass against water is the main feature which predestimates its use. Other features of brass include good machinability after adding 2 to 3 % of lead. Clean binary alfa brass is suitable for cold forming. Significant position in the group of alfa brass has cartridge brass which contains 70 to 72 % of copper and the rest makes zinc. Classical technology of brass cup manufacturing uses rolled semi-product as an entry. Newer non-waste technologies use as an input semi-product bars or wires for the manufacture of cups. The manufacture of bars from brass CuZn30 determined for cup manufacturing and subsequently cartridge manufacturing needs principal technological changes. Hot extrusion of rods, cold rods drawing and interstage annealing belong to decisive METAL 2009 19. – 21. 5. 2009, Hradec nad Moravicí ___________________________________________________________________________ 2 manufacturing operations. Cartridge manufacturing which uses the technology of ...
The present paper gives a summary of the plastic behaviour of the Ms70 deep-drawing cartridge bra... more The present paper gives a summary of the plastic behaviour of the Ms70 deep-drawing cartridge brass under the hot-forming conditions explored by using a SETARAM-Vítkovice torsion plastometer. The specimens were cut from the hot-extruded and, subsequently, cold-drawn brass bars. Formability tests were performed on the diameter 6 mm specimens at (650, 700, 750, 800 and 850) °C and at the speeds of (16, 80, 400 and 800) r/min. These testing conditions are equivalent to the conditions of the ordinary industrial hot extrusion of brass: the single most problematic operation in the manufacturing process in terms of an occurrence of serious defects. The results of the torsion tests were converted into the conventional format: the maximum flow-stress levels vs. the peak-strain intensity. The points thus obtained can be used for finding the activation energy for forming Q, which is useful for determining the thermally compensated strain rate with the aid of the Zener-Hollomon Z parameter. The...
The paper analyzes force distribution necessary to keep the plug in deformation zone. Relation wh... more The paper analyzes force distribution necessary to keep the plug in deformation zone. Relation which determines functional dependence of the cone part diameter of plug on the length of cylindrical sizing part of plug is derived from the equation of force equilibrium in axial direction of the plug. Two drawing die parameters are defined: gap v and overlap p. The parameters determine coefficient of overlap kp which significantly characterizes the process of tubes drawing with support of a floating plug. Nevertheless, the development of tube drawing process with support provided by a floating plug moved our limit up to the production of thick tubes. The paper states conditions under which thick tubes drawing is possible and states how to determine some proportions of drawing dies in order to ensure stable drawing. Confirmed possibility of thick tubes drawing with support provided by a floating plug having negative overlap is the result of theoretical study and practical verification, w...
There is one subsistent group of relations based on theoretical knowledge which are used for the ... more There is one subsistent group of relations based on theoretical knowledge which are used for the average contact pressure calculation on smooth roll s. The second group of relations is generated by empirical equations valid in restricted area of application. The new hypothesis of contact pressure distribution in dependence on rolling cond itions is presented in this submission. A new term of non-dimensional value has been defined as r elative stress. An equation for the average contact pressure calculation, presented by author m oves the mathematical theory of rolling closer to practice. The relative stress is dependan t on ratio ld/h av , reduction intensity and friction coefficient. The equation of relative stress in ave rage contact pressure calculation allows for the presence of a minimum. The verification of new hypothesis of contact pressure distribution is in good consent with data measured in rolling practice .
The examination of the high temperature plastic properties of metallic materials was realised by ... more The examination of the high temperature plastic properties of metallic materials was realised by the torsion plastometer SETARAM or by the compression plastometer DIL805A/D. The brass CuZn30 was used as the test material. Peak stress detection was performed for two independent variables, temperature and velocity of deformation. The set experimental plan forms the test array 5´4, i.e. five temperatures 650, 700, 750, 800, 850 °Cand four strain rates of 0.5, 2.5, 12.5 and 25 s-1. It was necessary to evaluate measured data and to determine the mathematical model of the peak stress. For this aim, the Garofalo equation was used. This equation contains 4 material constants. The currently method used to determine the material constants takes a relatively long time and requires a number of auxiliary calculations. In this method, nonlinear regression is often used, which requires the initial estimation of parameters. The article presents a mathematical analysis and a simple methodology for c...
High corrosion resistance of brass against water is the main feature which predestimates its use.... more High corrosion resistance of brass against water is the main feature which predestimates its use. Other features of brass include good machinability after adding 2 to 3 % of lead. Clean binary alfa brass is suitable for cold forming. Significant position in the group of alfa brass has cartridge brass which contains 70 to 72 % of copper and the rest makes zinc. Classical technology of brass cup manufacturing uses rolled semi-product as an entry. Newer non-waste technologies use as an input semi-product bars or wires for the manufacture of cups. The manufacture of bars from brass CuZn30 determined for cup manufacturing and subsequently cartridge manufacturing needs principal technological changes. Hot extrusion of rods, cold rods drawing and interstage annealing belong to decisive
The calculation of average material contact pressure to rolls base on mathematical theory of roll... more The calculation of average material contact pressure to rolls base on mathematical theory of rolling process given by Karman equation was solved by many authors. The solutions reported by authors are used simplifications for solution of Karman equation. The simplifications are based on two cases for approximation of the circular arch: (a) by polygonal curve and (b) by parabola. The contribution of the present paper for solution of two-dimensional differential equation of rolling is based on description of the circular arch by equation of a circle. The new term relative stress as nondimensional variable was defined. The result from derived mathematical models can be calculated following variables: normal contact stress distribution, front and back tensions, angle of neutral point, coefficient of the arm of rolling force, rolling force, and rolling torque during rolling process. Laboratory cold rolled experiment of CuZn30 brass material was performed. Work hardening during brass proce...
The determination of ductile fracture criteria as well as friction coefficient, stress-strain cur... more The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.
The determination of ductile fracture criteria as well as friction coefficient, stress-strain cur... more The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.
The determination of ductile fracture criteria as well as friction coefficient, stress-strain cur... more The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.
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