The paper presents the procedure of implicit stress integration for constitutive models for soil and rock. The theoretical basis of Mohr-Coulomb, Matsuoka-Nakai, Hoek-Brown and Hyperbolic soil constitutive models are presented. Stress integration was performed using the theory of incremental plasticity. The general procedure of implicit stress inte...

By Dragan Rakić, Miroslav Živković

This paper presents the integration of muscle fatigue modeling into the finite element solver PAK, based on an extended version of Hill’s phenomenological model. While traditional muscle models focus primarily on force generation, this study incorporates fatigue dynamics to provide a more realistic representation of muscle performance over ti...

By Boban Stojanović, Miloš Kojić, Srboljub Mijailovich

This paper describes software developed based on numerical implementation of algorithms for coupled acoustic – structure interaction. This class of problems implies coupling of the fluid domain, with sound wave propagation, and the domain of solid, which vibrates under the pressure caused by sound waves from the fluid domain. The physical beh...

By Velibor Isailović, Nenad Filipović, Milica Nikolić, Miloš Kojić

Cardiovascular diseases are among the leading causes of mortality worldwide, necessitating advanced computational modeling to study their underlying mechanisms and explore potential treatments. In this paper, we present a multiphysics computational model that integrates cardiac mechanics, electrophysiology, and mass transport, implemented within th...

By Miljan Milošević, Bogdan Milićević, Vladimir Simić, Nenad Filipović, Miloš Kojić

Solvent removal by diffusion from a polymer solution occurs in various technological processes, such dry spinning of synthetic silk-like fibers. There, it is important to determine the diffusion coefficient which is dependent on the solvent concentration, assuming the validity of Fick’s law. In order to prove the internal diffusion within the...

By Aleksandar Kojić, Miloš Kojić, Nikola Kojić

Degradation of structural integrity and fatigue life estimation remain critical challenges in engineering, including biomedical applications. Fracture mechanics and crack propagation prediction are highly sensitive to material parameters, with the Stress Intensity Factor being the most significant physical parameter for the estimation of crack stre...

By Gordana Jovičić, Vladimir Milovanović, Aleksandra Vulović, Miroslav Živković, Nenad Đorđevič, Nenad Filipović

X-ray angiography is one of the diagnostic procedures applied in clinical practice to analyze the state of patient-specific coronary arteries. During this examination a parameter called fractional flow reserve (FFR) is invasively measured to quantitatively assess the existence of potential stenosis and its significance. The software proposed in thi...

By Tijana Đukić, Ognjen Pavić, Lazar Dašić, Tijana Geroski, Nenad Filipović

In this paper, we give a short overview of the basic concept of stress integration for inelastic material models. This methodology was introduced by the author, initially for thermo-elasticplastic and creep deformation of metals, termed as ‘effective-stress-function’ (ESF), and then generalized to the ‘governing parameter method&r...

By Miloš Kojić

The paper presents various examples of the application of the PAK software and its modules for thermal, filtration, and stress–strain analysis of different complex engineering structures such as gravity dams, arch dams, embankment dams, tunnels, and mines. Examples of research, studies, and projects in which PAK has been applied to assess the...

By Dejan Divac, Slobodan Radovanović, Maja Pavić, Nikola Milivojević, Vladimir Milivojević, Miroslav Živković, Dragan Rakić, Snežana Vulović

Two-equation turbulent models are widely used in finite element analysis of fluid flow. The PAK program package was upgraded from the classical laminar flow to the turbulent k-omega model. The turbulence model was validated using the case of fluid flow in a backward-facing step channel. The analysis results show good agreement with experimental dat...

By Aleksandar Nikolić, Miroslav Živković, Nenad Filipović, Marko Topalović