Resistance Parameters Research Articles

Alterations in Biomarkers Associated with Cardiovascular Health and Obesity with Short-Term Lifestyle Changes in Overweight Women: The Role of Exercise and Diet

Background and Objectives: In this study, the effects of an eight-week exercise and nutrition program on blood lipids, glucose, insulin, insulin resistance (HOMA-IR), leptin, ghrelin, irisin, malondialdehyde (MDA), and Growth Differentiation Factor 15 (GDF15) in overweight women were investigated. Materials and Methods: A total of 48 women volunteers participated in this study. The participants were randomly divided into four groups: control (C), exercise (E), nutrition (N), exercise + nutrition (E + N). While no intervention was applied to group C, the other groups participated in the predetermined programs for 8 weeks. At the beginning and end of this study, body composition was measured and blood samples were taken. Results: It was determined that the body composition components, lipid profile indicators, insulin, glucose, insulin resistance, leptin, ghrelin, irisin, and MDA parameters examined in this study showed positive changes in the intervention groups. Group E had a greater effect on body muscle percentage, MDA, and irisin levels, while group N had a greater effect on blood lipids and ghrelin levels. Conclusions: As a result, it is thought that lifestyle changes are important to improve cardiovascular health and combat obesity, and that maintaining a healthy diet together with exercise may be more effective.

DETERMINATION OF THE STABILITY PERIOD OF TURNING CUTTERS FOR HEAVY MACHINE TOOLS

To determine the optimal cutting modes under conditions of increased requirements for the stability of technological processes, it is necessary to take into account the value of the tool life with a given probability. In this paper, the stability dependence for prefabricated cutters used on heavy machine tools with maximum diameters Dmax = 1250-2500 mm is specified using the group argumentation method. The study presents a new mathematical model that establishes the relationship between tool fracture resistance and key operational parameters. This model incorporates the probabilistic nature of tool performance, which allows for a more accurate assessment of the impact of part size variation, cutting conditions, and process variability. The proposed relationship facilitates the determination of cutting modes that not only increase tool stability but also ensure the reliability and efficiency of heavy machine tools in industrial environments. This mathematical dependence makes it possible to take into account the variation of workpiece parameters and cutting modes, which is especially important when working with large-sized parts on heavy-duty machine tools. The results of the study are of practical importance for industry, as they make it possible to increase the sustainability and productivity of technological processes.

Modeling water balance components of conifer species using the Noah-MP model in an eastern Mediterranean ecosystem

Abstract. Few studies have investigated the performance of land surface models for semiarid Mediterranean forests. This study aims to parameterize and test the performance of the Noah-MP land surface model for an eastern Mediterranean ecosystem. To this end, we calibrated the model for root zone soil moisture and transpiration of two conifer species, Pinus brutia, and Cupressus sempervirens, in a plantation forest on the Mediterranean island of Cyprus. The study area has a long-term average annual rainfall of 315 mm. Observations from 4 sap flow and 48 soil moisture sensors, for the period from December 2020 to June 2022, were used for model parameterization. A local sensitivity analysis found that the surface infiltration (REFKDT), hydraulic conductivity (SATDK), and stomatal resistance (RSMIN) parameters had the highest impacts on the water balance components (soil evaporation, tree transpiration, surface runoff, and drainage). The model performed better during the wetter 9-month validation period (379 mm rain) than during the drier 10-month calibration period (175 mm rain). Average soil moisture in the top 60 cm of the soil profile was reasonably well captured for both species (daily Nash–Sutcliffe efficiency > 0.80 for validation). Among the three soil layers, the second layer (20–40 cm) showed better simulation performance during both periods and for both species. The model exhibited limitations with respect to simulating transpiration, particularly during the drier calibration period. The inclusion of a root distribution function in the model, along with the monitoring of soil moisture below the 60 cm soil depth in the field, could improve the accuracy of model simulations in such water-limited ecosystems.

Summary of the results of field and laboratory studies of hydraulic resistance during channel bending

The reliability of channel forecasts, performed using mathematical modeling methods in the design of engineering activities on shipping rivers, largely depends on the accuracy of the assessment of hydraulic resistance and sediment transport parameters. Therefore, the hydraulic resistance of natural channels is one of the largest problems in the dynamics of channel flows and is the object of close attention of scientists. In the resistance of natural channels, roughness appears in three forms: the first of them is the roughness of the granular surface of the bottom; the second is the roughness created by boulders and the third type is the roughness of microforms: ripples and ridges. Channel mesoforms also contribute to the resistance to water movement: spits, side streams, middle streams, islands, bends of the channel and such complex formations as riffles. This type of resistance is usually called the resistance of the channel form. The resistance of the natural channel shape due to the movement and deformation of mesoforms can change significantly over time. The complexity and insufficient study of this issue significantly limit the possibilities of a theoretical approach to its solution. Therefore, the obtained results are mainly empirical or semiempirical in nature. The paper presents the results of experimental and field studies that allowed us to identify the main features of flow movement in winding sections of rivers. One of the features of flow movement at channel turns is the possibility of additional energy losses. The total resistance of a curved section of a channel is made up of three main parts: the resistance of the granular surface of the bottom, the resistance of the bottom ridges, and the resistance of the channel shape. The additional resistance created by the bend depends on the curvature of the channel, the rate of change in depth along the length of the bend, and also reflects the impact of side streams formed near the convex bank on the flow.

ИССЛЕДОВАНИЕ СВОЙСТВ РЕЗИН НА ОСНОВЕ СКЭПТ, НАПОЛНЕННЫХ ПОЛИАКРИЛОНИТРИЛОМ

The article studies rubber mixtures based on EPDM with polyacrylonitrile (PAN), including those previously subjected to partial pyrolysis. Pyrolysis, oil resistance, coke number and physico-mechanical parameters of the studied rubbers were studied. It is shown that the introduction of PAN makes it possible to improve the resistance of rubbers to high-temperature heating and the oil resistance of vulcanizates.

Wellbore Stability Analysis Based on the Combination of Geomechanical and Petrophysical Studies

Determining the physical and mechanical properties of rocks is crucial for planning drilling operations. Ignoring geomechanical studies and tools has led to millions of dollars in additional costs related to drilling, meshwork optimization, production optimization, casing collapse, and other issues. These costs can be managed with a thorough geomechanical study. Additionally, some costs may not be apparent in the short term but will become significant over the life of the field. Long-term reservoir management is essential to control these costs. Issues such as reservoir compression, rock cover fractures, and gas storage, if neglected in the short term, can lead to substantial and irreparable damage to the reservoir over time. The "geomechanical model" is fundamental to geomechanical studies, particularly regarding wellbore stability. Given the importance of reservoir geomechanics and petrophysics, this research investigates wellbore stability analysis by combining geomechanical and petrophysical studies through the construction of a one-dimensional geomechanical model of the well. First, the dynamic geomechanical coefficients of the rock for the studied depth range were calculated from wells and petrophysical charts. Then, the static geomechanical coefficients of the rock were estimated based on laboratory-developed relationships. Subsequently, rock mechanics test results were used to estimate rock resistance parameters. The pore pressure was estimated using the compressibility and Eaton methods for the studied range from Well No. 5. Comparing the results of these two methods with RFT test data indicated that the compressibility method is more accurate than Eaton’s method. By estimating the in situ and induced stresses in the well's studied area, the lower and upper limits of the safe mud weight were calculated using the Mohr-Coulomb and Hooke-Brown criteria. Comparison of the results showed that the Mohr-Coulomb criterion is more accurate and, moreover, more conservative than the Hooke-Brown method.

Effect of feed rate during induction hardening on the hardening depth, microstructure, and wear properties of tool-grade steel work roll

Rolls are the most critical yet vulnerable parts of cold rolling mills. It is crucial for them to withstand long rolling campaigns without losing surface roughness or incurring damage. Newly developed rolls are made from tool-grade steel with high roughness, lower wear, and high damage resistance. One of the most important advantages is the elimination of the need for chrome plating, which is currently widely used on standard steel rolls but is ecologically harmful. We investigated a type of steel with 8% chromium for use in cold rolling using light optical microscopy (LOM), X-ray crystallography (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), hardness measurements, and tribological tests. In this study, a roll with a diameter of 325 mm was electro-slag remelted and forged, machined to a diameter of 305 mm, and quenched and tempered to simulate industrial roll production. A forged roll was induction heated and hardened at four different feed rates (i.e., 24 mm/min, 30 mm/min, 36 mm/min, and 42 mm/min), tempered at 515℃ for 24h and again at 480℃ for 24h, and dissected for in-depth analysis. We identified a clear relationship between the feed rate of the roll during induction hardening and the depth of hardness, the sizes of carbides, and the wear properties of the roll. By reducing the feed rate of the roll through the inductor, we increased the depth of the hardened layer from 16 mm (at a feed rate of 36 mm/min) to 25 mm (at a feed rate of 24 mm/min), which is a 56.25% increase. Such an increase is expected to extend the lifespan of the working roll without having negative effects on the wear resistance and other important parameters. XRD analysis showed that the sample had a 0.4% residual austenite, which means it had a significantly lower risk of roll damage during operation than standard steel grades

Evaluation of the Biological Properties of the Bacteriodaceae Family Using the Caco-2 Cell Line.

Disorders in the composition of the microbiota are often associated with pathological processes in the body. The use of new biotherapeutic drugs containing bacteria from normal microflora to correct these disorders may contribute to more effective treatment. The Bacteroidaceae family dominating in microflora is a candidate for inclusion in bacterial preparations. The adhesion properties of five bacterial strains from the Bacteroidaceae family were analyzed using the Caco-2 cell line and their effect on the transepithelial electrical resistance parameters (TEER) was assessed to determine the extent of their impact on the cell monolayer integrity. This approach allowed the selection of strain B. intestinalis 181, which was characterized by a moderate adhesion activity combined with a relatively low effect on the TEER parameter.

Исследование проницаемости эпителиального слоя клеток TEER методом

The study investigated the electrical characteristics of the Caco-2 cellular layer grown on a cellulose acetate membrane using impedance spectroscopy and cyclic voltammetry methods. The effect of ethanol solutions of varying concentrations on the electrophysical properties of the cellular layer was studied. During measurements of the layer characteristics by the cyclic voltammetry method under direct current, it was found that its resistance before ethanol treatment was 642 kOhm. Treatment with a 25% ethanol solution increased this value to 645 kOhm, while 50% and 95% solutions decreased it to 505 kOhm and 373 kOhm, respectively. During the study of the cellular layer's properties using impedance spectroscopy with alternating current, dependencies of the real and imaginary parts of the resistance on the ethanol concentration in the treatment solution were obtained. The obtained data were used to construct Nyquist diagrams. Their analysis allowed for the proposal of an equivalent circuit describing the process of current flow through the studied system. The equivalent circuit included parameters of paracellular transport, membrane resistance and capacitance, as well as elements accounting for electrode polarization. As a result, values of capacitance and membrane layer resistance were obtained. It was established that the membrane layer capacitance changes under the influence of ethanol. When treated with a 50% ethanol solution, capacitance increases, indicating degradation of the cell membrane and a reduction in its barrier function. Treatment with a 95% solution led to a decrease in capacitance, which can be attributed to the compression of the cell layer, reducing the capacitance contribution to the system's overall conductivity. The results demonstrate the importance of quantitative analysis of cellular electrical parameters for studying their response to chemical stress and confirm the potential of such approaches in biomedicine for creating sensors and «organ-on-a-chip» systems.

Impact of Serum Platelet Count on Infertility in Polycystic Ovary Syndrome: A Retrospective Case-Control Study

Background: This study intended to investigate the correlation between insulin resistance (IR) and coagulation parameters in women with polycystic ovary syndrome (PCOS) and their effects on infertility. Methods: We retrospectively included 380 PCOS patients and 143 healthy controls between January 2018 and January 2021. Clinical data, including age; body mass index; white blood cell (WBC), neutrophil (NE), lymphocyte (Lym), and platelet (PLT) counts; and D-dimer, plasma sex hormone, fasting blood sugar, and fasting insulin levels, were collected. The relationship between these markers and PCOS was assessed. Results: Elevated homeostatic model assessment of insulin resistance score was independently related to infertility in women with PCOS (odds ratio [OR] = 1.825, 95% confidence interval [CI]: 1.091–3.055, p = 0.022). WBC (7.29 [5.99–8.59] vs. 6.25 [5.33–7.40], p < 0.001), NE (3.91 [3.22–4.98] vs. 3.36 [2.62–4.51], p = 0.001), PLT (276 [244.5–317.5] vs. 251.5 [219.25–281.5], p < 0.001), and Lym (2.51 [2.02–3.11] vs. 2.08 [1.85–2.53], p < 0.001) counts, and D-dimer levels (0.22 [0.15–0.42] vs. 0.20 [0.12–0.31], p = 0.023) in the serum were markedly higher in PCOS patients with IR. Furthermore, multivariate logistic regression analysis revealed that increased serum PLT count (OR = 3.066, 95% CI: 1.052–8.939, p = 0.040) and BMI (OR = 5.06, 95% CI: 1.166–21.963, p = 0.030) were independently correlated with the risk of IR in PCOS patients. Moreover, increased PLT count was independently related to infertility (OR = 3.380, 95% CI: 1.272‒8.982, p = 0.015). Conclusions: Elevated PLT count serve as an independent responsible role for infertility in PCOS women with IR, which indicate that PLT count might be a potential predictive marker for infertility in PCOS women with IR.

Molecular dynamics simulation of arc ablation on Mo or W doped CuCr contact materials

To improve the ablation resistance of the contact material in vacuum circuit breakers (VCBs), molecular dynamics (MD) was used to simulate the microscopic arc ablation process. Reinforced CuCr alloys doped with elements Mo or W were designed using ablative mass as the characteristic parameter for ablation resistance. The results demonstrate that Mo or W doping can improve the ablation resistance of the alloys to some extent, and the doped alloys have better ablation resistance than CuCr50. Moreover, Mo or W-doped CuCr alloys with an original Cu content of 70–80 at%, which have less ablative mass than CuCr50, are most suitable for improving the contacts’ ablation resistance.

Effectiveness of Probiotics, Prebiotics, and Synbiotics in Managing Insulin Resistance and Hormonal Imbalance in Women with Polycystic Ovary Syndrome (PCOS): A Systematic Review of Randomized Clinical Trials.

Background/Objectives: Polycystic ovary syndrome is a common endocrine disorder in women of reproductive age characterized by insulin resistance and hormonal imbalances. Recent research suggests that probiotics and synbiotics may improve these parameters by modulating the gut microbiota. This study systematically reviewed randomized clinical trials evaluating the impact of probiotic, prebiotic, and synbiotic supplementation on insulin resistance and hormonal parameters in women with PCOS. Methods: Exhaustive searches were conducted in PubMed, Cochrane CENTRAL, Scopus, Web of Science, and Embase, following PRISMA guidelines. Randomized trials assessing supplementation with probiotics, prebiotics, or synbiotics for at least 8 weeks in women diagnosed with PCOS according to the Rotterdam criteria were included. Data on participants, interventions, and outcomes related to insulin resistance and hormones were extracted. Results: Eleven studies from Iran involving overweight or obese women aged 15 to 48 were included. Probiotic and synbiotic supplementation showed significant improvements in insulin resistance (reductions in HOMA-IR, fasting glucose, and insulin), lipid profiles (decreased LDL and triglycerides; increased HDL), and hormonal balance (increased SHBG, decreased total testosterone). Synbiotics had more pronounced effects than probiotics or prebiotics alone. Adherence was high, and side effects were minimal. Conclusions: Despite promising results, limitations such as small sample sizes, homogeneous populations, and short intervention durations limit the generalization of the findings. Larger, longer, multicenter trials with diverse populations and standardized methodologies are needed to confirm the efficacy and safety of synbiotics in managing PCOS. Integrating these interventions could improve clinical management and quality of life for affected women, but additional evidence is required to support widespread use.

Application of gray relational analysis for optimizing stud welding parameters of IF 7114 steel for the automotive industry

In this study, the application of stud welding to IF 7114 steel sheets in the automotive industry using stainless steel and copper-plated steel studs with different diameters and welding voltages was investigated. The aim is to optimize welding parameters and investigate their effects on the mechanical properties of the weld zone. Taguchi optimization and gray relational analysis were used to identify the best welding parameters for tensile strength and torque resistance. Results showed that the highest tensile strength and torque resistance were achieved with a stainless steel M8 stud diameter and 150 V welding voltage, while the lowest values were observed with copper-plated steel M5 studs and 180 V voltage. Additionally, stainless steel studs consistently outperformed copper-plated steel in both tensile strength and torque resistance. The study concludes that stainless steel studs, particularly with an M8 diameter at 180 V, offer the most favorable welding performance.

Effects of exercise and dietary interventions on asprosin, leptin, and lipid metabolism in males with abdominal obesity, a randomized controlled trial

Addressing abdominal obesity requires multifaceted strategies, with physical activity and diet playing a pivotal role. The objective of this study was to assess alterations in body composition, adipokine concentrations, insulin resistance parameters, and lipid metabolism in males with abdominal obesity following two distinct interventions: exercise alone and exercise combined with a specific diet. The study involved 44 males with abdominal obesity (average age 34.7 ± 5.5 years, waist circumference [WC] 110.3 ± 8.5), randomly assigned to three groups: an experimental group with aerobic-resistance exercise (EG, n = 16), an experimental group with aerobic-resistance exercise combined with a high-protein, low-glycemic index carbohydrate diet (EDG, n = 16), both interventions lasting 6 weeks, and a control group without interventions (CG, n = 12). Body composition (body mass [BM], body fat percentage [BF%], fat-free mass [FFM], android body fat percentage [ANDR]), as well as biochemical blood analyses (asprosin [ASP], leptin [LEP], quantitative insulin sensitivity check index [QUICKI], and total cholesterol [TC]), were conducted at baseline and after 6 weeks of intervention. The impact of interventions on the analyzed variables among groups was assessed using mixed ANOVA tests with post-hoc comparisons. Effect size (ES) was also evaluated using \U0001d702p2. Significant reductions in ASP concentration after intervention were observed in both EG (p = 0.04) and EDG (p = 0.01). However, post-hoc tests revealed a decrease in LEP only in the EDG group (p < 0.01). In EDG substantial decreases after 6 weeks of intervention were noted in BM (p < 0.01), BF% (p < 0.01), ANDR (p < 0.01) and TC (p < 0.01). The most notable increase in FFM was observed in the EDG group (p < 0.01). More favourable metabolic outcomes were confirmed in the group combining diet with exercise, where there was a notable reduction in ASP levels by 16% and LEP by 48% after 6 weeks of intervention, compared to the group undergoing exercise alone.

Triglyceride-glucose index predicts postoperative overall survival in hepatocellular carcinoma: a retrospective cohort study

BackgroundInsulin resistance is important in hepatocellular carcinoma (HCC) carcinogenesis and progression. The triglyceride-glucose (TyG) index, triglyceride to high-density lipoprotein cholesterol (TG/HDL-c) ratio or TyG-body mass index (TyG-BMI) are three non-invasive parameters for insulin resistance. However, their prognostic role in HCC patients undergoing hepatectomy remains unclear.Materials and methodsHCC patients who underwent hepatectomy at the Meizhou People’s Hospital from May 2011 to February 2023 were retrospectively explored. Patients were classified into high and low groups based on different TyG, TG/HDL-c, and TyG-BMI indices. The prognostic role of TyG, TG/HDL-c, and TyG-BMI was evaluated using Kaplan–Meier analysis and Cox regression models. A nomogram incorporating significant prognostic factors was constructed and validated.ResultsA lower TyG, lower TG/HDL-c, and lower TyG-BMI were linked to worse overall survival (OS) in HCC patients. Multivariate analysis indicated the TyG index, but not the TG/HDL-c and TyG-BMI index, could independently predict HCC OS. The nomogram incorporating the TNM stage and TyG index demonstrated good calibration, discriminative ability, and clinical benefit for predicting OS in HCC patients.ConclusionsThe TyG index could independently predict HCC OS after hepatectomy in this cohort. The nomogram incorporating the TyG index may aid in the prognosis management of HCC.

A Correlation Relating the Residual Strength Parameters to the Proportions of Clay Fractions and Plasticity Characteristics of Overburden Sediments from the Open-Pit Mine Drmno

One of the prerequisites for the safe exploitation of surface mines is the stability of the working and final slopes of the mine. In order to ensure this, it is necessary to carry out detailed field and laboratory geomechanical tests of the soil and, based on the obtained results, make calculations related to stability analyses. The results obtained in this way are used for dimensioning the slope of exploitation slopes (excavation). Landslides occur when the ultimate shear strength is reached, and therefore, the adequate definition of shear strength parameters is one of the essential prerequisites for successfully solving the stability problem. Unlike earlier tests in Serbia, when the residual shear strength parameters were determined based on the usual conventional methods (direct shear apparatus, triaxial apparatus), this time, in addition to the direct shear apparatus, a ring shear apparatus was also chosen for testing. The paper shows the method of determining the residual shear strength parameters of high plasticity gray clays and siltstones of roof sediments from open pit mine Drmno, using direct and ring shear apparatus. The results show that the residual angle of internal friction for gray clays obtained with the ring shear apparatus is 9.9–10.8°, and for the siltstone, it is 11.8–12.9°, both of which are lower than the values obtained with the direct shear apparatus. In addition, correlations between the residual parameters of soil shear resistance and some physical indicators (plasticity index, clay content) are provided, showing high correlation coefficients. The proposed correlations should be used only when time and financial constraints prevent the execution of actual tests to determine residual shear strength, as concrete experimental procedures provide a much more reliable assessment of the residual strength properties of the soil.

Analysis of the Optimum Performance for Polymer and Polymer-Nanocomposite-modified Asphalt by Using Multicriteria Decision Analysis.

The influence of Acrylate Styrene Acrylonitrile (ASA) and ASA/nanosilica (ASA/Si) additives was investigated by using a dynamic shear rheometer (DSR). Firstly, an ASA polymer was blended with the virgin asphalt binder at two different concentrations (3% ASA and 5% ASA). After observing that 5% ASA was the optimum concentration for modification, nanosilica particles were further incorporated into the 5% ASA-modified asphalt binder with two different percentages (5% ASA 3%Si; 5% ASA 5%Si). Frequency sweep tests were conducted across various frequencies at elevated temperatures. The experimental outcomes were analyzed using master curves, rutting, and fatigue resistance parameter plots. Additionally, to provide a more holistic analysis, two different multicriteria decision analysis (MCDA) techniques, namely the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) and the Technique for the Order of Preference by a Similarity to Ideal Solution (TOPSIS), were conducted to identify the best-performing asphalt binder by considering three different parameters: workability, performance under different conditions, and cost. The frequency sweep tests showed that the 5% ASA 5%Si asphalt worked best in terms of resistance to rutting. On the other hand, the virgin binder performed better than all modified binders when it failed to resist fatigue. On the other hand, the PROMETHEE analysis identified the 5% ASA-modified asphalt binder as the optimal choice, while the TOPSIS analysis determined that the 5% ASA 3%Si-modified binder provided the best performance. The differences between the experimental results and the MCDA were due to using more than one evaluation parameter and looking at how well the asphalt binder worked at different temperature ranges at the same time.

Assessment of Insulin Resistance, HOMA-IR, and QUICKI Levels in Patients with Endometrial Cancer and Hyperplasia

Aim: To analyze insulin resistance and related parameters in patients with endometrial cancer and hyperplasia. Methods: The study included 102 patients in 3 groups. Group I and II included patients with a histologic diagnosis of endometrial cancer (n=41, 40.2%) and endometrial hyperplasia (n=31, 30.4%) based on the final pathology report. Group III was the control group and included patients who had undergone surgery for a benign indication other than endometrial hyperplasia (n=30, 29.4%). Age, body mass index (BMI), menarcheal age, menopausal status, gravidity, parity score, diabetes, oral contraceptive status, fasting glucose levels, insulin levels, endometrial thickness, HOMA-IR and QUICKI scores were assessed. Results: The mean age of group I was statistically higher than that of group II (55.3±9.5 vs. 48.8±7.1, p=0.002). The average BMI of the two groups was similar (p=0.076). When fasting glucose values were evaluated, group I showed significantly higher values compared to group II. The mean insulin and HOMA-IR values in the control group were significantly higher than those in group I (p

Numerical model of curved composite tiles under low-velocity impact loading

In recent years, composite structures have seen widespread application across diverse industries, including automotive and aerospace, owing to their favourable strength-to-weight ratio. However, these structures, particularly high-pressure vessels, are susceptible to extreme loadings such as impact forces, resulting in visible and latent damage, ultimately leading to catastrophic failures. Hence, it is imperative to assess such damages diligently. Given the cost implications associated with experimental investigations, numerical methodologies emerge as a potent means for conducting relevant analyses. This paper will introduce a numerical model approach to conducting virtual tests to assess curved carbon fibre composite tiles subjected to low-velocity impact. The primary focus of this study is to consider the impact-induced delamination on composite tiles through a numerical model. The composite tiles are conducted to 90J impact loading. Specifically, the study evaluates filament winding structures’ interface properties (shear resistance) variability during manufacturing. Notably, the parameter of shear resistance significantly impacts the anticipation of intralaminar damage (delamination) after impact loading. Three-point bending tests were performed to calibrate the composite material’s shear interface properties, followed by low-velocity impact tests on the curved composite tiles. The findings indicate that the shear resistance values, which ranged from 14.25 MPa to 60 MPa, play a critical role in predicting delamination, with lower shear resistance leading to increased damage areas. The results underscore the importance of accurately calibrating interface properties to enhance the predictive accuracy of numerical models for curved composite structures under impact loading.

Development of a material selection decision support system for an automotive application

This study presents the development of a material selection decision support system for an automotive rooftop tent. The system uses five parameters of material cost, formability, corrosion resistance, tensile strength and hardness to optimize material choice from a list of aluminium alloy options. This was done before production via the deep drawing process can commence. The parameters were quantified using the average market prices for each alloy, product requirements obtained from the case study and the performance data that was obtained from the uniaxial tensile and hardness tests. These inputs were combined with the developed material selection framework and then programmed into a web-based decision support system for automated, data-driven material selection. The output presents the recommendation for the optimum material that balances cost-effectiveness and performance. The decision support system was successfully used to select the optimum alloy for the rooftop tent. Results show that AA1050 is the optimum material, providing weight reduction at the minimum achievable cost without compromising the product requirements for the rooftop tent. The decision support system is also scalable, and this allows it to be used with larger datasets for different products and processes in the future.