Apex Angle Research Articles

Study on wetting and spreading behaviors of compound droplets on wedge by lattice Boltzmann method

The wetting and spreading of droplets on solid walls are commonly seen in nature. The study of such a phenomenon can deepen our understanding of solid-liquid interaction and promote the development of relevant cutting-edge technological applications. In this work, the lattice Boltzmann method based on phase field theory is used to investigate the wetting and spreading of a compound droplet on a wedge. This method combines the finite-difference solution of the Cahn-Hilliard equations for ternary fluids to capture the interface dynamics and the lattice Boltzmann method for the hydrodynamics of the flow. Symmetric compound droplets with equal interfacial tensions on a wedge are considered first. Through theoretical analysis and numerical simulation, it is found that the wetted area on the wedge increases with the decrease of the contact angle of the wedge surface and the wedge apex angle. Depending on these two factors, the droplet may or may not split on the wedge. We also find that the droplet near the critical state predicted not to split by static equilibrium analysis could split during the spreading along the wall of the wedge under certain density and viscosity ratios. Based on the simulation results, a phase diagram of the droplet splitting state is generated with the density ratio and viscosity ratio as the coordinates. As the density ratio and kinematic viscosity ratio increase, the inertia effect becomes more prominent in the wetting and spreading process and the droplet is more likely to split. By comparing the phase diagrams in different initial conditions, it is found that under the same conditions, the compound droplet with an equilibrium initial state is less likely to split than that with an unequilibrium initial state, which is possibly because the initial total energy of the former is relatively small. Our study also shows that the kinematic viscosity ratio between the left half and the right half droplet may affect the results of droplet splitting. The increase of such a viscosity difference is conducive to the splitting of the compound droplet. Besides, asymmetric compound droplets with unequal interfacial tensions are also simulated, and it is found that the greater the wrapping degree between the left half and right half, the more difficult it is to separate the compound droplet.

NUMERICAL SOLUTION ON MIXED CONVECTION FLOW OF NANOFLUID AROUND A FINNED ANGULAR SECTOR OF HEAT SINK

The aim of this study is to investigate mixed convection flow of nanofluid around a three-dimensional (3D) finned angular sector of heat sink by means of numerical simulations. The finite-volume method is used to solve the governing equations of mass, momentum, and energy conservation. The Brownian motion of the nanoparticles in the base fluid is explicitly taken into account in the thermal conductivity model (Patel model). A parametric study is carried out to examine the effects of several key parameters on the rate of heat transfer; the angular sector apex angle, the volume fraction of suspended nanoparticles (0 ≤ φ ≤ 0.09), the Richardson number (<i>Ri</i> = <i>Gr/Re</i><sup>2</sup>), and the size of the nanoparticles diameter (5, 20, 60, and 100 nm). It is shown that for a fixed low Richardson number <i>Ri</i>, the rate of heat transfer increases with the volume fraction of the nanoparticles, as forced convection mechanism is dominated. The heat-transfer enhancement is obtained for the nanofluid water/TiO<sub>2</sub> rather than the water/Cu at higher nanoparticles volume concentration and highest Richardson number. Moreover, the Maxwell thermal conductivity model resulted in a maximum enhancement in the case of nanofluid water/TiO<sub>2</sub> than that of water/Cu, whereas the nanofluid water/ Cu gives better heat-transfer enhancement at small particles than that of water/TiO<sub>2</sub>. It is observed too that the nanoparticles' diameter does not have a significant effect on the temperature field.

Experimental Study of Fruit Drying (Italian Bergamot Origin). By Solar Collectors with Variable Baffles in the Shape of a Cone with an Apex Angle of 45°

The application of solar drying by air-air solar collectors to determine air temperature and drying Bergamot is a citrus fruit native to the Mediterranean, well known in Italy in order to sustainably preserve quality such as freshness and flavor, bergamot is a noble fruit and the properties of bergamot are very good for health. A content like many citrus fruits, bergamot has a high content of vitamin C, the antioxidant vitamin par excellence. , which will allow you to boost your immune defenses and fight against winter diseases. Vitamin C also helps fight against oxidative stress responsible for premature aging of cells. Two good reasons to include bergamot in the kitchen among the minerals, useful for fighting against premature ageing. Finally, it is rich in soluble fiber with multiple health benefits. Sun drying for sustainable conservation management from the citrus family, bergamot is a fruit associated with multiple health benefits. It would be good for digestion, for the prevention of cancer, against fatigue or for weight loss. Keywords/ drying bergamot, solar air-air collectors; from Italy, temperature, baffle solar collectors.

Controllable fabrication of Au-nanoprotrusion arrays as a platform for the materials design and characterization

Au-nanoprotrusions (AuNPs) were fabricated on a gold substrate using obliquely incident Ar+ ions with a simultaneous supply of carbon at room temperature. The sputter erosion rate was kept almost constant at 49 nm/min, while the deposition rate of carbon ranged from 1.2 to 0.6 nm/min. Scanning electron microscopy (SEM) observation revealed the variation in the number density and shape of the AuNPs ranging from slender needles to cones with a large apex angle, depending on the carbon deposition rate. Transmission electron microscopy (TEM) demonstrated that the slender needles were characterized by the bi-metal like structure of the large Au grain-rich phase and amorphous carbon phase with a dispersion of fine Au nanoparticles, while the conical structures consisted of Au grains with an amorphous carbon cap region on top. Those structures were selectively prepared, depending on the application. Li-C nanocomposite films deposited on conical structures, for instance, were readily observed cross-sectionally by TEM without any post treatment, revealing the instantaneous formation of a solid electrolyte interphase (SEI) after only 2 charge-discharge cycles in the cyclic voltammetry (CV) measurement. Thus, AuNPs are promising as a platform for the materials design and characterization in atomic dimensions.

Effect of a Conical Cellulose Structure on Horseradish Peroxidase Biomacromolecules

The effect of a dielectric conical structure on the adsorption properties of an enzyme on mica was studied by atomic force microscopy (AFM) with the example of horseradish peroxidase (HRP). The cone used was a cellulose cone with a 60° apex angle. Namely, AFM allowed us to reveal an increase in the enzyme’s aggregation during its adsorption onto mica from the solution incubated near the cone apex for 40 min—as compared with the control enzyme samples incubated far away from the cone. In contrast, no change in the HRP adsorption properties was observed after shorter (10 min) incubation of the sample near the cone. The enzymatic activity of HRP was found to be the same for all the enzyme samples studied. Our findings should be considered upon designing biosensors (in particular, those intended for highly sensitive diagnostic applications) and bioreactors containing conical structural elements. Furthermore, since HRP is widely employed as a model enzyme in studies of external impacts on enzymes determining food quality, our data can be of use in the development of food-processing methods based on the use of electromagnetic radiation (microwave treatment, radiofrequency heating, etc.).

Effect of sagittal screw angle and distance of screw apex to superior endplate on adjacent segment disease after posterolateral lumbar fusion: a retrospective study

BackgroundNumerous complications of lumbar fusion surgery have been reported, with adjacent segment disease (ASD) being one of the most important. Few studies describe the effect of sagittal, horizontal screw angles and distance of pedicle screw apex to superior endplate on the incidence of ASD in lumbar spine. The purpose of this retrospective study is to evaluate the hypothesis that unsatisfactory pedicle screw insertion positions would increase the likelihood of ASD.MethodsOutpatients with lumbar spinal stenosis underwent posterolateral lumbar fusion at L4-S1 with a least 2-year follow-up were studied. ASD at L3–L4 was defined as a condition in which intervertebral disk narrowing, posterior vertebral opening, and vertebral slippage progress at the last follow-up in comparison with the postoperative. Independent t test was performed to compare data between two groups; Spearman analysis was performed to analyze the relationship between two continuous variables. Multivariate binary logistic models were performed to identify the independent risk factors of ASD. The receiver operating characteristic (ROC) curve was performed to measure model discrimination and Hosmer–Lemeshow (H–L) test was used to measure calibration. ROC curve evaluated the discrimination ability of sagittal screw angle and distance in predicting incidence of ASD.ResultsPatients in ASD group exhibit higher incidence of osteoporosis, higher Visual analogue scale (VAS), Oswestry disability index (ODI), bigger sagittal screw angle, shorter distance of pedicle screw apex to superior endplate than those in non-ASD group (p < 0.05). VAS, ODI at the last follow-up were positively correlated with Pfirrmann grade of L3–4 disk and sagittal screw angle, while negatively correlated with distance of screw apex to superior endplate (p < 0.05). Multivariate binary logistic model indicated that follow-up time (odds ratio [OR] 1.637, 95% confidence interval [CI] 1.186–2.260), distance of screw apex to superior endplate (OR 0.150, 95% CI 0.067–0.336), sagittal screw angle (OR 2.404, 95% CI 1.608–3.594) were statistically significant. The models showed great discrimination and calibration. The area under the curve of ASD identified by sagittal angle and distance was 0.895 and the cut-off values were 5.500° and 6.250 mm, respectively.ConclusionSagittal screw angle and distance of screw apex to superior endplate were significantly associated with the risk of ASD.

Driven translocation of a semiflexible polymer through a conical channel in the presence of attractive surface interactions

We study the translocation of a semiflexible polymer through a conical channel with attractive surface interactions and a driving force which varies spatially inside the channel. Using the results of the translocation dynamics of a flexible polymer through an extended channel as control, we first show that the asymmetric shape of the channel gives rise to non-monotonic features in the total translocation time as a function of the apex angle of the channel. The waiting time distributions of individual monomer beads inside the channel show unique features strongly dependent on the driving force and the surface interactions. Polymer stiffness results in longer translocation times for all angles of the channel. Further, non-monotonic features in the translocation time as a function of the channel angle changes substantially as the polymer becomes stiffer, which is reflected in the changing features of the waiting time distributions. We construct a free energy description of the system incorporating entropic and energetic contributions in the low force regime to explain the simulation results.

Wave Diffraction by Metamaterial-Coated Wedges: The UAPO Solution for Skew Incidence

The interaction between an electromagnetic plane wave and a metallic wedge coated with a uniform layer made of a double-negative metamaterial is studied by means of the uniform asymptotic physical optics method in the high-frequency range, e.g., at microwave and optical frequencies. The apex angle of the structure is arbitrarily chosen, and the wave is at a skew incidence with respect to the external edge, which is formed by the metamaterial layers covering the wedge faces. The proposed method is built on the scattering integral involving electric and magnetic surface currents as physical optics equivalent sources, and it takes advantage of analytic evaluations. The last step uses a uniform asymptotic procedure to obtain a closed form expression of the diffracted field to be added to the geometrical optics one for computing the total field at the observation point in the neighboring free space. The study also includes a numerical validation of the method.

Electrically controlled continuous laser beam steering in a liquid crystal based electro-optic waveguide

Non-mechanical and continuous beam steering devices are highly desirable in recent laser scanning applications and telecommunication advancements. We report a liquid crystal (LC) core waveguide-based electrically controlled, non-mechanical, and continuous laser beam steering device. The waveguide uses nematic 5CB (4-cyano-4′-pentylbiphenyl) LC as a propagation medium surrounded by PVA (polyvinyl alcohol) polymer cladding, which is realized on ITO coated glass substrates. A pattern of five triangular electrodes is transferred on the substrate using photolithography to create prisms of tunable refractive index in the LC core of the waveguide. The beam steering for transverse electric (TE) and transverse magnetic (TM) polarization is theoretically studied and experimentally characterized using a He-Ne laser of λ = 633 nm. A steering angle of −5.4° and +5.7° at 7 Vpp is obtained for TE and TM polarization, respectively, in a waveguide with the prism’s apex angle of 13°. Similarly, a higher steering angle up to 7.3° for TM polarization is demonstrated in the waveguide with an apex angle of 22°. The device is developed using ease of fabrication process and cost-effective materials that operate at relatively low voltages.

Scoliosis assessment tools to reduce follow-up X-rays.

PurposeClinical examinations of scoliosis often includes X-rays. Regular clinical monitoring is recommended in particular at young age, because of the high risk of progression during periods of rapid growth. Supplementary methods free of ionizing radiation thus could help to reduce the potential risk of ionizing radiation related health problems.MethodsTwelve 3D scan images from female and male patients with different types and severities of spinal deformations were analysed using body scanner image analysis tools. The scan images were captured with a 3D body scanner, which used an infrared sensor and a video camera. To calculate and compare with the patient's specific spinal deformations, simulations based on finite elements methods were performed on biomechanical models of ribcage and spinal column.ResultsThe methods and parameters presented here are in good agreement with corresponding X-rays, used for comparison. High correlation coefficients of ‖ρs‖ ≥ 0.87 between Cobb angle and lateral deviation, as well as between Cobb angle and rotation of the vertebrae, indicate that the parameters could provide supplementary informations in the assessment of spinal deformations. So-called apex angles, in addition introduced to relate the results of the present method with Cobb angles, show strong correlations of ‖ρs‖ ≥ 0.68 and thus could be used for comparison in later follow-up examinations.ConclusionThe user-friendly 3D body scanner image analysis tools enable orthopaedic specialists to simulate, visualize and inspect patient's specific spinal deformations. The method is intended to provide supplementary information in complement to the Cobb angle for the assessment of spinal deformations in clinical daily routine and might have the potential to reduce X-rays in follow-up examinations.The Translational Potential of this articleThe study presents a new method, based on 3D body scanner images and biomechanical modelling, that has the potential to reduce X-rays when monitoring scoliosis especially in young patients.

Geometrical model establishment and preoperative evaluation on A-T flap design: Finite element method-based computer-aided simulation on surgical operation processes.

ObjectiveA-T flap has been extensively applied to repair dermal soft tissue defects. The flap design completely depends on the experience of doctors. Herein, we explored the approach of analyzing the reasonability of A-T flap design and performed a simulation of operation processes by computer-aided technology. Afterward, the finite element analysis software (MSC.Marc/Mentat) was used to establish the simulation model, based on which the computer simulation of flap suturing and release state in A-T flap surgery was performed.MethodsA geometrical model of the A-T flap was established, and the length-width ratio of the flap, maximum suture distance, and suture area that could influence the postoperative suture effects of the flap were analyzed. The reasonable surgical planning for A-T flap design based on the crossing constraint relationship was achieved. The simulation model was established by the finite element analysis software (MSC.Marc/Mentat), based on which computer simulation of flap suture and release state of A-T flap in surgery processes were performed. The flap’s stress and deformation distribution results confirmed the applicability of the A-T flap design method proposed in the present study.ResultsWhen the apex angle of the A-T flap was 60 degrees, the suture area was the smallest, and the flap design had the highest practicability.ConclusionComputer-assisted preoperative assessment, which has high clinical value, could provide a theoretical basis for A-T flap design in clinical practice.

Ejection velocities, age, and formation process of SPE meteoroid cluster

Context. Meteoroid clusters represent a unique opportunity to study processes of meteoroid disruptions in interplanetary space. We follow our previous work about the September epsilon Perseid (SPE) meteoroid cluster from 2016 with a detailed analysis of the observed data and cluster formation conditions. Aims. Our goal is to determine ejection velocities of the cluster members and SPE’s age, as well as to estimate the most probable formation process. Methods. We precisely determined mutual positions and masses of all meteoroids including the errors. We assumed that the massdominated meteoroid is the parent body of the cluster and that the observed positions of meteoroids are controlled by the ejection velocities and the action of solar radiation pressure. A formula for the dependence of meteoroid ejection velocities on the mutual positions, masses, and cluster age was derived. It was assumed that the time at which the initial kinetic energy of all meteoroids reached a minimum value corresponds to the age of the cluster. Knowing values and directions of ejection velocities together with meteoroid masses then allowed us to determine the most likely process of cluster formation. Results. The meteoroids occupy a volume of 66 × 67 × 50 km and are shifted in the antisolar direction by 27 km relative to the parent meteoroid. The age of the cluster is 2.28 ± 0.44 days. The ejection velocities range from 0.13 ± 0.05 m s−1 to 0.77 ± 0.34 m s−1 with a mean value of 0.35 m s−1. The ejection velocity directions are inside the cone with an apex angle of 101 ± 5°. The axis of the cone is ~45° away from the solar direction and ~34° away from the mean direction of the flux of small meteoroids’ incident on the parent meteoroid. Formation due to the separation of part of the surface due to very fast rotation is the least likely thing to occur. We estimate the rotation frequency to be about 2 Hz and the corresponding stress is several orders of magnitude lower than the predicted strength limit. It is also difficult to explain the formation of the cluster by an impact of a small meteoroid on the parent body. However, this possibility, although not very likely, cannot be completely ruled out. The most probable process is the exfoliation due to thermal stresses. Their estimated magnitude is sufficient and the derived ejection velocities are consistent with this process of formation.

Analyzing ballistic impact of bullet over laminated test specimen

Impact analysis of an object over a test specimen is a major design related aspect related to toughness of the material. Based on review, different parameters affecting the ballistic impact were analyzed. Parameters having a major effect on impact were found to be apex angle, thickness, and composite material parameters. A projectile impact of bullet on laminated test specimen was carried experimentally and simulated with explicit dynamics approach using Ansys®. The bullet shears certain amount from laminated test specimen on impact and passes out. The ballistic limit of laminated test specimens of varied thickness was analyzed for projectiles with 7.6 AP against oblique and normal impact. Projectile's experienced resistance is seen to be greater with greater conical portion's surface area in contact with target.

Comparative morph-anatomical leaf characters of Mentha spicata and Ocimum basilicum family (Laminaceae) in Sudan

The objects of the studies reports the morphology and anatomy of the leaves of two well-known medicinal plants in Sudan; Menthaspicata and Ocimum basilicum family Lamiaceae (labiaceace), Morphologically, the two studied species have leaves apex acute with simple leaves and pinnate venation leaves. Leaf margin, leaf base, leaf color and radar shape for leaf length, leaf width, leaf base angle and leaf apex angle and leaf base angle showed that these characters are correlated for each species. Anatomically, the two species have stomata dicytic type stomata and have midrib Collenchyma one layer and parenchyma 3 layers below the upper epidermis Collenchyma 1-2 layer and 5-6 layers parenchyma above the lower epidermis. Mentha spicata lamina showed the upper epidermal cells are polygonal of different sizes, stomata appeared, the epidermal hairs appeared, peltate scale-simple hairs-glandular trichomes, mesophyll the leaf is dorsiventral formed of palisade layers and spongy parenchyma, below the upper epidermis is palisade layer, above the lower epidermal is spongy parenchyma. Ocimum basilicum.L Showed also lamina upper epidermal cells are formed of polygonal cells of small sizes, interrupted by stomata, mesophyll the leaf is dorsiventral, (palisade cells are small in size).

Free vibration analysis of a porous functionally graded, truncated conical shell with a magneto-rheological fluid core

Vibration absorbers are vital to resisting shocks in many structures. This study analyzed the effects of magnetic field, porosity and geometry on the natural frequency and loss factor of a conical shell made of smart porous materials. Natural frequency declined when the length, radius and thickness ratios increased. The loss factor and porosity coefficients increased concurrently. The magnetic intensity had little effect on the natural frequency. Increasing the apex angle or porosity, raised the loss factor but reduced the natural frequency. Raising the core’s top layer thickness reduced the natural frequency but increasing the L/R1 or R1/h ratio reduced the frequency.

Leaf Characterizations of IRR 400 Series, BPM 24, and RRIC 100 Rubber (Hevea brasiliensis Muell. Arg.) Clone Using Leafgram Method

Leaf characterization of rubber clones needs to be done from the start, especially for plants in the budwood garden. This function is to produce genetically pure and original plants. The purpose of this study was to characterize the IRR series 400, RRIC 100, and BPM 24 clones based on leaf character using the leafgram method. The types of clones that were characterized were IRR 425, IRR 428, IRR 429, IRR 434, IRR 440, RRIC 100, and BPM 24. The leaves characterized were the middle leaves of each clone as many as 50 leaves per clone, divided into three replications. The leaf characters observed were length, width, top fold point, center point, left strand, large, apex angle, vein angle, basal angle, apex kite angle, basal kite angle, ratio length/width, ratio length/top fold point, ratio left strand/large/ ratio left strand top fold point, ratio left strand/center point, ratio top fold point/large, ratio top fold point/center point, ratio apex/basal angle, ratio vein/apex angle, ratio vein/basal angle and ratio apex kite/basal kite angle. Data were analyzed using MINITAB 16 software and Microsoft Office 2010. The characterization results showed that the distinguishing characters that can be used as characteristic of characters are width, left strand, apex angle, basal angle, ratio length /width, ratio left strand/top fold point, ratio left strand ratio/center point, ratio top fold point/large, ratio apex/basal angle, ratio vein/apex angle, and ratio vein/ basal angle.

Heat transfer characteristics of jet impingement onto the concave surface of a cone

ABSTRACT Heat transfer coefficient measurements for jet impingement onto the concave surface of a cone with apex angles equal to 30° and 70° are reported in this study. Static pressure measurements along the cone surface are also reported which aid in explaining the results from the heat transfer measurements. The conical geometry finds application for the heating of aircraft gas turbine engine nose bullet region which could experience ice formation whenever aircraft operates at higher altitudes. The concave surface of the cone is heated by impinging hot air tapped from the compressor. The heat transfer coefficients, which are significantly different compared to flat surface impingement, and are scarcely available, are reported in this study. The influence of the jet axis coincident with the cone axis and impinging into apex region was studied first. The methodology where a thin stainless-steel foil is heated with a known heat flux by passing electric current through it and then measuring the detailed surface temperature using an infrared thermal camera, was used to compute the wall Nusselt distribution. The Nusselt number variation is presented as a function of nondimensional apex to nozzle spacing (L/D) and the nondimensional axis displacement (O/D). Three different diameter (D equal to 10 mm,14 mm and 20 mm) pipes were used for the concentric impingement case and the Nusselt number distribution was observed not depend on the injection diameter. The jet Reynolds number was varied between 25000 and 82000. The peak Nusselt number values are similar to those for flat plate impingement and do not occur at the cone apex, but at a nondimensional distance between 3.2 and 3.9 for 4.25 < L/D < 10.25 for the 30° cone. The peak Nusselt number values increase by almost 30% with decrease in the L/D from 10.2 to 3.0. Wall static pressure measurements indicated that the peak Nusselt number values occur in regions where the interaction between the incoming and outgoing streams is strongest – these regions occur at distances downstream from the stagnation region toward cone exit. The peak heat transfer coefficient location could not be obtained for the 70° cone, but the measured maximum values are higher by 30–50% compared to those for the 30° case. The jet is able to penetrate further toward the apex of the cone for 70° cone compared to 30° cone shifting the peak heat transfer locations closer to the apex for larger apex angle case. There is insignificant influence of jet diameter on Nusselt number variation for the three diameter values investigated in this study. The influence of displacing the jet axis by a distance equal to half the jet diameter in a direction perpendicular to the cone axis was also studied but detailed measurements were possible only for the 30° cone. Two semi-circular regions, one close to the impingement tube and the other away from the tube, displaying similar heat transfer coefficient behavior were observed. A peak in the Nusselt number occurs in each semi-circular region and the magnitude of the peaks are nearly same and they lie on either side of the peak location observed for the concentric impingement case when the flow geometric parameters are similar for the two cases. The measurements for the 70° cone exhibited all features of the 30° cone but the maximum values were higher by nearly 40% for this case.

The dilatation line in an elastic wedge

A solution for a dilatation line which occupies an arbitrary position in an elastic wedge with free surfaces and an arbitrary apex angle is found for the first time. The analytical expressions are given in the Mellin space for the stress fields of the dilatation line. It is shown that the free surfaces of the wedge strongly affect upon the stress fields. The axial and hydrostatic stress components are not equal to zero outside the dilatation line. They are strongly inhomogeneous and can change their signs, while their magnitude is comparable with that of the other non-vanishing stress components. They also demonstrate strong non-monotonic and alternating dependence on the wedge apex angle. For the wedge apex angles of 180° and 360°, the non-vanishing stress components of the dilatation line are represented in an explicit form. The results obtained can be used for solving similar problems for long elastic dilatation inclusions of arbitrary cross section embedded to wedge-shaped elastic bodies. The paper is devoted to the memory of our friend and colleague Igor Sevostianov who gave a great contribution to micromechanics of composite and porous materials.

Crashworthiness performance of thin-walled hollow and foam-filled prismatic frusta – FEM parametric studies – Part 1

Structural members termed frusta (conical shells or tapered prismatic tubes) are used as energy absorbers due to the stable plastic behavior during axial crushing process and to the decrease of peak crushing load in comparison with cylindrical columns or parallelepiped-shaped​ thin-walled columns. The paper presents the parametric study into crashworthiness performance of prismatic steel thin-walled frusta of square base and various apex angles produced from two face to face channel section bars, both hollow and foam filled, subjected to axial impact load. Material used for filled frusta was the polypropylene foam. An influence of geometrical parameters : wall inclination angle (frustum apex angle), wall thickness and frustum height as well as influence of foam filling on energy absorption and crashworthiness performance is investigated. The parametric study is performed using Finite Element simulations. Two step analysis was carried out (the eigenvalue buckling analysis and subsequently the non-linear explicit dynamic analysis). Crushing behavior (buckling and failure modes) and load–shortening characteristics obtained on the basis of FE numerical results are discussed. Energy absorbing effectiveness is analyzed using crashworthiness indicators, namely Peak Crushing Force (PCF), Crash Load Efficiency (CLE) and Total Efficiency (TE). Effect of synergy in case of foam filled frusta is examined. On the basis of the analyses some conclusions are derived concerning the most effective configurations of geometrical parameters of frusta under investigation as well as some of the drawbacks and limitations of the applicability of indicators used in the analysis. Further research topics are presented, including an identification of new or modified crashworthiness indicators and multi-objective optimization of examined frusta.

Influence of the Geometrical Features of the Cutting Edges of Abrasive Grains on the Removal Efficiency of the Ti6Al4V Titanium Alloy.

The shape of the cutting blades of the abrasive grains has an influence on the material separation process in the machining zone. The paper analyzes the influence of the geometrical parameters of the abrasive grains (rake angle γ, apex angle ε, opening angle α), as well as width bz and length bb of the cutting zone on the material removal efficiency. The material removal efficiency was determined taking into account the volume of the removed material VG and the volume of lateral piles-up VR. The analyses were carried out on the basis of the results of experimental and simulations using the finite element method. The relationship between the selected geometric parameters characterizing the cutting zone and the coefficient characterizing the efficiency of the material removal process was determined. A strong influence of the opening angle α as well as the width bz and length bb of the cutting zone on the material removal process by abrasive grain was demonstrated. It was observed that the wide cutting edge, and thus the large opening angle α of the grain, reduced the size of the pile-ups and more effectively removed the chip material.