R&D Engineer II · Ansys Part of Synopsys
Ph.D.
Keywords: Computational Mechanics, Fluid-Structure Interaction, Fracture Mechanics, Air-Blast-Structure Interaction, Smoothed Particle Hydrodynamics (SPH), Peridynamics, Phase-field, IGA, FEM
Stony Brook University · 2021 – Present
Thesis: Computational mechanics of extreme events: Advanced multi-physics simulations with Smoothed Particle Hydrodynamics, Isogeometric Analysis, Micro Plane Model, and Phase Field.
Advisor: Georgios Moutsanidis · Location: New York, USA
Sabanci University · 2019 – 2021
Thesis: Peridynamic Modeling of Internal Features and Interfaces for Material Toughening.
Location: Istanbul, Turkey
Inonu University · 2014 – 2018
Honors thesis: Excel-based Programming in Civil Engineering.
Location: Malatya, Turkey
Inonu University · 2015 – 2021
Thesis: Energy Assessment of Bio-wastes in Afghanistan's Kunar City.
Location: Malatya, Turkey
LSDYNA · 2024 – Present
ANSYS-LSDYNA · May 2024 – August 2024
ANSYS-LSDYNA · May 2023 – August 2023
Istanbul Technopark · July 2020 – November 2020
Inonu University, Malatya · June 2017 – August 2017
Guven Constructions · June 2016 – August 2016
Contributor/Research Assistant · PI: Georgios Moutsanidis · NSF CAREER Award #: 2338313
Contributor/Research Assistant · PI: Deniz Can Kolukisa · TÜBİTAK Project ID: 121M425
Author/PI · Project ID: B.A.KM-21-02377
Coding
C++, Fortran, CUDA, MATLAB, and Python.
Open-source Contributions
DualSPHysics-Fracture and particle-based concrete failure solvers (GitHub).
Software
ANSYS-LSDYNA, FEniCS, SolidWorks.
Numerical Methods
SPH, Phase Field, FEM, IGA, and Peridynamics.
Languages
English, Persian, Turkish, and conversational Hindi.
2024 · IACS Junior Researcher Award
Presented by the Institute for Advanced Computational Science (IACS) for outstanding doctoral research.
2024 · SBU Civil Engineering Research Merit Award
Recognizes exceptional research contributions within the Department of Civil Engineering at Stony Brook University.
2023 · Best Student Paper
Awarded by the ASCE Fluid Dynamics Committee at the Engineering Mechanics Institute conference.
2019 · Summa Cum Laude Award
Ranked first out of 940 engineering students at Inonu University.
2018 · First Place in National Undergraduate Thesis Competition
Presented by TÜBİTAK for outstanding undergraduate thesis work.
2017 · Young Merit Award
Recognized by the MISA Organization for exceptional academic and personal achievements.
2011 · Silver Medalist in Mathematics
International Science Olympiad (ISO), Abuja, Nigeria.
2010 · Gold Medalist in Mathematics
National Mathematics Olympiad, Afghanistan.
2019 · Master's Scholarship
Full funding for the Material Science & Nanoengineering M.Sc. program at Sabanci University.
2015 · Double Major Scholarship
Undergraduate Mechanical Engineering scholarship from Inonu University.
2013 · Presidential Scholarship
Government of Afghanistan fully funded Civil Engineering studies in Turkey.
2008 · High School Scholarship
Full scholarship at the International Turkish high school chain in Balkh, Afghanistan.
Steel and Reinforced Concrete Design I (CIV312)
Instructor · Stony Brook University · Jan 2024 – May 2024
Calculus (MATH102)
Teaching Assistant · Sabanci University · Jan 2021 – Jul 2021
Manufacturing Processes (IE309)
Teaching Assistant · Sabanci University · Sep 2020 – Jan 2021
Introduction to Material Science (ENS205)
Teaching Assistant · Sabanci University · Jan 2020 – Jun 2020
Calculus (MATH102)
Teaching Assistant · Sabanci University · Jan 2019 – Jan 2020
Dynamics (DNK201)
Teaching Assistant · Istanbul Technical University · Jan 2019 – Apr 2019
R&D Engineer II · Ansys Part of Synopsys
Ph.D.
Keywords: Computational Mechanics, Fluid-Structure Interaction, Fracture Mechanics, Air-Blast-Structure Interaction, Smoothed Particle Hydrodynamics (SPH), Peridynamics, Phase-field, IGA, FEM
I am an R&D Engineer II at ANSYS (part of Synopsys). I currently work on the development of LS-Dyna software for car crash simulations.
I received my Ph.D. in the field of Computational Mechanics from the Department of Civil Engineering at Stony Brook University, specializing in the development of computational models to predict the failure and inelastic behavior of structures subjected to extreme events. These events include severe hydrodynamic phenomena such as floods and tsunamis, as well as explosions resulting from human error, environmental factors, or terrorism.
My academic background includes bachelor's degrees in civil and mechanical engineering and a master's degree in materials science and nanoengineering. I completed my high school education in Afghanistan and pursued my undergraduate and master's studies in Turkey and Poland.
M. Naqib Rahimi,
Georgios Moutsanidis
Computer Methods in Applied Mechanics and Engineering
View on GitHub
Published on: Feb 2026
Abstract
We introduce SoliDualSPHysics, a novel open-source and GPU-accelerated software that extends DualSPHysics to enable the numerical simulation of hyperelastic, finite-strain plastic, and brittle fracture behavior in deformable solids within a unified smoothed particle hydrodynamics (SPH) formulation. The software implements a total Lagrangian formulation for solid mechanics that allows direct application of external loads and boundary conditions, enabling independent solid mechanics simulations. Brittle fracture is modeled through a phase-field approach coupled with SPH, allowing crack initiation, propagation, and branching under dynamic loading without the need for additional criteria or local refinement. The framework also supports user-defined mathematical expressions to prescribe time- and space-dependent quantities, complementing the solid and fracture extensions and enhancing flexibility across existing and future DualSPHysics applications. Leveraging DualSPHysics' native CPU/GPU parallel architecture, the software achieves substantial computational acceleration for large-scale simulations, and the implementation is verified and validated against benchmark numerical problems and experimental data, demonstrating accuracy, robustness, and favorable scaling performance. Comprehensive implementation details and user documentation are provided to ensure reproducibility and to support further development by the community. The framework and source code are freely available through a public GitHub repository.
M. Naqib Rahimi
Published on: December 2024
Abstract
Extreme hydrodynamic events are escalating in frequency and intensity due to climate change. These phenomena pose catastrophic risks, including severe infrastructure damage, economic losses, and threats to human life. Similarly, air‐blast events propagate destructive pressure waves that endanger structures through rapid loading, fragmentation, and secondary hazards like debris impact. To ensure human safety and mitigate property damage, computational modeling emerges as an essential tool for forecasting the impacts of these events. To successfully implement a computational tool, it is necessary to first address challenges including free-surface flows, fluid-structure contact, and structural deformations; failure, fracture, fragmentation. This dissertation systematically addresses these challenges by developing innovative numerical frameworks for structural damage and fluid-structure interaction (FSI) scenarios. In its first few chapters, this dissertation develops a unified Smoothed Particle Hydrodynamics (SPH)–Phase field framework for simulating brittle fracture and fragmentation in general homogeneous materials and the more complex case of functionally graded materials. To address the numerical complexities arising from combined plastic, damage, and hardening behavior of anisotropic quasi-brittle materials like concrete, the dissertation further introduces an SPH-Microplane M7 open-source C++ platform. The SPH-M7 model decomposes the stress–strain behavior onto microscopic planes to represent anisotropic damage naturally. Building upon these foundational works, this dissertation also presents a fully particle-based non-local approach to address challenges such as structural fracture and fragmentation in modeling extreme hydrodynamic events. The proposed method is supplemented with a novel FSI coupling algorithm, allowing coupled solvers to utilize different particle resolutions for fluid and deformable structural media. The coupling strategy enhances accuracy, stability, and robustness without imposing additional computational cost. In the context of air-blast-structure interaction modeling, this dissertation presents an immersed-like numerical framework that combines Isogeometric analysis with SPH to simulate wave propagations and explosive-induced fracture and fragmentation. The framework uses Lagrangian point clouds for the solid domain and Eulerian fluid domain, featuring a penalty-based volumetric coupling scheme that penalizes the velocity difference. This allows for straightforward implementation, enabling seamless integration of two distinct computational techniques without requiring explicit FSI interface tracking. As the final and most vital objective, a CPU/GPU parallelized open-source platform is developed, improving the existing DualSPHysics open-source package capabilities to be able to solve for structural deformation and brittle fracture of solids. The open-source code will be provided as GitHub repository and is capable of solving two and three dimensional dynamic structural mechanics problem with complex boundary conditions and hyperelastic and/or brittle fracture materials responses. The platform is also supplemented with an enhanced user-defined expression parser that supports inputs as time/space varying expressions containing a wide range of trigonometric, math, and logical operations with nested if clauses. The user-defined expression parser is particularly helpful in problems involving complicated initial states and time/space dependent boundary conditions. This work aligns with broader efforts to expand SPH into multiphysics engineering applications and addresses challenges related to accurate modeling of structural failure in industrial scale extreme hydrodynamic events. Keywords: Smoothed Particle Hydrodynamics, Isogeometric analysis, Micro plane model, Phase field, Fluid-structure interaction, Air–blast-Structure interaction, Extreme events, Brittle fracture, DualSPHysics, Open-source
Mohammad Naqib Rahimi,
Lampros Svolos,
George Moutsanidis
International Journal of Solids and Structures
Published on: Dec 2025
Abstract
Functionally graded materials (FGMs) are advanced composite materials whose spatial gradation in structure and composition leads to tailored characteristics suitable for specific applications and operating conditions. FGMs have been employed in many fields including aerospace, automotive, defense, and biomedical, among others. Modeling crack initiation and propagation in such materials is therefore crucial in order to predict sudden loss of load-carrying capacity and prevent catastrophic failure in extreme environments and under severe loading conditions. A special class of FGMs is functionally graded ultra-high temperature ceramics (FG-UHTCs). These materials feature outer zones of thermally resistant components, such as zirconium diboride (ZrB₂) or hafnium diboride (HfB₂), that grade smoothly into tougher, less brittle inner layers, such as silicon carbide (SiC). FG-UHTCs have primarily been used in hypersonic applications, where the encountered temperatures and pressures are very high. Although the fracture behavior of FGMs and FG-UHTCs under mechanical loading has been studied, research on crack formation and propagation under strong thermal loads remains limited. In this work, motivated by their potential in hypersonic environments, we examine dynamic brittle fracture in FG-UHTCs subjected to extremely high thermal loads typical of hypersonic flight. Leveraging the phase-field method, our primary objective is to develop fundamental insights into whether and how material gradation influences fracture resistance and thermal protection. First, comprehensive mathematical and implementation details for the computational method are provided. Then, the framework is verified and validated against alternative computational approaches and experimental data. Finally, we conduct two representative high-temperature extreme scenarios in which the gradation profile is systematically varied. These examples are specifically designed to quantify how material gradation governs crack initiation, propagation, and overall thermal protection, thereby generating the fundamental insights on the effect of material gradation.
Mohammad Naqib Rahimi,
Georgios Moutsanidis
International Journal of Mechanical Sciences
DOI: 10.1016/j.ijmecsci.2025.110378
View on GitHub
Published on: 01 August 2025
Abstract
Modeling concrete failure under extreme events, such as hypervelocity impact, air-blast loading, or water impact, has long been an open research area in the engineering mechanics community. Over the years, numerous concrete constitutive models capturing failure have been developed and effectively applied within traditional computational techniques, such as the finite element method (FEM). However, research activity involving meshfree and particle-based numerical methods, such as smoothed particle hydrodynamics (SPH), remains limited in this context. This paper presents the first implementation of the evolving microplane (M7) concrete constitutive model within the framework of SPH. The meshfree nature of SPH enables the simulation of scenarios involving extreme deformations, material separation, and discrete fractures, challenges that conventional mesh-based computational techniques often struggle to address. Comprehensive mathematical and implementation details are provided, and the framework is verified and validated through several benchmark tests that demonstrate the applicability of the M7 model in SPH. The framework is further applied to a hypervelocity impact scenario, illustrating its capability to capture fracture and fragmentation under extreme conditions. Finally, to support community adoption, the open-source SPH implementation, including calibration procedures and parameters, is made available via a GitHub repository. This work provides the SPH community with a robust tool for modeling concrete failure and contributes to advancing computational methods for extreme events simulations.
M. Naqib Rahimi,
Georgios Moutsanidis
Journal of Engineering with Computers
DOI: 10.1007/s00366-024-01978-0
Published on: 07 May 2024
Journal Impact Factor: 7.3,
Journal Cite Score: 18.0
Abstract
We introduce a novel immersed-like numerical framework that combines isogeometric analysis with smoothed particle hydrodynamics for simulating air-blast–structure interaction. The solid domain is represented by a Lagrangian point cloud, which is immersed into a background Eulerian fluid domain. The smoothed particle hydrodynamics framework is employed to solve the equations of motion of the solid point cloud, whereas isogeometric analysis is used for the fluid mechanics equations on the background domain. The coupling strategy relies on a penalty-based volumetric coupling scheme that penalizes the velocity difference between the two domains, and involves a minimal amount of modification to existing codes, resulting in a straightforward implementation. The immersed nature of the proposed approach, combined with volumetric coupling, eliminates the need for explicit tracking of fluid–structure interfaces and imposes no limitations on solid domain motion and topology. Ample mathematical details are provided, and the proposed method is verified and validated against established numerical tools and experimental studies. The results affirm the method’s accuracy, robustness, and ease with which it seamlessly integrates two distinct computational techniques.
M. Naqib Rahimi,
Georgios Moutsanidis
Journal of Engineering with Computers
DOI: 10.1007/s00366-023-01857-0
Published on: 14 June 2023
Journal Impact Factor: 7.3,
Journal Cite Score: 18.0
Abstract
We present a proof-of-concept particle-based fluid–structure interaction (FSI) computational framework for modeling structural fracture and fragmentation under the impact of extreme hydrodynamic events. The smoothed particle hydrodynamics (SPH) approach is employed to discretize the equations of motion for both the fluid and structural domains. The meshfree nature of the discretization technique accommodates the simulation of scenarios involving extreme structural deformations and material separation, as well as free-surface flows. The framework is supplemented with a phase-field model of brittle fracture that allows for the simulation of crack nucleation, propagation, and branching, which leads to realistic modeling of structural responses during extreme hydrodynamic events. In the end, a novel algorithm for coupling the fluid and solid subproblems is presented. The proposed approach is verified and validated against existing computational methods and experimental results, and in the end, a few challenging problems involving complex fracture patterns and fragmentation are presented.
M. Naqib Rahimi,
Georgios Moutsanidis
Computer Methods in Applied Mechanics and Engineering
DOI: 10.1016/j.cma.2022.115642
Published on: 01 Nov 2022
Journal Impact Factor: 6.9,
Journal Cite Score: 12.7
Abstract
We present a novel particle-based computational framework for the numerical simulation of dynamic crack propagation in functionally graded materials under highly dynamic loading conditions and large deformations. The approach is based on an innovative computational method that solves phase field of brittle fracture with smoothed particle hydrodynamics. The meshfree nature of the discretization technique allows for the simulation of scenarios involving extreme deformations and material separation, as opposed to conventional mesh-based computational techniques such as the finite element method. At the same time, the damage evolution is governed by a hyperbolic partial differential equation that allows for efficient explicit time integration and avoids the complexities of solving linear systems of equations. The framework is verified and validated against other computational approaches and experimental results. Finally, the proposed approach is applied to some challenging impact scenarios that involve fast dynamics or large deformations, and it is shown that it can be easily used for identifying material gradation profiles that manipulate crack propagation.
M. Naqib Rahimi,
Georgios Moutsanidis
Computer Methods in Applied Mechanics and Engineering
DOI: 10.1016/j.cma.2022.115191
Published on: 01 Aug 2022
Journal Impact Factor: 6.9,
Journal Cite Score: 12.7
Abstract
Fracture is a very challenging and complicated problem with various applications in engineering and physics. Although it has been extensively studied within the context of mesh-based numerical techniques, such as the finite element method (FEM), the research activity within the Smoothed Particle Hydrodynamics (SPH) community remains scarce. SPH is a particle-based numerical method used to discretize equations of continuum media. Its meshfree nature makes it ideal to simulate fracture scenarios that involve extreme deformations. However, to model fracture, SPH researchers have mostly relied on ad-hoc empirical local damage models, cohesive zone approaches, or pseudo-spring models, which come with a set of drawbacks and limitations. On the other hand, phase field models of brittle fracture have recently gained popularity in academic circles and provide significant improvements compared to previous approaches. These improvements include the derivation from fundamental fracture theories, the introduction of non-locality, and the ability to model multiple crack initiation, propagation, branching, and coalescence, in situations where no prior knowledge of the crack paths is available. Nevertheless, phase field for fracture has not been studied within SPH. In this proof-of-concept paper we develop and implement a phase field model of brittle fracture within the context of SPH. Comprehensive mathematical and implementation details are provided, and several challenging numerical examples are computed and illustrate the proposed method’s ability to accurately and efficiently simulate complex fracture scenarios.
M. Naqib Rahimi,
D. Can Kolukisa,
M. Yildiz,
M. Ozbulut,
A. Kefal
Computer Methods in Applied Mechanics and Engineering
DOI: 10.1016/j.cma.2021.114370
Published on: 01 Feb 2022
Journal Impact Factor: 6.9,
Journal Cite Score: 12.7
Abstract
Fluid–structure interaction problems (FSI) are omnipresent in a wide variety of engineering fields and includes highly non-linear physics such as violent free-surface flow, complex interfacial and inter-phase interactions, and deformable structures with the possibility of damage formations. Well-established mesh dependent approaches may suffer from dynamic mesh-refinement, special algorithms to track free surfaces and handle the interface and inter-phase physics. On the other hand, due to their inherent nature, particle based meshless methods, namely Smoothed Particle Hydrodynamics (SPH) and Peridynamics (PD), can lend themselves easily to tackling with the above-stated complex physics involved in the fluid and structure phases of the FSI problems, respectively. This study presents a novel hybrid algorithm to couple the SPH and PD in a robust and high-fidelity manner for modeling extreme FSI problems with and without multi-scale defects. The coupled methodology is integrated with a novel mapping strategy based on Lagrange polynomial interpolation, which allows for the solution procedure to utilize different particle resolutions for fluid and deformable structural media. The mapping strategy enables one to construct a higher-accuracy PD solver that can predict the dynamic behavior of solids and provide an ability to model and track the damage nucleation, propagation, and branching in the structure phase of FSI domains. The corrected weakly compressible SPH is used for pressure–velocity coupling in the fluid phase whereas the ordinary state based PD is utilized for modeling the deformable structure. The SPH and PD solvers of the algorithm are validated separately through solving several well-accepted benchmark test cases such as the collapse of a water column, large deformation of a cantilever beam, and damage propagation in a plate under impact loading (Kalthoff–Winkler experiment). After validating each solver, the hybrid coupled SPH–PD algorithm is applied to simulate various extreme FSI problems of literature such as the dam break with an elastic gate, collapse of the water column and its hydrodynamic impact on an elastic obstacle, and the entry of a V-shaped deformable beam on the free surface of water in a tank. A close agreement between the SPH–PD results and the literature data is achieved for each of the aforementioned cases. The algorithm is further applied to model the failure propagation in the elastic wall of a tank under hydrostatic pressure. A realistic failure behavior is recorded for the FSI setups with different initial states of the wall, i.e., the wall is assumed to be with and without initial defects of different geometrical orientations. In particular, this study proposes and implements a new perspective for coupling different particle methods to achieve high-fidelity and low-cost modeling of complex FSI problems, which may involve multi-scale defects (i.e., cracks and voids) and failure propagations.
M. Naqib Rahimi,
A. Kefal,
M. Yildiz
International Journal of Mechanical Sciences
DOI: 10.1016/j.ijmecsci.2021.106322
Published on: 01 May 2021
Journal Impact Factor: 7.1,
Journal Cite Score: 12.8
Abstract
This study proposes an enhanced formulation of Ordinary-State based peridynamic which can model functionally graded materials (FGMs) with sharp jumps in material properties through introducing a novel peridynamic parameter, referred to as the dominancy rate. The current formulation takes into account the multi-scale nature of peridynamics as well as the material transition (interface) effects. As a result of extensive comparison efforts with FEM literature, traditional peridynamics, and ANSYS, this study reveals that the properties of a PD-bond should not be equally affected by the properties of the constituent points in modeling FGMs. Additionally, it is found that the correctness of the results is negatively influenced if the bond properties are determined using only one of the weaker or stronger constituent point. Moreover, a better accuracy is achieved, specially at the material transition regions, through considering that the properties of the bonds are mostly dependent on that of the weaker constituent point. It is also observed that the current approach can model FGMs with higher accuracy using lower number of material points as compared to the traditional PD. Finally, To Further demonstrate the capability of the proposed model, a numerically validated toughening mechanism against crack propagations is presented for FGMs. It is found that the local toughness of FGMs can be effectively enhanced by tailoring the location and material properties of the sub-regions.
M. Naqib Rahimi,
A. Kefal,
M. Yildiz,
E. Oterkus
International Journal of Mechanical Sciences
DOI: 10.1016/j.ijmecsci.2020.105773
Published on: 15 Sep 2020
Journal Impact Factor: 7.1,
Journal Cite Score: 12.8
Abstract
In this paper, the ordinary state-based peridynamic (OSB) is used to simulate and study the effects of different-shaped stop-holes with different combinations on crack dynamics in brittle materials in order to establish a detailed knowledge about the toughening effect of internal features that can be in the form of holes and pores. Using the OSB analyses, a new easy-to-apply technique is presented to toughen the materials against crack propagations. As a first case study, the high accuracy of peridynamic approach in damage prediction is demonstrated through solving a collection of numerical and experimental benchmark problems. Moreover, the bi-hole, parabolic, branched, bi-parabolic, and mixed-parabolic combinations of stop-holes under tensile loading, and the T-shape, I-shape, bi-linear, linear, and linear-parabolic combinations of stop-holes under shear loading are suggested for notably enhancing material toughness and are practically and functionally compared with each other. Generally, the suggested geometries are proven to be highly effective on toughness enhancement of materials with a relative ease of implementation, in comparison to other internal features such as micro-cracks. In addition, a further case study is carried out on the effects of the distance of stop-holes from the initial crack-tip on crack dynamics and material toughness, in which it is observed that every hole has a specific µ-range, and thus, the crack dynamics are affected by the hole if and only if the crack enters this range. Overall, the arrestment and accelerating effects of the stop-holes on crack dynamics are carefully explained numerically and conceptually, which will help engineers and designers to maximize the positive effects of stop-holes on material toughness and design a tougher micro-structural material using easily applied defects.
B. Alkhateab,
I. E. Tabrizi,
J. S. M. Zanjani,
M. Naqib Rahimi,
L. H. Poudeh,
A. Kefal,
M. Yildiz
Composites Part A: Applied Science and Manufacturing
DOI: 10.1016/j.compositesa.2020.105962
Published on: 01 Sep 2020
Journal Impact Factor: 8.1,
Journal Cite Score: 15.2
Abstract
This study is conducted to thoroughly scrutinize the role of nanotubes on the physics behind the deformation mechanisms and damage development in fiber reinforced polymer composites by using acoustic emission, digital image correlation, infrared thermography, fractography, and non-local meshless-numerical analysis, namely, Peridynamics. Carbon fiber laminates with and without Halloysite nanotubes (HNTs) are prepared and tested under flexural and in-plane shear loads. In depth analysis of the cumulative counts for acoustic emission data shows that the addition of HNTs mainly promotes the failure mechanisms associated with matrix cracking. Digital image correlation and infrared thermography analysis clearly prove that nanotubes prevent the coalescence of microcracks by blocking crack propagation or diverting its path. Fractography analysis shows that HNTs addition improves the interfacial strength despite promoting microcracks in the matrix. The hindrance of crack growth, crack tip splitting, and prevention of crack coalescence by HNTs clusters, are supported successfully by performing Peridynamic analysis.
M. Naqib Rahimi,
O. H. Bettemir
SAVTEK 2018, 9. SAVUNMA TEKNOLOJİLERİ KONGRESİ
File: Access PDF
Published on: 29 Jun 2018
Abstract
In this paper, preliminary design of an unmanned ground vehicle which can execute reconnaissance of caves is performed. The unmanned ground vehicle is preferred to be electric powered in order to provide silence during movement and make it difficult to be detected by thermal cameras. The unmanned system is designed as cable controlled since an autonomous system is not dependable during a clash. On board cameras helps the operator to obtain relevant data about the cave. The vehicle can drill and blast the cave wall and makes the cave unserviceable. The proposed system can reduce the casualties during the war on terrorism.
