Instytut Podstawowych Problemów Techniki

Dera W., Konopacka H., Jarząbek D., Development of a novel nickel-based metal force microsensor using bottom-up approach, Precision Engineering, ISSN: 1873-2372, DOI: 10.1016/j.precisioneng.2025.05.003, pp.251-261, 2025

Abstract:
The advancement of force microsensors has shifted towards alternative fabrication methods offering enhanced flexibility, cost efficiency, and adaptability. Traditional silicon-based sensors face limitations such as mechanical fragility, thermal expansion mismatches, and high fabrication costs, necessitating alternative approaches. This study explores a bottom-up fabrication approach using electro-galvanic deposition to develop nickel-based capacitive force microsensors. Unlike conventional methods, electro-galvanic deposition enables precise control over material thickness and microstructure, allowing for the fabrication of robust, metal-based sensors with superior toughness and mechanical reliability. Nickel, chosen for its high tensile strength, corrosion resistance, and adaptability to high temperatures, is well-suited for demanding applications. The fabrication process involves UV maskless lithography for mold patterning, followed by electro-galvanic deposition in a modified Watt's bath with saccharin additives to control grain structure. This enables fine-tuning of nickel's mechanical properties, enhancing hardness and ductility. The capacitive comb sensor structure, integrated with a high-resolution capacitance-to-digital converter, enables precise force measurements with a linear response and high sensitivity. Experimental validation included mechanical testing, calibration, and stability analysis under controlled loading conditions. Results confirmed a strong linear force-capacitance relationship (R2 = 0.9898) and excellent long-term stability, with minimal capacitance drift under sustained load.

Keywords:
Nickel-based sensor, Bottom-up process for sensor fabrication, Electro-galvanic deposition, Capacitance stability, Silicon sensor limitations, Industrial sensor applications, Sensor durability, Displacement-force calibration

Deshpande S., Rappel H., Hobbs M., Bordas S., Lengiewicz J.A., Gaussian process regression + deep neural network autoencoder for probabilistic surrogate modeling in nonlinear mechanics of solids, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, ISSN: 0045-7825, DOI: 10.1016/j.cma.2025.117790, Vol.437, No.117790, pp.1-17, 2025

Abstract:
Many real-world applications demand accurate and fast predictions, as well as reliable uncertainty estimates. However, quantifying uncertainty on high-dimensional predictions is still a severely under-investigated problem, especially when input–output relationships are non-linear. To handle this problem, the present work introduces an innovative approach that combines autoencoder deep neural networks with the probabilistic regression capabilities of Gaussian processes. The autoencoder provides a low-dimensional representation of the solution space, while the Gaussian process is a Bayesian method that provides a probabilistic mapping between the low-dimensional inputs and outputs. We validate the proposed framework for its application to surrogate modeling of non-linear finite element simulations. Our findings highlight that the proposed framework is computationally efficient as well as accurate in predicting non-linear deformations of solid bodies subjected to external forces, all the while providing insightful uncertainty assessments.

Keywords:
Surrogate modeling,Deep neural networks,Gaussian proces,Autoencoders,Uncertainty quantification,Finite element method

Włoczewski M., Jasiewicz K., Jenczyk P., Gadalińska E., Kulikowski K., Zhang Y., Li R., Jarząbek D. M., AlCoCrFeNiTi0.2 High-Entropy Alloy Under Plasma Nitriding: Complex Microstructure Transformation, Mechanical and Tribological Enhancement, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-025-07752-1, pp.1-17, 2025

Abstract:
In this study, the AlCoCrFeNiTi0.2 high-entropy alloy (HEA) was plasma nitrided to investigate the microstructure and mechanical properties of high-entropy nitrides formed in the surface layer of the bulk sample. XRD measurements revealed a BCC → FCC crystal structure transformation, with the σ phase disappearing and hexagonal aluminum nitride emerging. Further experimental studies on the nitrided samples, including SEM, EDS, and EBSD, uncovered element segregation into multiple FCC phases with similar lattice constants, such as the NaCl-type (AlCrCoFeNiTi0.2)N high-entropy nitride. These observations align with theoretical analysis based on KKR-CPA calculations. Additionally, plasma nitriding induced high surface porosity; however, micropillar compression testing combined with nanoindentation revealed localized areas with significant hardness. A substantial reduction in the coefficient of friction was also observed. These findings not only provide deeper insights into the nitriding process of complex alloys, like dual-phase HEAs, but also hold promise for further exploration in the manufacturing of super-hard surfaces with high-entropy nitrides, enhancing mechanical properties for applications in harsh environments.

Liu S., Wu J., Teng F., He S., Yuan X., Stupkiewicz S., Wang Y., Effect of surface adhesion characteristics on stick-slip mechanism of flexible film/substrate bilayer structure: Multiscale insight, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2025.110520, Vol.204, pp.110520-1-16, 2025

Abstract:
The key to tactile sensors' sliding perception is the stick-slip modulation of the soft material through surface design. Herein, in-situ sliding tests were conducted on polydimethylsiloxane (PDMS) film/substrate bilayer structures (PF/SBS) with three surface adhesion characteristics tailored by crosslinking degrees of PDMS film. Microscopic damage mechanisms during Schallamach wave propagation were analyzed using mixed-mode cohesive contact models. Intermolecular interaction mechanisms at microscopic crack tips were also explored using PDMS-Silica (SiO2) molecular models with varying PDMS crosslinking degrees. The Schallamach waves and tangential force strongly depended on the crosslinking degree of PDMS film. The varying effects of crosslinking degree on normal and tangential separation mechanisms lead to a transition in Schallamach wave damage from mixed mode to Mode II during propagation.

Keywords:
Stick-slip,Film/substrate bilayer structures,Cohesive contact model,Intermolecular interaction

Darban H., Faghidian S., Flexural frequency analysis of damaged beams using mixture unified gradient elasticity theory, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2025.119143, Vol.363, pp.119143-1-119143-17, 2025

Abstract:
The flexural vibration of miniaturized homogeneous isotropic beams with multiple cracks is investigated using the mixture unified gradient elasticity theory. The model captures both possible stiffening and softening size-dependence at small scales. The problem is addressed using the Bernoulli-Euler beam theory, with the domain partitioned into distinct sections at cracked cross-sections. Cracks are assumed to be non-propagating, sufficiently spaced to avoid interaction, and open during vibration. The elastic spring model is employed to capture the effect of cracks on the dynamic characteristics. The time-dependent variational functional is rigorously established to derive variationally consistent and extra non-standard boundary and continuity conditions. Natural frequencies are obtained by solving the eigenvalue problem resulting from the imposition of boundary and continuity conditions. The predictions demonstrate excellent agreement with experimental, molecular dynamics, and analytical data from the literature for both large- and small-scale beams. The model is applied to examine the effects of gradient characteristic parameters, crack length and location, and boundary conditions on the frequencies. The practical application of the model to the inverse problem, where the location and length of a crack are unknown a priori, is numerically analyzed. The results indicate that the size effect significantly influences the inverse problem solution.

Brachaczek A., Tokpatayeva R., Olek J., Jarząbek D.M., Piotrowski P., Jenczyk P., Jóźwiak-Niedźwiedzka D., Impact of formate based deicing agents on ASR products: Microstructural, chemical and mechanical characteristics, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2025.140729, Vol.471, No.140729, pp.1-12, 2025

Abstract:
This study investigates the effects of formate-based deicing agents, specifically potassium formate (HCOOK) and sodium formate (HCOONa), on alkali-silica reaction (ASR) in concrete. By adapting ASTM C1260 standards, mortar bars were subjected to deicing solutions of varying concentrations to evaluate their influence on mortar expansion and ASR product characteristics. Results revealed that high concentrations of formate solutions significantly accelerated ASR, inducing expansions comparable to or greater than those caused by sodium hydroxide, while sodium chloride showed minimal expansion effects. Microstructural and chemical analyses demonstrated that ASR gels formed in formate solutions were predominantly amorphous, with different chemical composition depending on the deicer type. Pore solution analysis indicated a strong correlation between alkali ion concentration and mortar expansion. Furthermore, mechanical testing of ASR products revealed that gels formed in potassium formate exhibited higher hardness and elastic modulus compared to those formed in sodium formate. These findings enhance understanding of the detrimental effects of formate-based deicing agents on ASR and provide a foundation for developing mitigation strategies to preserve concrete infrastructure.

Keywords:
Alkali-silica reaction,Concrete microstructure,Expansion,Nanoindentation,Deicing agents,Pore solution analysis

Fathalian M., Darban H., Postek E. W., Atomistic insights into tensile damage of functionally Graded Al-SiC composites, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, ISSN: 0020-7403, DOI: 10.1016/j.ijmecsci.2025.110012, Vol.288, pp.110012-1-110012-16, 2025

Abstract:
The tensile behavior and damage mechanisms of functionally graded (FG) Al-SiC composites are systematically investigated using molecular dynamics (MD) simulations. A comprehensive set of large-scale MD simulations is conducted on FG composites composed of three layers reinforced with different volume fractions of randomly distributed three-dimensional SiC particles. This work introduces a novel approach by modeling the reinforcement ceramic as three-dimensional particles, thereby more accurately representing the FG composite microstructure. Predictions of the model for Young's moduli of composites align with experimental data from the literature. The yield and ultimate tensile strength are overestimated due to the high applied strain rates and idealized crystal structures used in the simulations, which lack common defects such as vacancies and dislocations. The model is utilized to study the influence of reinforcement particle shape, size, orientation, and distribution on the tensile and damage behavior of composites. The FG composites reinforced with cubic particles demonstrate lower yield and tensile strength than those with spherical particles, primarily due to the high-stress concentrations around the corners of the cubic reinforcements. Reducing the size of SiC particles enhances the elastic modulus, yield, and tensile strength of the FG composites. It is shown that the stiffness of the FG composites reinforced with rectangular prisms can be effectively tailored by changing the orientation of the reinforcements. When SiC rectangular prisms are aligned along the tensile direction, the resulting FG composites exhibit higher yield and tensile strength. This work offers fundamental atomistic insights that help design FG composites with better mechanical performance.

Rezaee Hajidehi M., Sadowski P., Stupkiewicz S., Indentation-induced deformation twinning in magnesium: Phase-field modeling of microstructure evolution and size effects, Journal of Magnesium and Alloys, ISSN: 2213-9567, DOI: 10.1016/j.jma.2025.02.016, Vol.13, No.4, pp.1721-1742, 2025

Abstract:
Magnesium is distinguished by its highly anisotropic inelastic deformation involving a profuse activity of deformation twinning. Instrumented micro/nano-indentation technique has been widely applied to characterize the mechanical properties of magnesium, typically through the analysis of the indentation load–depth response, surface topography, and less commonly, the post-mortem microstructure within the bulk material. However, experimental limitations prevent the real-time observation of the evolving microstructure. To bridge this gap, we employ a recently-developed finite-strain model that couples the phase-field method and conventional crystal plasticity to simulate the evolution of the indentation-induced twin microstructure and its interaction with plastic slip in a magnesium single-crystal. Particular emphasis is placed on two aspects: orientation-dependent inelastic deformation and indentation size effects. Several outcomes of our 2D computational study are consistent with prior experimental observations. Chief among them is the intricate morphology of twin microstructure obtained at large spatial scales, which, to our knowledge, represents a level of detail that has not been captured in previous modeling studies. To further elucidate on size effects, we extend the model by incorporating gradient-enhanced crystal plasticity, and re-examine the notion of ‘smaller is stronger’. The corresponding results underscore the dominant influence of gradient plasticity over the interfacial energy of twin boundaries in governing the size-dependent mechanical response.

Keywords:
Magnesium alloys, Deformation twinning, Micro/nano-indentation, Microstructure evolution, Phase-field method, Crystal plasticity

Entezari E., Singh A., Mousavisogolitappeh H., Velazquez J., Szpunar J., A cost-effective model for synergistic effects of microstructure and crystallographic texture on hydrogen-induced crack growth and corrosion rates in pipeline steels, Materials Characterization, ISSN: 1044-5803, DOI: 10.1016/j.matchar.2025.114917, Vol.223, No.114917, pp.1-23, 2025

Abstract:
his study proposes a Cost-Effective model based on microstructure, crystallographic texture, and hydrogen (H) diffusion to evaluate H-damage in pipeline steels. H-crack growth and corrosion rates, measured using ultrasonic inspection and a Gamry electrochemical setup, were correlated with microstructure and texture. Results show that smaller ferrite grain size, lower density of co-incidence site lattice boundaries (CSLB), higher densities of geometrically necessary boundaries (GNB) and random high-angle grain boundaries (RHAGB), and higher overall stored energy (EAve) in texture fibers increase H-trap sites and reduce effective H-diffusivity, contributing to higher H-crack growth rates. Conversely, these same factors enhance corrosion resistance by improving passivation. Secondary phases have a detrimental effect on H-crack growth and corrosion resistance, varying with size, continuity, and volume fraction of phases. The proposed model, using hyperparameter tuning, quantifies the synergistic effects of microstructure, texture, and H-diffusion on H-damage and highlights the role of ferrite grain size in mitigating H-damage in pipeline steels. Finally, finite element (FE) analysis of grain structures provided supporting observations.

Keywords:
H-crack growth rate, Corrosion rate, Microstructure, Crystallographic texture, Cost- effective model, Finite element stress analysis

Stupkiewicz S., Amini S., Rezaee Hajidehi M., Twin branching in shape memory alloys: A 1D model with energy dissipation effects, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2025.105671, Vol.113, pp.105671-1-15, 2025

Abstract:
We develop a 1D model of twin branching in shape memory alloys. The free energy of the branched microstructure comprises the interfacial and elastic strain energy contributions, both expressed in terms of the average twin spacing treated as a continuous function of the position. The total free energy is then minimized, and the corresponding Euler–Lagrange equation is solved numerically using the finite element method. The model can be considered as a continuous counterpart of the recent discrete model of Seiner et al. (2020), and our results show a very good agreement with that model in the entire range of physically relevant parameters. Furthermore, our continuous setting facilitates incorporation of energy dissipation into the model. The effect of rate-independent dissipation on the evolution of the branched microstructure is thus studied. The results show that significant effects on the microstructure and energy of the system are expected only for relatively small domain sizes.

Keywords:
Microstructure evolution,Martensite,Twinning,Interfaces,Energy dissipation

Nabavian Kalat M., Ziai Y., Dziedzic K., Gradys A. D., Urbański L., Zaszczyńska A., Andrés Díaz L., Kowalewski Z. L., Experimental evaluation of build orientation effects on the microstructure, thermal, mechanical, and shape memory properties of SLA 3D-printed epoxy resin, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2025.113829, Vol.228, pp.113829-1-18, 2025

Abstract:
Additive manufacturing (AM) methods, popularly known as 3D printing technologies, particularly the pioneering laser stereolithography (SLA), have revolutionized the production of complex polymeric components. However, challenges such as anisotropy, resulting from the layer-by-layer construction method, can affect the thermomechanical properties and dimensional stability of 3D-printed objects. Although anisotropy in SLA 3D printing is often overlooked due to the high precision of this technique, its impact on the properties and structural performance of the 3D-printed prototype becomes more significant when printing small devices designed for precise micro-mechanisms. This experimental study investigates the impact of the chosen printing surface – a less explored factor – on the performance of SLA 4D-printed thermo-responsive shape memory epoxy (SMEp) specimens. Two identical dog-bone specimens were printed from two distinct surfaces: edge and flat surface, to examine how variations in surface area and quantity of layers influence the microstructure, thermal behavior, mechanical properties, and shape memory performance. The results of this experimental investigation reveal that specimens printed from the edge, with a higher number of layers and smaller surface area, exhibit superior interlayer bonding, tensile strength, dimensional stability, and shape recovery efficiency compared to those printed from the flat surface. Conversely, specimens with fewer, larger layers demonstrated greater elongation and thermal expansion but reduced structural integrity and shape recovery performance. These results highlight the importance of experimentally investigating how different build orientations affect the properties and performance of SLA 3D-printed materials, especially before designing and employing them in applications demanding high precision and reliability.

Keywords:
Additive manufacturing, Laser stereolithography, Shape memory polymers, Materials processing, Anisotropy, Printing orientation

Pietrzyk-Thel P., Jain A., Osial M., Sobczak K., Michalska M., Spongy carbon from inedible food: A step towards a clean environment and renewable energy, Electrochimica Acta, ISSN: 0013-4686, DOI: 10.1016/j.electacta.2025.146129, Vol.525, No.146129, pp.1-13, 2025

Abstract:
The global challenges of access to clean water and energy continue to grow, prompting research into sustainable solutions. A promising approach involves the conversion of agricultural waste into high-porosity functional materials for both water purification and energy storage. This study explores the conversion of stale bread into spongy carbon materials, which were evaluated as adsorbents for the removal of cationic dyes and electrodes for supercapacitors. The physical and chemical properties of the material were characterized using standard techniques. In particular, activated carbon produced at 900 °C showed a balanced mixture of micropores and mesopores, with a high specific surface area of ∼1583 m² g-1, making it a low-cost effective adsorbent for the removal of crystal violet dye, showing an adsorption capacity of 753.9 mg g-1, optimal at 10 mg of adsorbent dose with only 10 min of contact time. It performed well in a wide pH range (2–12) and in saline solutions. Furthermore, the material demonstrated a single electrode specific capacitance of ∼155 F g-1, an energy density of 21.6 Wh kg-1, and a power density of 355.9 kW kg-1 in supercapacitor applications. It exhibited high reversibility of charge-storage, retaining ∼85 % of its capacitance after 15,000 cycles. These results highlight the potential of pyrolyzed agricultural waste as a versatile and sustainable material for environmental and energy applications.

Keywords:
Activated carbon, Crystal violet, Dye adsorption, Energy storage application, Supercapacitor

Zhi-Ting H., Lin J., Krajewski M., Poly(vinylidene fluoride-co-hexafluoropropylene) membranes filled with deep eutectic solvent as non-flammable and flexible quasi-solid state electrolytes for high-voltage supercapacitors, Electrochimica Acta, ISSN: 0013-4686, DOI: 10.1016/j.electacta.2025.146192, Vol.526, No.146192, pp.1-13, 2025

Keywords:
Deep eutectic solvent, Gel-like polymer electrolyte, High-voltage supercapacitor, Quasi-solid state electrolyte, Symmetric supercapacitor

Sitek R., Bochenek K., Maj P., Marczak M., Żaba K., Kopeć M., Kaczmarczyk G., Kamiński J., Hot-Pressing of Ti-Al-N Multiphase Composite: Microstructure and Properties, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app15031341, Vol.15, No.1341, pp.1-15, 2025

Abstract:
This study focuses on the development and characterization of a bulk Ti-Al-N
multiphase composite enriched with BN addition and sintered through hot pressing. The
research aimed to create a material with optimized mechanical and corrosion-resistant
properties suitable for demanding industrial applications. The composite was synthesized using a powder metallurgy approach with a mixture of AlN, TiN, and BN powders, processed under a high temperature and pressure. Comprehensive analyses, including microstructural evaluation, hardness testing, X-ray tomography, and electrochemical corrosion assessments, were conducted. The results confirmed the formation of a multiphase microstructure consisting of TiN, Ti₂AlN and Ti₃AlN phases. The microstructure was uniform with minimal porosity, achieving a hardness within the range of 500–540 HV2. Electrochemical tests revealed the formation of a passive oxide layer that provided moderate corrosion resistance in chloride-rich environment. However, localized pitting corrosion was observed under extreme conditions. The study highlights the potential of a BN admixture to enhance mechanical and corrosion-resistant properties and suggests directions for further optimization in sintering processes and material formulations.

Keywords:
AlN-TiN(BN) composite,hot-pressing,μCT,corrosion resistance

Rosowska J., Kaszewski J., Krajewski M., Małolepszy A., Witkowski B. S., Wachnicki Ł., Lev-Ivan B., Sybilski P., Godlewski M., Godlewski M., Growth of ZnO Nanoparticles Using Microwave Hydrothermal Method — Search for Defect-Free Particles, Nanomaterials, ISSN: 2079-4991, DOI: 10.3390/nano15030230, Vol.15, No.230, pp.1-21, 2025

Keywords:
zinc oxide (ZnO) nanoparticles, microwave hydrothermal method , microwave-assisted synthesis, near-band-edge (NBE) emission, deep-level emission (DLE), luminescent properties of ZnO, photoluminescence (PL), cathodoluminescence (CL), defect-related luminescence

Nazir S., Singh P., Rawat N., Jain A., Michalska M., Yahya M., Yusuf S., Diantoro M., Polyether (polyethylene oxide) derived carbon electrode material and polymer electrolyte for supercapacitor and dye-sensitized solar cell, Ionics, ISSN: 0947-7047, DOI: 10.1007/s11581-024-06052-9, pp.1-11, 2025

Abstract:
This study investigates the development and performance analysis of a supercapacitor using activated carbon synthesized from polyethylene oxide (PEO) as the electrode material, and a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer electrolyte, prepared using a solution-cast technique for dye-sensitized solar cell (DSSC) application. This paper deals with polyether-based electrochemical devices, where electrode material is developed by polyethylene oxide (PEO), while an electrolyte is prepared using PVdF-HFP. Detailed electrical and photoelectrochemical studies were carried out using various characterization tools, and the results are discussed in detail. Sandwich structure supercapacitors and DSSCs are developed using maximum conducting polymer electrolyte that has an ionic conductivity of (8.3 × 10−5) Scm−1, exhibiting a high specific capacitance of 395 Fg−1 and DSSC efficiency ranging from 1.6 to 3.5% under 1 sun condition. The findings underscore the capability of PEO-derived carbon and polymer electrolytes in improving the efficiency of energy storage and conversion systems.

Keywords:
Polyether, Activated carbon, Supercapacitor, Dye-sensitized solar cell