Pejo Konjatić

• Professor
• Head of Department for Mechanical Design at University of Slavonski Brod

The aim of this study is to provide a solution for the plastic limit pressure and stress intensity factor of the elbows containing a part-through axial semi-elliptical crack by considering various crack sizes. The supporting system and loading conditions of the pipeline are described. The critical part of the observed pipeline was isolated for anal...

Zavareni spojevi su izrazito heterogene strukture, koje se fundamentalno mogu podijeliti na osnovni material (OM), metal zavara (MZ) i zonu utjecaja topline (ZUT). Takva heterogenost mikrostrukture materijala zavarenih spojeva utječe na njihova mehanička svojstva, koja mogu značajno varirati u odnosu na pojedine zone zavara. Lomno ponašanje zavaren...

The journal fluid-film bearing is a vital part of a rotary machine, which has a high load-carrying capacity. Babbitt bearings are commonly used to support the shafts of high-speed machines. Severe damage to the babbitt layer can lead to damage of the shaft journal. Fluid-film bearings installed in high-speed machines are exposed to damage due to th...

The transmission of power and motion in road vehicles with internal combustion engines is achieved by different design variants of differential transmissions. The open differential transmission (ODT) is installed to a greater extent in passenger cars with rear-wheel drive due to its simpler design. Due to its robustness, it is possible to reduce it...

Fused deposition modelling (FDM) 3D printers have the highest annual growth of 21.15% in the field of 3D printing. FDM desktop 3D printers account for 23.69% of FDM printers. The major drawback of FDM desktop printers is product accuracy, which is particularly pronounced when dimensionally inaccurate and multi-part printed products need to be fit t...

U radu su primijenjeni i pokazani različiti načini modeliranja oslonca ostvarenog pomoću vijčanog spoja u komercijalnom programu za analizu metodom konačnih elemenata Solidworks. Kao primjer je razmatran sklop oslonca i jednog konstrukcijskog elementa (nosača), spojenih prednapregnutim vijčanim spojem, opterećenih kombinacijom aksijalnog opterećenj...

This article focused on the experimental and statistical analysis of the mechanical properties of dog-bone samples manufactured by fused deposition modelling (FDM). Two identical materials were examined, i.e., Onyx with carbon fiber but from different series and differently stored. One was kept in the manufacturer package and the other one was kept...

In this paper, the dynamic behavior of a rotor kit with two identical disks located between the plain bearings was analyzed. Modal and harmonic analysis of this rotor kit configuration were performed in the Ansys software package. To calibrate the bearing parameters (stiffness and damping) in the numerical model, experimental measurements of the ro...

The subject of this paper is the calculation of welding costs of the lower pedestal central ring of the hydraulic excavator. Purpose, applications and the main parts and functions of the hydraulic excavator are described in this paper. The effects of major welding methods on the overall standards of time and the main welding costs of the central ri...

This research reveals the influence of different purging conditions on the fusion zone dimensions and shape for stationary autogenous TIG welding of 316L stainless steel. Welding experiments were performed for unpurged and purged weld root side for 7, 14 and 21 seconds of arcing time. Purging was executed with ten seconds of pre-flow and 23 seconds...

Boronizing is a thermochemical treatment performed to produce hard and wear-resistant surface layers. In order to control the process and obtain boride layers with the desired properties, it is very important to know how the boronizing parameters and the chemical composition of the treated steel affect the boronizing. The aim of the present study i...

The objective of this work was to investigate the fracture behavior of a heterogeneous I-shaped welded joint in the context of yield load solutions. The weld was divided into two equal parts, using the metal with the higher yield strength and the metal with the lower yield strength compared to base metal. For both configurations of the I-shaped wel...

The C* integral for the compact tension (CT) specimen is calculated using the estimation equation in ASTM E1457-15. This equation was developed based on the assumption of material homogeneity and is not applicable to a welded CT specimen. In this paper, a modified equation for estimating the C* integral for a welded compact tension (CT) specimen un...

The finite element method is a very useful and practical method of predicting the highest concentrations of stresses and deflection of loaded structures including structures that are produced by the welding process where significant concentrations of stress occur. This paper analyzes the approaches to numerical modelling of the welded joint of the...

Analiza naprezanja u elementima cilindričnog zgloba je urađena uz primjenu različitih rubnih uvjeta u dva različita komercijalna softvera s primjenom metode konačnih elemenata. Razmatrana su tri numerička modela: cijeli sklop uz numerički modeliran kontakt između elemenata, sklop gdje je svornjak zamijenjen numerički definiranom vezom i samo jedan...

Structural integrity assessment of an element (lifting plate) of a mine host rope attachment with a surface crack is performed using the SINTAP/FITNET method. Different geometries of a semi-elliptical crack and load intensities are investigated. Material properties data used in the procedure are experimentally determined via tensile and fracture te...

Many manufacturing processes can induce residual stresses in produced components for high-temperature application. Residual stresses, combined with the primary mechanical stresses, play an important role in structural integrity assessments of high-temperature components. In this paper the elastic and elastic-plastic creep behaviour of mechanically...

Sažetak Pokusi delaminacije s grednim uzorcima se često koriste kod ispitivanja različitih suvremenih materijala sa slojevitom strukturom, i kod različitih vrsta ovih pokusa javljaju se i različiti načini loma (otvaranja pukotine). Kod pokusa s mješovitim načinom loma značajno je s aspekta dizajna napraviti podjelu energije loma na udjele od različ...

The paper deals with the computing method of step shaft deflection in an intended place by using the diameter reduction method. This method is analytically studied on the selected shaft shape at different variants of diameters and individual span lengths, where values of deflection are compared with computed values without using this reduction. The...

The effect of initial plasticity on transient creep in plain strain compact tension C(T) specimen under load control is numerically analyzed in this paper. The detailed finite element (FE) analysis was performed by varying the magnitude of the initial step-load, and for general material properties where different plastic and creep stress exponents...

Mixed-mode fracture in delamination test utilizing double cantilever specimens loaded with bending moments is investigated in the paper. FEM simulations are performed using cohesive zone model where different configurations of test loadings and two critical fracture energy values, ie. two fracture process zone lengths, are considered. Fracture ener...

Original scientific paper This article is focused on experimental research of the friction factor in sliding bearings without relubrication. The research includes study of friction factor values and their comparison depending on load and revolutions measured on sliding pairs, consisting of a sliding bearing and a shaft, without relubrication. The r...

This paper presents research experience related to implementation of vibrations on residual stress relief with the equipment for treatment by vibration method. The paper provides explanation of effects achieved by vibration method when implemented during welding, and elaborates advantages and disadvantages of that method applied after welding proce...

Original scientific paper Delamination (fracture) tests have been numerically investigated using various cohesive zone properties. The test utilises asymmetric and symmetric double cantilever beam specimens loaded with bending moment. Energy release rate contributions from mode I and mode II fracture are calculated using a global and local approach...

The contribution deals with the computing method of step shaft deflection in an intended place by using the diameter reduction method. This method is analytically studied on the selected shaft shape at different variants of diameters and individual span lengths, where values of deflection are compared with computed values without using of this redu...

Solving optimization problems from the standpoint of structural stresses and strains can be carried out scientifically on the example of telescopic jib. It is mainly due to the fact that despite a broad spectrum of the telescopic jib utilization there are no generally valid, scientifically proven and presented theoretical principles for their desig...

Finite element modelling of steady state creep process has been described. Using an analogy of visco-plastic problem with a described procedure, the finite element method has been used to calculate steady state stresses and strains in 2D problems. An example of application of such a procedure have been presented, using real life problem - cylindric...

In many practical situations, high-temperature structures and components contain more than one crack An interaction of such multiple cracks has significant influence on the service life of structures and components. In this paper, the interaction of two identical parallel edge cracks in a finite plate subjected to the remote tension is numerically...

This paper presents theoretical determination of elasticity constants for steam boiler membrane wall as structurally orthotropic plate. Modulus of elasticity and shear modulus are determined in directions parallel and perpendicular to membrane wall pipes for both bending and membrane load. When determining modulus of elasticity for bending load, En...

This paper deals with the influence of technological flaw, occurred during welding of header-nozzle joint using SAW welding process, on the strength of welded joint. Three models of welded joints geometry are modeled: model without flaw, model with assumption of flaw existence around whole length of welded joint in form of torus with 1 mm diameter...

Since welded constructions are widely used in engineering, a certain flaws in welded joints may occur either in process of welding or in exploitation period. Easiest way to prolong working life of such welded construction is to repair welded joint to eliminate possibility of construction failure. Process of repair welding usually gives heterogeneou...

The article deals with the impact of mass flow rate of abrasive in a water jet when penetrating into a material by using the vibration analysis. The vibrations of material were recorded by sensors placedonthe experimental material. Values that were studied were amplitude and FFT (Fast Fourier Transform) spectrum of signal. The stainless steel AISI3...

Engineering Faculty in Slavonski Brod, Croatia Keywords • cylindrical shell • weld misalignment • stresses • API 579 • finite element method • surface circumferential crack • failure assessment diagram (FAD) Abstract The influence of stresses resulting from weld misalign-ment in cylindrical shell circumferential weld joint on the shell integrity ha...

The article deals with the impact of mass flow rate of abrasive in a water jet when penetrating into a material by using the vibration analysis. The vibrations of material were recorded by sensors placed on the experimental material. Values that were studied were amplitude and FFT (Fast Fourier Transform) spectrum of signal. The stainless steel AIS...

The aim of this paper is to establish yield load solutions when the materials inhomogeneity within the weld is present, which is usually the case in repair welding. The effect of yield strength mismatch of welded joints performed with different geometry on the yield load value has been investigated in the context of single edge notched fracture tou...

The fracture of a turbine shaft in the case of overloading can exhibit brittle or plastic failure, depending on the material properties, the turbine-shaft geometry and the form of loading. Usually, when the toughness increases, the stiffness of the shaft material is reduced, which can lead to the plastic twist of the shaft. If the fatigue crack app...

This study investigates fracture behaviour of specimens made of high ductile stainless steel. Investigated material was X 5 CrNi 18 10 steel and the specimens used in this investigation were prepared as centre crack tension (CCT) specimens. Pre-cracking of specimens was done by controlled cycling loading. For determination of J-integral, as one of...

This study investigates fracture behaviour of specimens made of high ductile stainless steel. Investigated material was X 5 CrNi 18 10 steel and the specimens used in this investigation were prepared as centre crack tension (CCT) specimens. Pre-cracking of specimens was done by controlled cycling loading. For determination of J-integral, as one of...

This paper investigates mechanical properties of polyester laminates reinforced with different layers of glass fibres with additives. Testing plates were made by soaking of reinforcements with resin and applying manual air extraction using hand roller. On the basis of results of testing for obtaining tensile, flexural and interlayer strength, modul...