Instytut Podstawowych Problemów Techniki

Abstract:
This article aims to explore the potential of using low-cost devices (iPhone and iPad) equipped with LiDAR scanners in the context of measuring the volume of concrete-plastic specimens with complex shapes. The goal was to assess whether these tools can support or even replace traditional metrology methods. For the purpose of the research program concrete-plastic columns with very complex cross-sections (based on different fractals) were harnessed. The research team was focused on analyzing the potential of using this technology to measure the volume of concrete-plastic structural elements created with the help of 3D printing. The tests were conducted under laboratory conditions. The effectiveness of the proposed approach was compared with results obtained using photogrammetry. The challenges of measurement accuracy, the impact of specimen shape, the impact of material and needed optimization of post-processing on the achieved results were also discussed.

Keywords:
3-D printing, LiDAR, Scanning, Fractals, Concrete

Abstract:
This study introduces a spatially distributed diffusion model based on a Navier–Stokes formulation with a pseudo-velocity field, providing a framework for modelling cellular growth dynamics within diseased tissues. Five coupled partial differential equations describe diseased cell development within a two-dimensional spatial domain over time. A pseudo-velocity field mimics biomarker concentration increasing over time and space, influencing tumour growth dynamics. An

Keywords:
Tumour growth, Cellular growth, Cancer, Navier–stokes, Diffusion, Finite element method

Abstract:
Complete fractures of the third metacarpal bone (MC III) diaphysis pose a significant
clinical challenge, prompting advanced veterinary medicine to utilize constitutive and
biomechanical modeling to better understand bone behavior. This study aims to compare
the elastic modulus of the MC III cortical bone, supported by measurements of cortical
bone thickness and relative density, across the dorsal, lateral, medial, and palmar aspects of
the MC III, as well as to evaluate the cortical bone’s response to compressive forces applied
in different directions. Given the bone structure can exhibit sex-related differences, MC III
bones were isolated from six equine cadaver limbs collected exclusively from mares and
imaged using computed tomography (CT) to measure thickness and density. Cortical bone
samples were collected from the four aspects of the MC III and subjected to mechanical
testing followed by the elastic modulus calculation. Bone thickness and elastic modulus
varied across the MC III aspects. Thinner cortical bone on the palmar aspect coincided with
a lower sample reaction force-based elastic modulus in the externo-internal direction and a
lower axial compression force elastic modulus in the proximo-distal direction. Regardless
of the MC III aspect, the cortical bone demonstrated greater resistance to compressive forces
when loaded in the vertical plane than in the horizontal plane. The returning of different
values in mechanical tests depending on the direction of loading may be attributed to
the anisotropic behavior of the cortical bone, which may implicate the increased risk of
complete fractures of the MC III diaphysis due to a kick from another horse or a fall, rather
than from training or competition-related overload.

Keywords:
bone thickness, mechanical test, copression, bending, elastic modulus, equine

Abstract:
This study develops a model of the dynamics of the extended 2D Gao beam and simulates it. Here, the static model studied by Dyniewicz, Shillor and Bajer (Meccanica, 2024), is modified by incorporating inertial terms to account for dynamic behavior. The beam model expands the 1D Gao beam, which can oscillate around a buckled position, and the Timoshenko beam, which factors in shear effects in the beam’s cross sections. The resulting model consists of two highly nonlinear wave equations, alongside specified initial and boundary conditions. A finite element method (FEM) algorithm is created and executed to analyze the system’s vibrations induced by a periodically oscillating longitudinal compressive force. The simulation results are discussed, highlighting the ways the initial conditions influence the solutions, which are graphically illustrated through phase portraits. From an engineering viewpoint, this thick Gao beam model is notable for its relative simplicity. Similarly to the Timoshenko beam model, it includes shear effects, yielding a wave-like equation of motion. Considerations of the shear are essential for accurately analyzing thicker beams, as traditional models that overlook them may fail to capture the true system behaviors. Consequently, this extended Gao model offers more realistic outcomes in dynamic scenarios.

Keywords:
Extended Gao beam, Dynamic oscillations, Vibrations about buckled state, Simulations

Abstract:
Ensuring adequate comfort and safety in vehicle motion is a subject of extensive research worldwide. Despite the implementation of new control algorithms, including those lever-aging AI, the application of effective semi-active vibration dampers remains crucial for achieving optimal suspension performance. This article presents experimental studies conducted on a vehicle equipped with semi-active suspension featuring custom-designed hydraulic dampers controlled by piezoelectric valves. These innovative dampers are characterized by extremely short response times, enabling real-time adaptation to varying driving conditions. A simple control algorithm designed to operate based on real-time signals from suspension sensors is introduced and evaluated. The experimental setup, in-cluding the measurement system used during testing, is described in detail. The presented results highlight the significant potential of this approach for improving driver comfort under specific driving conditions, even without detecting road roughness ahead of the ve-hicle.

Keywords:
semi-active suspension, piezoelectric valve, suspension sensors, ride comfort and safety

Abstract:
A novel magnetorheological (MR) fluid was synthesised by incorporating compressible, nonmagnetic polyurethane microspheres and ferromagnetic iron particles into polyalphaolefin oil. This innovative composition reduces sedimentation, enhances compressibility beyond that of conventional MR fluids, and achieves comparable yield stress with a lower concentration of iron particles. The new MR fluid was evaluated in a prototype translational vibration damper under dynamic conditions across a range of excitation frequencies. The damper’s response with the compressible fluid differed significantly from that observed with non-compressible fluids. Upon activation, the MR fluid increased flow resistance and enhanced the damper’s elastic response, posing unique challenges for further optimisation. Experimental results demonstrate the potential of employing such compressible MR fluids in applications requiring controlled material characteristics.

Keywords:
smart material, magnetorheological (MR) fluid, compressible, microspheres, vibration, damper

Abstract:
The paper states a complex study on the adaptive rescue cushion and concerns a problem of efficient impact mitigation, which is present during evacuation or assurance of people conducted by fire brigades. In order to minimize negative effects of person’s fall from height an airbag system is applied. Unfortunately, until now only passive solutions have been used. As a result, loads acting on a landing person were not minimized, because passive systems are designed for predefined, extreme conditions. Since the authors proposed to introduce adaptation mechanisms into the rescue cushion, a number of issues arose. They include construction and control of release vents, taking into account the inaccuracies of estimated impact parameters, and optimization of the venting area in case the evacuated person lands outside the airbag’s
center. All these problems were addressed within this paper and described in detail. Discussion on the system adaptation and its optimization was preceded by experimental validation of a numerical model. The energy absorbing capabilities of widely used passive rescue cushions were significantly enhanced as a result of the conducted research.

Keywords:
adaptive airbag, Adaptive Impact Absorption, inflatable structure, pneumatic absorber, rescue cushion

Abstract:
The paper examines the potential use of low-cost LiDAR for cave surveying. Mobile mapping using LiDAR complements traditional speleological surveying using a polygonal traverse. These methods assist each other, with one serving as an independent control measurement for the other, ultimately resulting in a more accurate 3D model. The testing results show that achieving high accuracy and detailed cave representation is possible using open hardware and open-source software. Both spacious and well-indented cave sections and narrow passages barely passable by humans were successfully mapped. The surveying process is significantly faster than traditional cave mapping, as drawing cave sketches by hand is unnecessary, being the most time-consuming task on site. This paper also presents a procedure for automated ground plan generation and profile generation from 3D point clouds, further expediting and simplifying the work for speleologists using scanning systems. Also, it is confirmed that the results are reproducible and do not depend on the subjective interpretation of the cartographer, as is the case with traditional speleological drawings.

Keywords:
cave mapping, mobile laser scanning, open hardware, open-source software, cave profiles

Abstract:
Arm-Z is a concept of a hyper-redundant manipulator based on linearly joined sequence of congruent units. Each unit has only one degree of freedom (1-DOF) - the twist relative to the previous unit.
This paper presents the approach to design of modular robotic manipulator based on computer simulations. The approach is rather standard nowadays, however, it is applied to rather unique robotic system. The
CAD model of the module structure for a manipulator with 6 degrees of freedom and respective Denavit-Hartenberg notation are presented. Simulink - a MATLAB-based graphical programming environment was
used to determine the torques of individual modules. The results of three simulations are presented and discussed. Finally, based on critical observations, the drive and gear for the module of Arm-Z system were selected.

Keywords:
Simulation,Robotic arm,Manipulator,Arm-Z,MATLAB Simulink