Minimum Coefficient Research Articles

Micromechanical and Tribological Characterization of Fabricated Ti–6Al–4V Alloy Using Laser Powder Bed Fusion

Abstract In the dynamic era of advanced manufacturing technology, laser powder bed fusion (L-PBF) have gained popularity in different domains due to its capability to build parts from bulk to miniature size with higher efficiency and precision. Ti–6Al–4V, a bio-inert metal alloy, possesses a unique blend of profound mechanical and biocompatibility attributes, making it highly suitable for implant applications. This study reports the fabrication of Ti–6Al–4V alloy for implant application via the L-PBF process. The objective is to enhance the micromechanical and tribological properties of the fabricated Ti–6Al–4V component by identifying the optimal processing conditions. The fabricated component exhibited a maximum hardness of 395.26 HV and a minimum frictional coefficient of 0.3193 at 195 W laser power, 900 mm/s scanning speed, and 70 μm hatching distance. The wear-rate and absorbed wear volume were measured as 1.265 × 10−5 mm3 N−1 min−1 and 0.3162 mm3, respectively, under sliding conditions. At optimal processing state, the printed surface displayed an alpha-phase morphology with homogeneous microstructural features due to uniform melting of powder particles that improved bond strength and minimized defects. This study offers an experimental insight into operational attributes, paving the way for accelerated production of Ti–6Al–4V alloy components using the L-PBF method and tailoring tribological properties to meet specific functional requirements.

Stair-Climbing Wheeled Robot Based on Rotating Locomotion of Curved-Spoke Legs.

This study proposes a new wheel-leg mechanism concept and formulations for the kinematics and dynamics of a stair-climbing robot utilizing the rotating leg locomotion of curved spokes and rolling tires. The system consists of four motor-driven tires and four curved-spoke legs. The curved-spoke leg is semicircle-like and is used to climb stairs. Once the spoke leg rolls on the surface, it lifts and pulls the mating wheel toward the surface, owing to the kinematic constraint between the spoke and the wheel. Single-wheel climbing is a necessary condition for the stair climbing of whole robots equipped with front and rear axles. This study proposes the design requirements of a spoke leg for the success of single-wheel climbing in terms of kinematic inequality equations according to the scenario of single-wheel climbing. For a design configuration that enables single-wheel climbing, the required minimum friction coefficient for the static analysis of the stair-climbing wheeled robots is demon-strated. Thereafter, the stair-climbing ability is validated through the dynamic equations that enable the frictional slip of the tires, as well as the curved-spoke legs. Lastly, the results revealed that the rotating locomotion of the well-designed curved-spoke legs effectively enables the stair climbing of the whole robot.

Absorption Measurement in Ultrapure Crystalline Quartz with the Eliminated Influence of Ambient Air Absorption in the Time-Resolved Photothermal Common-Path Interferometry Scheme

We demonstrate measurements of the absorption coefficient α ≈ 2.5 × 10−7 cm−1 in synthetic crystalline quartz at a wavelength of 1071 nm with a signal-to-noise ratio of 10/1 using the Time-resolved photothermal common-path interferometry (TPCI) scheme. It utilized cells filled with flowing argon and eliminated the influence of ambient air absorption. The scheme elements limiting the sensitivity of measurements at the level of ≈7.8 × 10−8 cm−1 were revealed. When these elements are replaced by better ones in terms of their thermal influence, the sensitivity of absorption coefficient measurements in crystalline quartz is ~10−8 cm−1. The calculation of the correction due to these optical elements of the values of the measured absorption coefficients is also described, which makes it possible to achieve the same sensitivity without replacing the elements. The improved scheme confirms the presence of the spatial inhomogeneity of absorption with a minimum coefficient of 2.5 × 10−7 cm−1 in synthetic crystalline quartz. The discrepancy of the absorption coefficient values in different regions of the crystal in the presented series of experiments was 2.5 × 10−7 cm−1 to 4 × 10−6 cm−1. Taking into account the ratio of thermo-optical parameters and the heat diffusion effect, the calculation shows that for quartz glasses the corresponding sensitivity of the absorption coefficient measurements equals ≈1.5 × 10−9 cm−1.

Assessing and mitigating building fire risk based on the scenario clusters in Bangladesh

The increasing occurrence of fire hazards in residential buildings in Bangladesh has led to severe property damage, physical injuries, and fatalities, underscoring a critical research gap in effective fire risk management. This study aims to address this gap by identifying key fire risks and proposing mitigation strategies using BIM technology. The research employs a comprehensive survey and scenario clustering methodology to identify these risks and assess the efficacy of various fire-resistant materials. Data collection involved questionnaires distributed to 200 respondents, including building owners, occupants, engineers, and firefighters. These clusters are based on the metrics of fatality numbers and property damage to quantify fire risk. Findings highlight the significant role of wall and ceiling lining materials (RII = 0.919) in contributing to fire risk. Further analysis was conducted using a residential building model developed in Autodesk Revit and simulated in Pyrosim software, assessing various lining materials. Quantitative results demonstrated that fire brick is the most effective material, exhibiting the lowest heat release rate (968 kW/m2), minimum adiabatic surface temperature (28°C), minimum heat transfer coefficient (1.75 W/m2/K), and lowest surface burning rate (7.5e−08 Kg/m2/s). These results suggest that fire brick is the optimal choice for enhancing fire resistance in residential buildings.

Using Thin Ultra-High-Molecular-Weight Polyethylene Coatings to Reduce Friction in Frost-Resistant Rubbers.

Frost-resistant rubbers retain their highly elastic properties over a wide temperature range. They are used in various friction units (e.g., seals), but their high friction coefficient and low wear resistance lead to the need for frequent replacement. In this paper, we propose applying thin (several hundred microns) UHMWPE coatings to formed rubber rings. The application technology depends on the required coating thickness. Friction tests of the coatings and pure UHMWPE were performed using the ball-on-disk (unidirectional sliding) scheme for various loads and velocities. In the experiments, the friction coefficients and temperatures near the contact area were determined. Friction tracks were studied using microscopy methods. The sliding contact of the ball and the two-layer material was modeled to obtain the dependences of the deformation component of friction on the sliding velocity for coatings of different thicknesses. UHMWPE is sensitive to frictional heating, so the thermal problem of determining the temperature in the contact area was also solved. It is shown that the minimum friction coefficient occurs for coatings with a thickness of 600 μm. At the same time, in the case of the 300 μm coating, the surface of the friction track is practically no different from the initial one. Thus, the studied combination of polymers provides antifrictional properties and wear resistance to the surface layer while maintaining the damping properties of rubber.

Exergetic characterization of flat plate solar collector using genetic algorithm

With the rapid advancement of technology, the global demand for energy is increasing exponentially. It is crucial to focus on energy conservation and conversion across all sectors. This study conducted a second law or exergy analysis on a solar water heating system to uncover hidden losses during the process. To optimize exergetic efficiency, a genetic algorithm was employed to control the overall loss coefficient of a solar flat plate collector. Four decision variables were used in the genetic algorithm—heat flux rate, glass cover temperatures at the inlet and exit, and collector plate temperature to minimize the overall loss coefficient. Energy efficiency, entropy generation, and exergy destruction were estimated for various mass flow rates using thermodynamic equilibrium equations. Exergy correlations were developed concerning mass flow rate (0.001–0.009 kg/s), inlet temperature (300 K–360 K), collector plate area (1–10 m²), incident solar energy (400–900 W/m²), optical efficiency (0.4%–1%), and ambient temperature (300–315 K) under a range of initial conditions. It was found that exergy efficiency slightly increased (0.01%–0.08%) over a 12-h period. Although this increase is small, it can significantly contribute to energy conservation over the long term. The genetic algorithm predicted the minimum loss coefficient occurring during peak hours (12–14 p.m.) with respect to four decision variables. The results of this study were compared with existing literature and showed good agreement. In addition to the exergy analysis, an uncertainty error analysis was performed to assess the reliability and accuracy of the experimental measurements and computational predictions. By quantifying these uncertainties, the study ensured that the reported enhancements in exergy efficiency and the optimization results obtained through the genetic algorithm are robust and credible. This rigorous error analysis adds confidence to the findings, highlighting the potential for improved energy conservation in solar water heating systems.

Aerodynamic and acoustic evaluation of a cylinder covered by stretched grooved fabric near critical Reynolds numbers

This study investigates aerodynamic drag and acoustic noise generated from a circular cylinder by wrapping longitudinally grooved fabrics. The fabrics are stretched to different levels to explore their potential for flow and acoustic control near critical Reynolds numbers. To analyze the fabrics' surface characteristics, 3D scanning and several microscopic techniques were employed. The parallel-mounted load cells and an array of microphones were used to measure the drag and noise at Reynolds numbers, based on cylinder diameter, ranging from \num{3.3e4} to \num{1.1e5} in an anechoic wind tunnel. Additionally, hotwire anemometry was used to examine the wake structures in the vicinity of the cylinder. The surface scanning results revealed that stretching the fabric transversely to twice its original size reduced the groove depth by approximately $54\%$ and increased the width by around $25\%$, resulting in an overall reduction of the arithmetic surface roughness $S_a$ by $18.6\%$. Based on the wind tunnel data, it was observed that a grooved fabric with higher stretch, and thus lower surface roughness exhibited a minimum drag coefficient at a higher Reynolds number, along with reduced acoustic tonal noise levels.

Effect of laser remelting on microstructure evolution and high-temperature fretting wear resistance in a laser-cladding self-lubricating composite coating on titanium alloy substrate

TC21 titanium alloy possesses the advantage including high strength, low density, and great resistance to damage. Combining it with surface modification technology, it is expected to improve the performance of aviation structural components. This work applied laser remelting technology to realize surface modification, and the hardness and fretting wear properties of the coating were investigated. This research has found that laser remelting technology can effectively refine grain size and improve the performance of coatings. By exploring different laser remelting powers (600 W, 900 W, 1200 W) and the different diameters of laser beam (3 mm, 6 mm), the optimal laser process was obtained with laser power and spot diameter of 600 W and 6 mm, respectively. The average grain size is 2.1 μm. The laser remelting coating has an average microhardness about 980 HV0.2, and it is 2.5 times and 1.3 times higher than the substrate and laser cladding hardness, respectively. A minimum coefficient of friction (COF) about 0.5 was obtained by the laser remelting coating, and the wear rate reaches the lowest of 1.87 × 10−6 mm3/(N·m) at fretting temperature with 500 °C. The abrasive wear and adhesive wear were the main wear mechanisms, and accompanied by oxidative wear. This study provides important reference for improving the performance of high-strength titanium alloy to obtain low defect, high-performance coatings with stable quality.

Characterization and Growth Kinetics of Borides Layers on Near-Alpha Titanium Alloys.

Pack boriding with CeO2 was performed on the powder metallurgical (PM) near-α type titanium alloy at a temperature of 1273-1373 K for 5-15 h followed by air cooling. The microstructure analysis showed that the boride layer on the surface of the alloy was mainly composed of a monolithic TiB2 outer layer, inner whisker TiB and sub-micron sized flake-like TiB layer. The growth kinetics of the TiB2 and TiB layers obeyed the parabolic diffusion model. The diffusion coefficient of boron in the boride layers obtained in the present study was well within the ranges reported in the literature. The activation energies of boron in the TiB2 and TiB layers during the pack boriding were estimated to be 166.4 kJ/mol and 122.8 kJ/mol, respectively. Friction tests showed that alloys borided at moderate temperatures and times had lower friction coefficients, which may have been due to the fine grain strengthening effect of TiB whiskers. The alloy borided at 1273 K for 10 h had a minimum friction coefficient of 0.73.

Experimental Study of Surface Microtexture Formed by Laser-Induced Cavitation Bubble on 7050 Aluminum Alloy

In order to study the feasibility of forming microtexture at the surface of 7050 aluminum alloy by laser-induced cavitation bubble, and how the density of microtexture influences its tribological properties, the evolution of the cavitation bubble was captured by a high-speed camera, and the underwater acoustic signal of evolution was collected by a fiber optic hydrophone system. This combined approach was used to study the effect of the cavitation bubble on 7050 aluminum alloy. The surface morphology of the microtexture was analyzed by a confocal microscope, and the tribological properties of the microtexture were analyzed by a friction testing machine. Then the feasibility of the preparation process was verified and the optimal density was obtained. The study shows that the microtexture on the surface of a sample is formed by the combined results of the plasma shock wave and the collapse shock wave. When the density of microtexture is less than or equal to 19.63%, the diameters of the micropits range from 478 μm to 578 μm, and the depths of the micropits range from 13.56 μm to 18.25 μm. This shows that the laser-induced cavitation bubble is able to form repeatable microtexture. The friction coefficient of the sample with microtexture is lower than that of the untextured sample, with an average friction coefficient of 0.16. This indicates that the microtexture formed by laser-induced cavitation bubble has a good lubrication effect. The sample with a density of 19.63% is uniform and smooth, having the minimum friction coefficient, with an average friction coefficient of 0.14. This paper provides a new approach for microtexture processing of metal materials.

Investigating hailstorm updrafts and nowcasting hail size using a novel radar-based updraft detection

Abstract Nowcasting hail size poses a major challenge in operational practice due to physical limitations of weather radar technology once hailstones are sufficiently large to enter the resonance scattering regime. Numerous radar-based hail size proxies have been derived in recent decades, but their performance is generally poor in identifying giant hail (≥ 10 cm). Using a novel thunderstorm updraft detection method, we examine the updraft characteristics of hailstorms in the U.S. Great Plains based on a NEXRAD dataset of 114 hail events between 2013 and 2023. We find that some radar-derived variables within the detected updraft are well suited for discriminating between small (1.0 - 3.0 cm) and severe (≥ 3.5 cm) hail, e.g. minimum co-polar cross-correlation coefficient in the mid-level updraft, whereas other radar metrics such as the area of reflectivity > 50 dBZ in the upper portion of the updraft suggest the presence of giant hail. However, the statistical distributions of each variable overlap for different hail sizes and there is no single metric which performs well across the entire hail size spectrum. Therefore, we trained a Random Forest model to nowcast hail size categories using a multitude of these radar metrics. The model shows promising performance for discriminating hail sizes > 5 cm but requires further refinement for smaller hail. We showcase the model’s capabilities for a set of hailstorms in the Great Plains.

An ionic liquid crystal functionalized nanocellulose lubricant additives

Cellulose, one of nature's most abundant, clean, and sustainable resources, has often shown unsatisfactory results when used as bio-lubricant additives. Herein, nanocellulose (NC) from amorphous waste natural poplar was extracted using deep eutectic solvent encapsulation treatment and chlorine bleaching process. Subsequently, 1-hexadecyl-3-methylimidazolium bromide was integrated onto NC using a one-step hydrothermal treatment (high-temperature and high-pressure environment) to obtain ionic liquid crystal (ILC) functionalized products (named as ILC-NC). After ball-milling process and solid phase separation step, ILC-NC exhibits excellent dispersion stability and lubrication properties in the liquid phase (including water and vegetable oil). Based on the polar and colloidal activity properties of ILC, it can form an ordered molecular layer on NC surface and form a lubricating film-like structure, making NC smoother and sliding well. Compared to ILC/NC aqueous dispersion, ILC-NC reduces the coefficient of friction and wear rate on steel disk surface by 68.75 % and 74.07 %, respectively. The minimum coefficient of friction was further reduced to 0.032 as dispersing ILC-NC in sunflower oil, showing a reduction of 0.134 (77.91 %) compared to pure sunflower oil. Finally, the lubrication theoretical model calculation reveals the lubrication state of ILC-NC on the steel disk surface and proposes the lubrication mechanism.

Experimental investigation of slit weir discharge

ABSTRACT A rectangular slit weir is used to measure small flows, namely, those flows less than 5 L/s and contraction ratios (b/B) less than 0.25. In the present study, flow tests were conducted in a laboratory setup with various contraction ratios (b/B) under models A (b/B = 1/12), B (b/B = 1/8), C (b/B = 1/6), D (b/B = 5/24), and E (b/B = 1/4). The dimensional analysis revealed that b/B, the height of the flow on the crest of the weir to the height of the weir crest (h/P), the Reynolds number (Re), and the Weber number (We) are effective parameters for predicting the discharge coefficient of the slit weir. The experimental results indicated that the discharge coefficient is variable for different contraction ratios; the maximum average discharge coefficient was achieved at the lowest b/B (Model A), with a value of 0.72. The minimum average discharge coefficient obtained in Model B equals 0.639. In addition, former prediction equations were compared with the obtained experimental data, and the minimum, average, and maximum errors were calculated. Furthermore, a relationship was established for deriving the discharge coefficient in slit weirs with R2 = 0.9212, RMSE = 0.02244, and MAE = 0.0134 based on the obtained experimental data with four effective parameters, b/B, h/P, Re, and We.

Magnetic resonance imaging-based radiomics for predicting infiltration levels of CD68+ tumor-associated macrophages in glioblastomas.

Tumor-associated macrophages (TAMs) are important biomarkers of tumor invasion and prognosis in patients with glioblastoma. We combined the imaging and radiomics features of preoperative MRI to predict CD68+ macrophage infiltration. Clinical, MRI image, and pathology data of 188 patients with glioblastoma were analyzed. Overall, 143 patients were included in the training (n = 101) and validation (n = 42) sets, whereas 45patients were included in an independent test set. The optimal cut-off value (14.8%) was based on the minimum p-value formed by the Kaplan-Meier survival analysis and log-rank tests which divided patients into groups with high CD68+ TAMs(≥ 14.8%) and low CD68+ TAMs (< 14.8%). Regions of interest and radiomics features extraction were based on contrast-enhanced T1-weighted images (CE-T1WI) and T2WI. Multi-parameter stepwise regression was used to create the clinical, radiomics, and combined models, each evaluated using the receiver operating characteristic curve. Decision curve analysis was used to assess the clinical applicability of the nomogram. Aclinical model based on the minimum apparent diffusion coefficient (ADCmin) revealed an area under the curve (AUC) of 0.768, 0.764, and 0.624 for the training set, validation set, and test set, respectively. The 2D radiomics model, based on two features, revealed an AUC of 0.783, 0.724, and 0.789 for the training, validation, and test sets, respectively. The 3D radiomics model, based on three features, revealed AUCs of 0.823, 0.811, and 0.787 for the training, validation, and test sets, respectively. The combined model, with ADCmin and radiomics features, showed the best performance, with AUCs of 0.865, 0.822, and 0.776 for the training, validation, and test sets, respectively. The calibration curve of the combined model nomogram showed good agreement between the estimated and actual probabilities. The combined model constructed using ADCmin, aquantitative imaging parameter, combined with five key radiomics features can be used to evaluate the extent of CD68+ macrophages before surgery.

Controllable phase transition process of polycrystalline diamond surface for low friction via suppressing oxygen involved tribochemical reactions

The diamond inner wall of drawing die is crucial for the precise formation of ultra-fine wires during the drawing process. Unexpectedly, when drawing soft metal wire, a significant wear occurs on hard-phase diamond surface, resulting in increased friction at the drawing interface, which leads to the wire cross-section distortion, uneven wire diameter, surface scratches and burrs. In this study, the interface interaction and friction products between diamond and iron were investigated, focusing on the primary factors influencing diamond phase transitions by adjusting friction atmosphere. Whether in air or nitrogen, the friction coefficient (CoF) decreases with the increase of load, but CoF value is relatively lower in nitrogen environment. The friction curve of diamond against iron stabilized after an initial downward trend, reaching a minimum CoF of 0.08 in nitrogen under a load of 15 N. The friction mechanism is explained through material transfer, friction products, phase transition, tribolayer formation, and interfaces interactions. It is speculated that in nitrogen, even if a small amount of oxide forms on iron surface, iron remains in contact with diamond, generating a large amount of iron carbide and inducing the graphitization of diamond, which would act as a lubricating role. In contrast, in air, oxygen atoms continuously interact with iron, forming a dense oxide film at the friction interface, which prevents carbon from continuous contacting iron atoms and limits the formation of iron carbide. Overall, the discovery provides new insights into the interaction between metals and diamonds, and offers theoretical guidance for the drawing of iron wires.

Demonstration of record sensitivity for water vapor detection by means of comb-locked cavity ring-down spectroscopy

We report on the development, characterization, and test of a comb-locked cavity ring-down spectrometer (CL-CRDS) operating in the spectral region around 1.39 µm. The system is based on the use of a hemispherical optical resonator with a finesse as high as ∼507000, which gives an empty-cavity ring-down time of about 285 µs. An Allan-Werle analysis on repeated acquisitions of the ring-down time at a fixed laser frequency suggests a minimum detectable absorption coefficient of 2×10−12cm−1 for the optimum integration time of 45 s. This limit can be exceeded by adopting the strategy of long-term spectral averaging. Taking advantage of the frequency stability guaranteed by the optical frequency comb, the CL-CRDS spectra were averaged over more than two days, thus removing efficiently the effect of mechanical, acoustic, and thermal noises. As a result, we could achieve a minimum detectable absorption coefficient as low as 3.7×10−13cm−1, which corresponds to a limit of detection for H2O in N2 of nine parts per trillion and a H2O partial pressure of 2×10−8 Pa (or 2×10−10 mbar). The potentialities of our approach are demonstrated by recording the absorption features of HD16O and HD18O in flows of ultra-high-purity N2 and ambient air, respectively.

High repetition-Rate laser diode side-Pumped burst-mode Nd:YAG laser with enhanced output pulse uniformity

A theoretical and experimental investigation is conducted on a high repetition-rate side-pumped burst-mode Nd:YAG laser. The absorbed pumping power distribution and laser resonator are meticulously optimized to enlarge the area of the fundamental mode and improve thermal stability. With the 1 ms pumping duration and a pumping frequency of 10 Hz, the pulsed laser’s burst energy, peak power, and pulse width achieve 0.29 J, 347 kW, and 16 ns, respectively, with the Q-switched repetition rate of 50 kHz. The minimum coefficient of variation for the laser pulse train remains below 5 %. This study represents the first demonstration of a long-term reliable output from a high-energy, nanosecond-pulsed, side-pumped Nd:YAG burst laser operating at 50 kHz.

A biomimetic micro-texture based on shark surface for tool wear reduction and wettability change

Aiming at the problems of severe tool wear and difficulty in ensuring machining surface quality during the cutting process of Ni-base superalloy, a micro-texture design method resembling a shark surface is proposed, which simplifies the skin teeth on the shark surface into a diamond shaped structure with ribs. Different micro-textured samples were prepared using femtosecond laser, and surface wettability characterization and friction and wear experiments were conducted to study the wear reduction and anti wear effects of micro-texture. The parameter combinations with the maximum contact angle and the minimum coefficient of friction were selected. The wear mechanism of YG8 carbide alloy and GH4742, as well as the wear reduction mechanism of microstructure were revealed. Biomimetic cutting tools were prepared and their effectiveness in controlling tool wear, reducing cutting forces, and improving machining quality was verified through milling experiments.

Molybdenum Disulfide (MoS2) Film Formation and Friction Properties of Molybdenum Phosphate Additive in Combined Condition with Zinc Dialkyldithiophosphate (ZnDTP)

This article describes experimental studies on low friction film formation of molybdenum phosphate (MoP) in combination with zinc dialkyldithiophosphate (ZnDTP). The spinning type friction tests were conducted, and in the test procedure, the test using ZnDTP containing oil was conducted following the test using MoP oil. The results showed that after switching to ZnDTP, the friction coefficient steeply decreased and reached approximately 0.06 in 1,353 ppm of sulfur concentration, and minimum friction coefficient depended on the concentration of sulfur in the oil with ZnDTP. Moreover, it is shown that the friction coefficient gradually increased, and that the coefficient at 1 h after switching to ZnDTP corresponded to that in ZnDTP alone. Raman spectroscopy demonstrated that, at 5 min after switching to ZnDTP, the molybdenum disulfide (MoS2) film was formed on the contact surface. Also, energy dispersive x-ray spectroscopy (EDX) analysis results indicated that at 1 h after switching to ZnDTP, the film derived from ZnDTP was composed of phosphorus, oxygen, and sulfur. These results suggest the film formation mechanism of MoS2: molybdenum oxide, such as iron (II) molybdate (FeMoO4), formed in the test of MoP, was then transformed into MoS2 by sulfur or a sulfur containing compound from ZnDTP decomposition.

Portuguese validation of the foot health status Questionnaire in patients with diabetic foot disease

Purpose This study aims to adapt and validate the Foot Health Status Questionnaire, developed by Bennett et al., in Portuguese patients with diabetic foot. Materials and methods A cross-sectional study was conducted with 143 patients with diabetic foot. A principal component analysis with oblique rotation and a confirmatory factor analysis using structural equation modeling were performed. Results The Portuguese version of the FHSQ (FHSQ-PT) in patients with diabetic foot remains equal to the original version, although with all factors correlated with each other. All scales presented high internal consistency values (pain: ω = 0.884; function: ω = 0.890; general foot health: ω = 0.910; and footwear: ω = 0.702), except for the footwear scale, although with a minimum acceptable coefficient. The FHSQ-PT scales showed good convergent validity and good discriminant validity. The FHSQ-PT scales were also able to discriminate between male and female patients as well as between patients with an active diabetic foot ulcer from those who did not. Conclusions The results of the validated FHSQ-PT for Portuguese patients with diabetic foot showed good psychometric properties, being a useful, objective, and small instrument that may be used in clinical practice by health professionals without consuming too much time.