Mladen Franz - Profile on Academia.edu (original) (raw)
Papers by Mladen Franz
Traceability in Force Measurement in Republic of Croatia
In this study based on previous calibrations and factory specifications, an analysis of equipment... more In this study based on previous calibrations and factory specifications, an analysis of equipment for measurement of force in Republic of Croatia has been made. Transfer force standards of the Laboratory for Testing Mechanical Properties ( LIMS) have been calibrated at HBM, Germany. Obtained curves of calibration for single transfer standards were used to estimate standard uncertainties and also the expanded uncertainty of measurement was calculated at every measuring point, according to document EA- 4/15. The best measuring capability of the Laboratory was estimated and the scheme for equipment calibration for the measurement of force in Croatia was developed. Comparing of previous and the last results of the calibration for same transfer standards, conclusion about the influence of the use to the characteristics of standards during a period of time made was made.
The influence of temperature on mechanical properties and pseudoelastic behavior CuZn26Al4 alloy
Hardness Of Heat Treated Cu-Shape Memory Alloy
Bakrena slitina s efektom prisjetljivosti oblika toplinski je obrađena u podrucju temperatura 600... more Bakrena slitina s efektom prisjetljivosti oblika toplinski je obrađena u podrucju temperatura 600°C do 800°C. Tvrdoca slitine izmjerena je metodom po Vickersu s nekoliko razlicitih opterecenja utiskivanja indentora: 0, 098 N (HV 0, 01), 4, 9 N (HV 0, 5), 9, 8 N (HV 1) i 98, 1 N (HV 10). Kada se tvrdoca ispituje metodom HV 0, 01 slijedi stvarna tvrdoca strukturnih faza, a mjerenja s vecim opterecenjima rezultiraju pojavom pseudo-tvrdoca uslijed mehanicki inducirane martenzitne transformacije. Promjene kemijskog sastava koje nastupaju porastom temeperature betatizacije unutar dvofaznog podrucja 600°C do 670°C vode blagom snižavanju stvarne tvrdoce beta-faze i znacajnom porastu tvrdoce alfa-faze. Vrijednosti izmjerenih pseudo-tvrdoca determiniranih silom utiskivanja indentora ne ovise o provedenoj toplinskoj obradi.
Analysis Of Performance Change Of Traveling Force Standard z4-20 kN During Exploitation
Pri umjeravanju mjerila sile prijenosni etaloni sile podvrgnuti su određenim uvjetima koji tijeko... more Pri umjeravanju mjerila sile prijenosni etaloni sile podvrgnuti su određenim uvjetima koji tijekom vremena dovode do promjena njihovih karakteristika. Postavlja se pitanje da li je moguce, na temelju pracenja promjena karakterstika prijenosnog etalona sile tijekom uporabe, predvidjeti vrijednost promjene pojedine karakteristike u slijedecem umjernom razdoblju etalona sile i kao takvu je uvrsitit u proracun mjerne nesigurnosti umjeravanja mjerila sile. U radu je provedeno pracenje karakteristika prijenosnog etalona sile Z4-20 kN tijekom tri umjerna perioda, gdje je u svakom intervalu s ovim etalonom provedeno umjeravanje oko pedestipet mjerila sile. Analiza je provedena na rezultatima umjeravanja ovog prijenosnog etalona sile 1998, 2000, 2002. i 2005. godine u PTB-u, Njemacka. Na temelju provedene analize dani su određeni zakljucci.
Reliability assessment of Francis turbines damaged by cracks
The thesis presents theoretical and experimental analysis of the problems related to the occurren... more The thesis presents theoretical and experimental analysis of the problems related to the occurrence and propagation of cracks on the Francis water turbine rotor runners. Special attention has been paid to the causes which affect the cracks initialization and fast propagation in connection with material properties and the action of external and internal forces, as well as water as the working medium. The thesis combines the results of non destructive (NDT) method test and the results of material experimental testing, accompanied by applicable theoretical methods. In the experimental part of the thesis, complex testing of microstructure and mechanical properties of material on samples taken from practice were performed, determining also the fracture toughness (K1c). From the application of experimental results, selected characteristic cracks and known stresses, the calculated critical and allowed length of the cracks were calculated by using LEFA and NLFA fracture mechanics. Based on all the performed analyses of turbine component materials and calculation results by using fracture mechanics methods, the causes of cracks initialization and their propagation in working conditions have been determined and actions have been recommended for systematic monitoring of the cracks and turbine rotor runner.
Thermal Transformation Behavior of the Two-Phase Shape Memory CuZnAl Alloy
Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range... more Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range of thermally induced martensitic and austenitic transformation. The studied alloy features transformation behavior of a shape memory characteristic. Full reversible transformability of austenitic structure was recorded in all samples treated in the temperature range from 600°C to 670°C. The martensitic transformation occurs by cooling to a sufficiently low temperature, lower or equal to Mf, and austenitic transformation which renews the parent beta-phase in its original form occurs by heating to the temperature equal or higher than Af. Reversible thermally induced transformation is characterized by specific micro-structural transformation flow. The position of the temperature range of the transformational cycle is determined by the betatizational heating within the two-phase alpha/beta-range. Lower temperatures of betatization render the movement of the austenite/martensite-interface more difficult. The lowering of transformation temperatures is related to numerous borders of anti-phase ranges and the change of the zinc content in the austenitic matrix.
The influence of Nb content on the mechanical properties of micro alloyed low carbon steels
Journal of Material Sciences & Engineering, Jun 27, 2018
Mehanička svojstva materijala
Procjena Mjerne Nesigurnosti Pri Umjeravanju Prijenosnih Etalona Sile
Zbornik simpozija, 2001
Svojstva i karakteristike materijala - Katalog opisa
Properties and characteristics of materials - Cataloque of descriptions
Opisi fizikalnih, mehanickih, tehnoloskih, otpornosti medijima, triboloskih i ostalih svojstava i... more Opisi fizikalnih, mehanickih, tehnoloskih, otpornosti medijima, triboloskih i ostalih svojstava i karakteristika materijala, kao i standardnih postupaka ispitivanja - definicije, nacini i postupci ispitivanja, nacini izražavanja vrijednosti, znacenje i primjenjivost, norme za ispitivanje, okvirne vrijednosti za pojedine skupine i vrste materijala. Hrvatsko-njemacko-engleski pojmovnik.
The Measurement Capability of the Reference Force Standard Installed in Lims
Laboratorij za ispitivanje mehanickih svojstva (LIMS) Fakulteta strojarstva i brodogradnje je nos... more Laboratorij za ispitivanje mehanickih svojstva (LIMS) Fakulteta strojarstva i brodogradnje je nositelj državnog etalona za silu u mjernom podrucju 50 N – 200 kN s mjernom sposobnoscu <0, 12%. Krajem 2005. u LIMS-u je instaliran referentni etalon sile nazivne vrijednosti 500 kN. U radu je opisana sljedivost mjerenja sile u RH prije i poslije instalacije referentnog etalona. Procjena mjerne sposobnosti dana je na temelju preliminarnih komparativnih mjerenja provedenih pomocu posrednickih etalona nazivnih sila 20 kN, 50 kN, 100 kN, 200 kN i 500 kN koji su sljedivi do nacionalnih etalona sile Republike Njemacke. Posrednicki etaloni koristeni su u mjernom podrucju 40 -100 % vrijednosti nazivne sile kako bi se dobila sto manja nesigurnost mjerenja. Na temelju izvrsenih mjerenja doneseni su određeni zakljucci koji su ujedno i daljnje smjernice za poboljsanje mjerne sposobnosti referentnog etalona sile. Poseban naglasak je na utjecaju referentnog etalona na mjernu sposobnost LIMS-a, te n...
Properties and application of shape memory alloys
Slitine s efektom prisjetljivosti oblika predstavljaju nove materijale koji posjeduju i posve nov... more Slitine s efektom prisjetljivosti oblika predstavljaju nove materijale koji posjeduju i posve nova svojstva. Njihovo je karakteristicno obilježje sposobnost pamcenja oblika. Da bi materijal pamtio oblik nužna je prisutnost reverzibilne fazne transformacije austenita u martenzit. Doticna se pretvorba može potaknuti mehanickim i/ili toplinskim putem. S obzirom na nacin kako je pretvorba inducirana razlikuju se tri efekta prisjetljivosti oblika: pseudoelasticni, pseudoplasticni (jednosmjerni efekt) te dvosmjerni efekt. Specificne znacajke pojedinih efekata određuju podrucja moguce primjene. U zemljama s visokim stupnjem tehnoloskog razvoja (SAD, Japan, Njemacka) slitine s efektom prisjetljivosti oblika nalaze komercijalnu primjenu na mnogim podrucjima posebice u medicini te tehnici gdje se cesto rabe kao osjetnici (senzori) i pokretaci (aktuatori). U Hrvatskoj su ove slitine nažalost jos uvijek vrlo malo poznate, ali jedan sustavni i sveobuhvatni rad na ovom vrlo interesantnom podrucju...
Study of martensitic-austenitic transformation in Cu-shape memory alloys
Transactions of Famena, 2002
U radu je istraživano osobito ponasanje slitina s efektom prisjetljivosti oblika unutar temperatu... more U radu je istraživano osobito ponasanje slitina s efektom prisjetljivosti oblika unutar temperaturnog podrucja toplinski i mehanicki inducirane martenzitne pretvorbe. Ispitivanja su provedena na CuZn27Al3 i CuZn26Al4 slitinama betatiziranim u podrucju stabilnog, homogenog austenita pri temperaturi 750 °C odnosno 800 °C. Martenzitna i austenitna transformacija analizirane su pomocu diferencijalne pretražne kalorimetrije, metalografskih ispitivanja te ispitivanja mehanickih svojstva unutar podrucja transformacijskog ciklusa. Pri tome je zabilježena potpuna reverzibilna transformabilnost visokotemperaturne austenitne strukture. Osim toga ispitivanja su pokazala da toplinski i mehanicki inducirana martenzitna pretvorba znacajno utjece na mehanicku otpornost slitine.
Reliability assessment of Francis turbines damaged by cracks
The thesis presents theoretical and experimental analysis of the problems related to the occurren... more The thesis presents theoretical and experimental analysis of the problems related to the occurrence and propagation of cracks on the Francis water turbine rotor runners. Special attention has been paid to the causes which affect the cracks initialization and fast propagation in connection with material properties and the action of external and internal forces, as well as water as the working medium. The thesis combines the results of non destructive (NDT) method test and the results of material experimental testing, accompanied by applicable theoretical methods. In the experimental part of the thesis, complex testing of microstructure and mechanical properties of material on samples taken from practice were performed, determining also the fracture toughness (K1c). From the application of experimental results, selected characteristic cracks and known stresses, the calculated critical and allowed length of the cracks were calculated by using LEFA and NLFA fracture mechanics. Based on ...
Redovitim ispitivanjem plinovoda utvrđena je prevelika propusnost te je pritezanje vijaka na slav... more Redovitim ispitivanjem plinovoda utvrđena je prevelika propusnost te je pritezanje vijaka na slavini uzrokovalo puknuce prirubnice na manjem dijelu kucista slavine. Uzroci loma analizirani su na temelju fraktografskog ispitivanja prijelomne povrsine, analize kemijskog sastava, mikrostrukturne analize i ispitivanja mikrotvrdoce. Rezultati ispitivanja su pokazali da slavina nije izrađena od celicnog lijeva vec krhkog sivog lijeva opcenito niže mehanicke otpornosti posebice u uvjetima vlacnog naprezanja. Lom prirubnice u trenutku pritezanja vijaka uzrokovan je superponiranjem uvedenih naprezanja s vec postojecim eksploatacijskim naprezanjima cijem porastu su pogodovali koncentratori naprezanja konstrukcijskog porijekla te mikrostrukturni koncentratori u obliku lamelama grafita kao i vec postojece pukotine kroz koje je istjecao plin, zbog porasta naprezanja u korijenu pukotina i dakako manje nosive povrsine stjenke slavine. Međusobna interakcija navedenih cimbenika dovela je do nestabil...
Traceability in Force Measurement in Republic of Croatia
In this study based on previous calibrations and factory specifications, an analysis of equipment... more In this study based on previous calibrations and factory specifications, an analysis of equipment for measurement of force in Republic of Croatia has been made. Transfer force standards of the Laboratory for Testing Mechanical Properties ( LIMS) have been calibrated at HBM, Germany. Obtained curves of calibration for single transfer standards were used to estimate standard uncertainties and also the expanded uncertainty of measurement was calculated at every measuring point, according to document EA- 4/15. The best measuring capability of the Laboratory was estimated and the scheme for equipment calibration for the measurement of force in Croatia was developed. Comparing of previous and the last results of the calibration for same transfer standards, conclusion about the influence of the use to the characteristics of standards during a period of time made was made.
Thermal Transformation Behavior of the Two-Phase Shape Memory CuZnAl Alloy
Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range... more Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range of thermally induced martensitic and austenitic transformation. The studied alloy features transformation behavior of a shape memory characteristic. Full reversible transformability of austenitic structure was recorded in all samples treated in the temperature range from 600°C to 670°C. The martensitic transformation occurs by cooling to a sufficiently low temperature, lower or equal to Mf, and austenitic transformation which renews the parent beta-phase in its original form occurs by heating to the temperature equal or higher than Af. Reversible thermally induced transformation is characterized by specific micro-structural transformation flow. The position of the temperature range of the transformational cycle is determined by the betatizational heating within the two-phase alpha/beta-range. Lower temperatures of betatization render the movement of the austenite/martensite-interface mo...
Transformation temperatures and mechanical properties of ausforming treated Cu-Zn-Al shape memory alloy
Traceability in Force Measurement in Republic of Croatia
In this study based on previous calibrations and factory specifications, an analysis of equipment... more In this study based on previous calibrations and factory specifications, an analysis of equipment for measurement of force in Republic of Croatia has been made. Transfer force standards of the Laboratory for Testing Mechanical Properties ( LIMS) have been calibrated at HBM, Germany. Obtained curves of calibration for single transfer standards were used to estimate standard uncertainties and also the expanded uncertainty of measurement was calculated at every measuring point, according to document EA- 4/15. The best measuring capability of the Laboratory was estimated and the scheme for equipment calibration for the measurement of force in Croatia was developed. Comparing of previous and the last results of the calibration for same transfer standards, conclusion about the influence of the use to the characteristics of standards during a period of time made was made.
The influence of temperature on mechanical properties and pseudoelastic behavior CuZn26Al4 alloy
Hardness Of Heat Treated Cu-Shape Memory Alloy
Bakrena slitina s efektom prisjetljivosti oblika toplinski je obrađena u podrucju temperatura 600... more Bakrena slitina s efektom prisjetljivosti oblika toplinski je obrađena u podrucju temperatura 600°C do 800°C. Tvrdoca slitine izmjerena je metodom po Vickersu s nekoliko razlicitih opterecenja utiskivanja indentora: 0, 098 N (HV 0, 01), 4, 9 N (HV 0, 5), 9, 8 N (HV 1) i 98, 1 N (HV 10). Kada se tvrdoca ispituje metodom HV 0, 01 slijedi stvarna tvrdoca strukturnih faza, a mjerenja s vecim opterecenjima rezultiraju pojavom pseudo-tvrdoca uslijed mehanicki inducirane martenzitne transformacije. Promjene kemijskog sastava koje nastupaju porastom temeperature betatizacije unutar dvofaznog podrucja 600°C do 670°C vode blagom snižavanju stvarne tvrdoce beta-faze i znacajnom porastu tvrdoce alfa-faze. Vrijednosti izmjerenih pseudo-tvrdoca determiniranih silom utiskivanja indentora ne ovise o provedenoj toplinskoj obradi.
Analysis Of Performance Change Of Traveling Force Standard z4-20 kN During Exploitation
Pri umjeravanju mjerila sile prijenosni etaloni sile podvrgnuti su određenim uvjetima koji tijeko... more Pri umjeravanju mjerila sile prijenosni etaloni sile podvrgnuti su određenim uvjetima koji tijekom vremena dovode do promjena njihovih karakteristika. Postavlja se pitanje da li je moguce, na temelju pracenja promjena karakterstika prijenosnog etalona sile tijekom uporabe, predvidjeti vrijednost promjene pojedine karakteristike u slijedecem umjernom razdoblju etalona sile i kao takvu je uvrsitit u proracun mjerne nesigurnosti umjeravanja mjerila sile. U radu je provedeno pracenje karakteristika prijenosnog etalona sile Z4-20 kN tijekom tri umjerna perioda, gdje je u svakom intervalu s ovim etalonom provedeno umjeravanje oko pedestipet mjerila sile. Analiza je provedena na rezultatima umjeravanja ovog prijenosnog etalona sile 1998, 2000, 2002. i 2005. godine u PTB-u, Njemacka. Na temelju provedene analize dani su određeni zakljucci.
Reliability assessment of Francis turbines damaged by cracks
The thesis presents theoretical and experimental analysis of the problems related to the occurren... more The thesis presents theoretical and experimental analysis of the problems related to the occurrence and propagation of cracks on the Francis water turbine rotor runners. Special attention has been paid to the causes which affect the cracks initialization and fast propagation in connection with material properties and the action of external and internal forces, as well as water as the working medium. The thesis combines the results of non destructive (NDT) method test and the results of material experimental testing, accompanied by applicable theoretical methods. In the experimental part of the thesis, complex testing of microstructure and mechanical properties of material on samples taken from practice were performed, determining also the fracture toughness (K1c). From the application of experimental results, selected characteristic cracks and known stresses, the calculated critical and allowed length of the cracks were calculated by using LEFA and NLFA fracture mechanics. Based on all the performed analyses of turbine component materials and calculation results by using fracture mechanics methods, the causes of cracks initialization and their propagation in working conditions have been determined and actions have been recommended for systematic monitoring of the cracks and turbine rotor runner.
Thermal Transformation Behavior of the Two-Phase Shape Memory CuZnAl Alloy
Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range... more Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range of thermally induced martensitic and austenitic transformation. The studied alloy features transformation behavior of a shape memory characteristic. Full reversible transformability of austenitic structure was recorded in all samples treated in the temperature range from 600°C to 670°C. The martensitic transformation occurs by cooling to a sufficiently low temperature, lower or equal to Mf, and austenitic transformation which renews the parent beta-phase in its original form occurs by heating to the temperature equal or higher than Af. Reversible thermally induced transformation is characterized by specific micro-structural transformation flow. The position of the temperature range of the transformational cycle is determined by the betatizational heating within the two-phase alpha/beta-range. Lower temperatures of betatization render the movement of the austenite/martensite-interface more difficult. The lowering of transformation temperatures is related to numerous borders of anti-phase ranges and the change of the zinc content in the austenitic matrix.
The influence of Nb content on the mechanical properties of micro alloyed low carbon steels
Journal of Material Sciences & Engineering, Jun 27, 2018
Mehanička svojstva materijala
Procjena Mjerne Nesigurnosti Pri Umjeravanju Prijenosnih Etalona Sile
Zbornik simpozija, 2001
Svojstva i karakteristike materijala - Katalog opisa
Properties and characteristics of materials - Cataloque of descriptions
Opisi fizikalnih, mehanickih, tehnoloskih, otpornosti medijima, triboloskih i ostalih svojstava i... more Opisi fizikalnih, mehanickih, tehnoloskih, otpornosti medijima, triboloskih i ostalih svojstava i karakteristika materijala, kao i standardnih postupaka ispitivanja - definicije, nacini i postupci ispitivanja, nacini izražavanja vrijednosti, znacenje i primjenjivost, norme za ispitivanje, okvirne vrijednosti za pojedine skupine i vrste materijala. Hrvatsko-njemacko-engleski pojmovnik.
The Measurement Capability of the Reference Force Standard Installed in Lims
Laboratorij za ispitivanje mehanickih svojstva (LIMS) Fakulteta strojarstva i brodogradnje je nos... more Laboratorij za ispitivanje mehanickih svojstva (LIMS) Fakulteta strojarstva i brodogradnje je nositelj državnog etalona za silu u mjernom podrucju 50 N – 200 kN s mjernom sposobnoscu <0, 12%. Krajem 2005. u LIMS-u je instaliran referentni etalon sile nazivne vrijednosti 500 kN. U radu je opisana sljedivost mjerenja sile u RH prije i poslije instalacije referentnog etalona. Procjena mjerne sposobnosti dana je na temelju preliminarnih komparativnih mjerenja provedenih pomocu posrednickih etalona nazivnih sila 20 kN, 50 kN, 100 kN, 200 kN i 500 kN koji su sljedivi do nacionalnih etalona sile Republike Njemacke. Posrednicki etaloni koristeni su u mjernom podrucju 40 -100 % vrijednosti nazivne sile kako bi se dobila sto manja nesigurnost mjerenja. Na temelju izvrsenih mjerenja doneseni su određeni zakljucci koji su ujedno i daljnje smjernice za poboljsanje mjerne sposobnosti referentnog etalona sile. Poseban naglasak je na utjecaju referentnog etalona na mjernu sposobnost LIMS-a, te n...
Properties and application of shape memory alloys
Slitine s efektom prisjetljivosti oblika predstavljaju nove materijale koji posjeduju i posve nov... more Slitine s efektom prisjetljivosti oblika predstavljaju nove materijale koji posjeduju i posve nova svojstva. Njihovo je karakteristicno obilježje sposobnost pamcenja oblika. Da bi materijal pamtio oblik nužna je prisutnost reverzibilne fazne transformacije austenita u martenzit. Doticna se pretvorba može potaknuti mehanickim i/ili toplinskim putem. S obzirom na nacin kako je pretvorba inducirana razlikuju se tri efekta prisjetljivosti oblika: pseudoelasticni, pseudoplasticni (jednosmjerni efekt) te dvosmjerni efekt. Specificne znacajke pojedinih efekata određuju podrucja moguce primjene. U zemljama s visokim stupnjem tehnoloskog razvoja (SAD, Japan, Njemacka) slitine s efektom prisjetljivosti oblika nalaze komercijalnu primjenu na mnogim podrucjima posebice u medicini te tehnici gdje se cesto rabe kao osjetnici (senzori) i pokretaci (aktuatori). U Hrvatskoj su ove slitine nažalost jos uvijek vrlo malo poznate, ali jedan sustavni i sveobuhvatni rad na ovom vrlo interesantnom podrucju...
Study of martensitic-austenitic transformation in Cu-shape memory alloys
Transactions of Famena, 2002
U radu je istraživano osobito ponasanje slitina s efektom prisjetljivosti oblika unutar temperatu... more U radu je istraživano osobito ponasanje slitina s efektom prisjetljivosti oblika unutar temperaturnog podrucja toplinski i mehanicki inducirane martenzitne pretvorbe. Ispitivanja su provedena na CuZn27Al3 i CuZn26Al4 slitinama betatiziranim u podrucju stabilnog, homogenog austenita pri temperaturi 750 °C odnosno 800 °C. Martenzitna i austenitna transformacija analizirane su pomocu diferencijalne pretražne kalorimetrije, metalografskih ispitivanja te ispitivanja mehanickih svojstva unutar podrucja transformacijskog ciklusa. Pri tome je zabilježena potpuna reverzibilna transformabilnost visokotemperaturne austenitne strukture. Osim toga ispitivanja su pokazala da toplinski i mehanicki inducirana martenzitna pretvorba znacajno utjece na mehanicku otpornost slitine.
Reliability assessment of Francis turbines damaged by cracks
The thesis presents theoretical and experimental analysis of the problems related to the occurren... more The thesis presents theoretical and experimental analysis of the problems related to the occurrence and propagation of cracks on the Francis water turbine rotor runners. Special attention has been paid to the causes which affect the cracks initialization and fast propagation in connection with material properties and the action of external and internal forces, as well as water as the working medium. The thesis combines the results of non destructive (NDT) method test and the results of material experimental testing, accompanied by applicable theoretical methods. In the experimental part of the thesis, complex testing of microstructure and mechanical properties of material on samples taken from practice were performed, determining also the fracture toughness (K1c). From the application of experimental results, selected characteristic cracks and known stresses, the calculated critical and allowed length of the cracks were calculated by using LEFA and NLFA fracture mechanics. Based on ...
Redovitim ispitivanjem plinovoda utvrđena je prevelika propusnost te je pritezanje vijaka na slav... more Redovitim ispitivanjem plinovoda utvrđena je prevelika propusnost te je pritezanje vijaka na slavini uzrokovalo puknuce prirubnice na manjem dijelu kucista slavine. Uzroci loma analizirani su na temelju fraktografskog ispitivanja prijelomne povrsine, analize kemijskog sastava, mikrostrukturne analize i ispitivanja mikrotvrdoce. Rezultati ispitivanja su pokazali da slavina nije izrađena od celicnog lijeva vec krhkog sivog lijeva opcenito niže mehanicke otpornosti posebice u uvjetima vlacnog naprezanja. Lom prirubnice u trenutku pritezanja vijaka uzrokovan je superponiranjem uvedenih naprezanja s vec postojecim eksploatacijskim naprezanjima cijem porastu su pogodovali koncentratori naprezanja konstrukcijskog porijekla te mikrostrukturni koncentratori u obliku lamelama grafita kao i vec postojece pukotine kroz koje je istjecao plin, zbog porasta naprezanja u korijenu pukotina i dakako manje nosive povrsine stjenke slavine. Međusobna interakcija navedenih cimbenika dovela je do nestabil...
Traceability in Force Measurement in Republic of Croatia
In this study based on previous calibrations and factory specifications, an analysis of equipment... more In this study based on previous calibrations and factory specifications, an analysis of equipment for measurement of force in Republic of Croatia has been made. Transfer force standards of the Laboratory for Testing Mechanical Properties ( LIMS) have been calibrated at HBM, Germany. Obtained curves of calibration for single transfer standards were used to estimate standard uncertainties and also the expanded uncertainty of measurement was calculated at every measuring point, according to document EA- 4/15. The best measuring capability of the Laboratory was estimated and the scheme for equipment calibration for the measurement of force in Croatia was developed. Comparing of previous and the last results of the calibration for same transfer standards, conclusion about the influence of the use to the characteristics of standards during a period of time made was made.
Thermal Transformation Behavior of the Two-Phase Shape Memory CuZnAl Alloy
Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range... more Transformation behavior of the two-phase shape memory CuZnAl alloy has been analyzed in the range of thermally induced martensitic and austenitic transformation. The studied alloy features transformation behavior of a shape memory characteristic. Full reversible transformability of austenitic structure was recorded in all samples treated in the temperature range from 600°C to 670°C. The martensitic transformation occurs by cooling to a sufficiently low temperature, lower or equal to Mf, and austenitic transformation which renews the parent beta-phase in its original form occurs by heating to the temperature equal or higher than Af. Reversible thermally induced transformation is characterized by specific micro-structural transformation flow. The position of the temperature range of the transformational cycle is determined by the betatizational heating within the two-phase alpha/beta-range. Lower temperatures of betatization render the movement of the austenite/martensite-interface mo...
Transformation temperatures and mechanical properties of ausforming treated Cu-Zn-Al shape memory alloy