Tear Load Research Articles

Tearing behaviors of coated fabric inflatable tube

In this paper, the tearing properties of the inflatable tube with coated fabrics were investigated. Firstly, uniaxial tensile, shear, and single-edge notched tests were conducted to obtain the material properties. Then, considering the modified stress field model and bulge effect, a theoretical calculation formula for the critical tearing pressure was proposed. Next, based on finite element method, the macroscopic orthotropic elastic continuum models of the single-edge notched test and pressurized cylinder test were established. In numerical model, when the average stress in the critical distance at the crack tip reached the tensile strength, the tearing began. Then, the critical distance was determined when the critical tearing load of the numerical model was closest to the single-edge notched tests’ result. Based on the numerical simulation of pressurized cylinder test, the critical tearing pressure of inflatable tube was obtained. Finally, the pressurized cylinder test and puncturing test were designed and conducted. In the pressurized cylinder test, when the first yarn at the crack tip broke, the critical tearing pressure and configuration around the crack were obtained. Moreover, the correctness of the critical tearing pressure in theoretical calculation formula and numerical model was verified through pressurized cylinder test. In puncturing test of inflatable tube, there were obvious crack expansion and explosion. Based on the theoretical calculation formula for the critical tearing pressure, the predicted results were consistent with puncturing test's results.

Integrated circular economic approach of solid waste management and resource recovery: Poultry feather-based keratin extraction and its application in leather processing

The tanning industry faces considerable environmental challenges due to effluent load and hazardous chemical generation during processes like tanning and retanning. Therefore, this research work addresses these issues focusing on the pilot scale extraction and application of poultry feather-based keratin hydrolysate (KH) in leather manufacturing. Through pilot-scale experiments, optimal parameters for NaOH concentration, reaction temperature, and time were used to extract KH effectively. The study explored KH's potential application in chrome tanning and retanning stages as a chrome exhaust aid and keratin filler, respectively. During basification, KH was introduced to enhance chromium uptake by creating additional sites through the provision of crosslinking with collagen (modifying collagen) for better interaction and formation of complex with chromium, which not only streamlined the process by reducing the need for additional chemicals but also improved the thermal stability of the resulting leather product and enhance, the quality of leather. The shrinkage temperature of experimental wet blue leather was recorded to be above 107oC compared to the control wet blue leather which start to shrink at 104oc. Similarly, the percentage chromic oxide content of the experimental wet blue leather was observed to be significantly higher (3.89±0.20%) than that of the control wet blue leather (2.59±0.15). Furthermore, KH replaced commercial protein fillers during retanning, resulting in leathers with enhanced mechanical strength and organoleptic properties. The experimental crust leather treated with keratin solution at pH (5.5) was determined to have better tensile strength (23.4 N/mm2) and tear load (38.7 N/mm) than the control leather with tensile strength and tear load of 19.4 N/mm2 and 29.1 N/mm, respectively. Analytical techniques such as FTIR and XRD confirmed the presence of essential functional groups and protein structures in the KH solution, respectively. Leathers treated with 100 % KH substitution at pH value of 5.5 exhibited superior properties, including increased mechanical strength and thermal stability. Environmental impact assessments revealed a significant reduction in total dissolved solids in the spent liquor when KH replaced conventional fillers. Overall, this research demonstrates the potential of poultry feather-based keratin as an efficient, environmentally friendly filler in leather manufacturing, offering promising results in improving product quality and reducing environmental pollution.

PHYSICAL-MECHANICAL PERFORMANCES OF STEERING WHEEL COVER LEATHERS IN SPECIAL CONDITIONS

The steering wheel is among the important components of a vehicle, through it having full control over its direction. It is made of a metal base covered with a polymeric material. To improve the look and feel of a steering wheel, usually it is covered by leather. Choosing the material for covering the steering wheel must be done responsibly, because depending on the material, it can generate a certain type of comfort when using the steering wheel. Thus, the current work aims to evaluate the durability and wear resistance of different types of leather coatings used in automotive steering wheels. A series of tests were performed on leather samples before and after exposing them to special conditions (high\low temperature, humidity, UV) like tensile strength and elongation, tear strength, tear load, surface softness, color fastness and flex resistance. All the tests were performed according to actual standards in ICPI accredited laboratory. The results of the experiment showed that the durability and wear resistance of the leather varied significantly depending on the type of coating. Overall, the study provides valuable insights into the characteristics of different types of leather and can help future research involved in developing more durable and long-lasting steering wheel cover leathers.

Effect of crossing warp architecture on tear strength of 3D orthogonal woven T-shaped reinforcements

T-shaped textile composites reinforced by two-dimensional laminates and simple forms of three-dimensional reinforcements are susceptible to tear failure and delamination at the junction. To address these issues and enhance the tear resistance of composite T-joints, 10 types of crossing warp architecture based on three-dimensional woven orthogonal structures were designed, manufactured and characterized with the aim of optimizing the reinforcement architecture. The assessment of the in-plane mechanical behavior was carried out by a tensile tear load applied to the two flanges of the T-shaped reinforcements. The employment of crossing warp architecture effectively enhanced stiffness, tensile strength, and failure strain. Resistance to the failure of the reinforcement was increased as more crossing warp yarns were employed. To further optimize the crossing warp architecture for reinforcement development, the internal and external crossing arrangements were compared. The new finding was regardless of the crossing warp proportions, the external crossing warp led to a higher resistance to the tear force for the reinforcement than the internal crossing warp. The stiffness and tensile strength of the external crossing warp reinforcements exhibited notable improvement, with a maximum increase of 49.1% and 31.1% respectively, compared with that of the internal warp crossing counterparts. The findings in this research will be useful in manufacturing composite T-joints to tailor the reinforcement architecture with different crossing proportions and arrangements for meeting the required mechanical properties.

BAZI MEKANIKSEL DERI VE TEKSTIL STANDART METOTLARININ UYGULAMALI OLARAK KARŞILAŞTIRILMASI

Fabrics, leathers and artificial materials show structurally different properties. For example, if a fabric material is woven, it is formed by connecting the threads at a right angle to each other with a certain system; on the other hand, leather is formed by naturally binding complex collagen fibers with specific and different angles depending on their area. Also, artificial materials are produced disparately using PVC and PU. These structural differences directly affect the mechanical properties of materials and therefore Turkish Standards Institute (TSE) offers different test methods for textile and leather materials. There are some differences between these standards according to the shape/size of test samples, jaw length, speed, etc. Since leather is an expensive material and has a limited area, sample sizes of leather standards are smaller than the dimensions specified in the textile standard; however, sample sizes in textile standards can be a problem for some expensive textile materials e.g., silk, silver-added fabrics, vicuna, etc. The aim of this study is to examine the differences between the results obtained from the textile and leather standard methods. In this scope, the tensile strength, elongation and tear load values of the two different tanned garment leathers, artificial material, and two different kinds of woven fabrics were obtained by applying both leather and textile standard methods. While there was a statistical difference between the two methods in tensile strength and elongation values for all materials, no difference was observed in tear load values.

INFLUENCES OF ALKALI PRETREATMENT ON LYOCELL WOVEN FABRIC PROPERTIES AFTER ABRASION

In this study, alkali pretreatment in various concentrations were applied to Lyocell woven fabrics to decrease the fibrillation tendency of fibers and the influences of alkali pretreatment on tensile and tearing properties of Lyocell fabrics after abrasion were investigated. Alkali pretreatment reduced fibrillation of Lyocell fibers. However, fabric shrinkage occurred because of the increased volume and damaged twisted structure of yarns due to the lateral fiber swelling. The warp/weft densities and crimp ratios increased as the alkali concentrations increased. The breaking and tearing loads of untreated Lyocell fabrics were higher than those of alkali pretreated fabrics since the strength loss caused by alkali pretreatment. The abrasive load caused fiber breakages and fiber entanglements on fabrics and decreased the both breaking and tearing loads. The weave types with long floating interlacements on the fabric surface were more severely damaged by exposing to abrasive load and resulted as higher strength reduction.

Study on tearing strength of woven sisal fabrics for tents and polymer composite applications

ABSTRACT The use of plant fibers as a reinforcement in composites has increased daily owing to their favorable environmental considerations. Fabric properties play a significant role in alignment during composites processing, enhancing the composite properties. However, the fabric structures are formed by warp and weft yarns. These yarns are subjected to axial and shear loads, respectively. However, very limited work has been carried out on the study involving the tearing strength of the fabric. So it is necessary to study the effect of the tearing load of fabrics before converting them into composites. This paper focuses on the tearing strength of the sisal woven fabrics in both warp and weft directions. Two plain and one weftrib fabrics are prepared using sisal fibers, and their physical properties were characterized as per textile testing standards. Tear strength has been determined by Elmendorf Tear and Single Rip Tear Method by varying crosshead speeds. The result shows that woven patterns and number yarns significantly impact tearing strength. In the case of the weft rib pattern, the warp direction exhibits the highest tearing strength compared to the weft direction. Also, in the case of weftrib fabrics, the weft direction indicates better-tearing strength than another woven pattern.

Tearing behaviors of coated fabric membrane structures

To prevent the failure of membrane structures due to excessive loads, the tearing properties of such structures with coated fabrics were investigated in this study. First, the material properties were obtained by conducting tensile, shear, and single-edge notched tests. Thereafter, a structure tearing test was designed and conducted. Test models with different cracks exhibited similar load–displacement of actuator curves, and the critical tearing loads decreased with increasing in crack sizes. However, the decreasing trend gradually declined. Different test models exhibited similar crack expansion processes before the initiation of tearing. After tearing initiated, the crack extension speed and failure mode varied. Based on the displacement results around the crack, the influence of the crack was local before tearing initiated. However, the crack size can determine the timing and mode of the failure of membrane structures. Furthermore, by comparing the tearing test results at the structure and material levels, the crack size and critical tearing strength per unit length were verified as critical parameters for determining a relatively complete tearing mechanism. Finally, due to the differences between the structure tearing and single-edge notched tests, a stress analysis was conducted to confirm the detailed margins/limitations based on a numerical simulation. The critical tearing strength at the crack section was obtained, and the theoretical critical tearing loads were obtained based on the modified stress field model. The results related to the single-edge notched test were smaller, and can therefore provide a relatively safe estimation with respect to the membrane structure tearing test. This study was preliminary, and can serve as a basis for investigating the tearing of membrane structures.

Substitution Experiment of Biodegradable Paper Mulching Film and White Plastic Mulching Film in Hexi Oasis Irrigation Area

Biodegradable paper mulch has the advantages of being easily degradable and environmentally benign, but its own performance and adaptability to harsh environments have not been tested. This paper uses scanning electron microscopy and three-dimensional morphometry to microscopically characterize biodegradable paper mulch and white plastic mulch. To analyze and compare their mechanical and hydrophobic properties, and weather resistance, the two mulches were measured through tensile tear load and static contact angle. A comparative analysis of the effect of mulching in the dry crop area of the Hexi Corridor was conducted by comparing the growth index, farm water heat, soil oxygen content, and yield using maize and flax. The test results show that biodegradable paper mulch films were slightly inferior to traditional white mulch films in terms of mechanical and hydrophobic properties, with inadequate insulation and moisture retention, but better in terms of aging resistance, soil oxygen content, and crop insulation and water storage capacity in the middle and growth stages. White mulch film had a better yield enhancement effect on maize, while with biodegradable paper mulch film, this was more significant with flax.

PROBLEMATIC ISSUES REGARDING THE DEVELOPMENT OF FLIGHT TECHNIQUES FOR AVIATION OF THE ARMED FORCES OF UKRAINE

The purpose of the study is to determine and substantiate the normative values of the strength of the fabric used for the manufacture of LTO, taking into account the results of LTO control tests for aircraft of the Air Force of the Armed Forces of Ukraine conducted by specialists of the test team equipment in the period from 01.06.2020 to 01.09.2021, and mandatory requirements for its strength, defined by the general technical requirements for livelihoods and rescue of aircraft crews.
 During the research was carried out:
 
 study and analysis of regulatory and technical documentation regarding the physical and mechanical properties of materials from which military clothing is made for servicemen;
 analysis of the degree of influence of fabric properties on the quality of LTO products;
 study of the parameters of strength of fabrics from which military clothing for servicemen is made;
 the conditions of application of LTO products were
 
 An analysis of recent publications has revealed that neither in Ukraine nor abroad there is a consolidated normative document or standard on the requirements for the strength parameters of materials used for the manufacture of LTOs. In addition, Ukraine has abolished certain standards (on the quality of fabrics for the manufacture of garments for servicemen) of the former USSR, adopted before 1992 (in accordance with Ukraine's obligations under paragraph 8 of Article 56 of Chapter 3 of the Association Agreement), and on them replacement European standards are not implemented or developed.
 Given the above, there is a need to determine the quality of materials for the manufacture of LTO.
 To determine the adequacy of the indicators obtained in laboratory tests of fabrics from which prototypes of LTO are made, the specialists of State Research Institute for Testing and Certification of Weapons and Military Equipment proposed a new approach, namely, – comparing their values with the values of fabrics from which flight uniforms were made in Soviet times. The strength parameters (maximum tensile force, tear load, etc.) of fabrics from which LTO prototypes are made must not be worse than the strength parameters of fabrics from which domestic LTO samples made by the USSR Armed Forces are made.

Research on the Production of Parchment from Turkey Skin and its Decorative Use

In this study, parchment was made of waste turkey skin and some tests were done. These tests were: Determination of thickness (TS 4117 EN ISO 2589), Determination of tensile strength and elongation (TS EN ISO 3376), Determination of tear load - Part 2: (Double edge tear) (TS 4118-2 EN ISO 3377-2), Leather - of distension and strength of grain (TS 4137 EN ISO 3379), Color fastness to water spotting (TS EN ISO 15700). Due to the low strength properties of turkey skin, a different usage area was tried to be created by making a decorative flower design. In this research, it has been tried to show how a waste material can be transformed into a product with a very high added value.

SARS-COV-2 viral load in tears of patients with COVID-19 in the early symptomatic stages: comparison of two different tear sampling methods.

PurposeTo evaluate the presence of SARS-CoV-2 virus in tears of patients with COVID-19 in the early symptomatic stages and to compare two different sampling methods.Materials and methodIn this cross-sectional study, tears sampling was performed in COVID-19 patients admitted within the first 7 days of symptom onset. The samples were collected with both conjunctival swabs and Schirmer strips. Each specimen was analyzed via RT-PCR. The viral load was evaluated in terms of the cycle threshold value. Ocular and systemic symptoms and comorbidities of the patients were also recorded.ResultsForty patients were included. The average time from the initiation of symptoms was 3.15 days. Unilateral conjunctivitis has been observed in 5% of patients and foreign body sensation in 7.5% of patients. No viral RNA was detected in the tear samples of the patients with ocular findings. The positivity rate for SARS-CoV-2 in tears was 2.5% (n = 1). None of the samples collected by Schirmer test strips yielded positive polymerase chain reaction result for SARS-COV-2. The Ct value of the positive conjunctival swab was 36.03 and the nasopharyngeal Ct value of the same patient was 25.68.ConclusionThe SARS-CoV-2 viral shedding rate has been determined as 2.5% in the tears of early symptomatic stage COVID-19 patients. The viral load of the tears was lower than the naso-oropharynx. The conjunctival swab method is recommended in tear collection to evaluate the presence of SARS-CoV-2 by RT-PCR analysis in low viral load tears.

Detailed characterizations of microstructure evolution, corrosion behavior and mechanical properties of refill friction stir spot welded 2219 aluminum alloy

2.0 mm thick 2219-O (upper plate) and 8.0 mm thick 2219-C10S (lower plate) were successfully fabricated using refill friction stir spot welding (RFSSW), and the microstructure evolution, corrosion behavior and mechanical properties of the joints were investigated. The results indicated that the stir zone (SZ) is characterized by refined and equiaxed grains due to dynamic recrystallization, whose grain size gradually increases, and the texture intensity decreases with the increase of the distance from the upper plate top surface. Tangled dislocations and dislocation cells are observed in the SZ, while rod-like precipitates with 20 nm–100 nm length are found in the base material (BM) of the lower plate. Also, numerous Al 2 Cu particles are observed in the upper plate BM, while only a few particles are aggregated in the lower plate BM. However, Al 2 Cu particles are fragmented and uniformly distributed in the SZ. The hardness of the upper plate and the lower plate is approximate 50 HV and 160 HV, respectively. The hardness increases gradually from top to bottom of the cross-section. The self-corrosion potential and corrosion current density of the SZ are −0.45 V and 5.62 × 10 −5 A/cm 2 , respectively. In comparison, those of the BM of the upper plate are −0.49 V and 3.16 × 10 −3 A/cm 2 , and those of the lower plate BM are −0.68 V and 7.94 × 10 −3 A/cm 2 . The electrochemical experiment indicated that the SZ presents excellent corrosion resistance, followed by upper plate BM and then lower plate BM. The corroded area has mainly occurred at the lower plate BM when the joint cross-section is immersed in the EXCO solution for one hour. However, upper and lower plate BMs are eroded seriously when the immersion time increases to two hours. Nevertheless, no obvious corrosion can be observed in the SZ. The mechanical analysis indicated that the tensile load decreases from 7.25 to 4.10 kN, and the tear load decreases from 3.20 to 1.78 kN after being immersed in the 3.5% NaCl solution for 48 h. • Refill friction stir spot welding technology has great advantages in joining aluminum alloys with unequal thickness. • The grains above the lap interface are equiaxed, while those below the lap interface are elongated. • The hardness increases gradually from the top to the bottom of the joint cross-section. • The corrosion resistance of SZ is the best, followed by upper plate BM and lower plate BM. • The tensile force decreases from 7.25 to 4.10 kN, and the tear force decreases from 3.20 to 1.78 kN after being immersed for 48 h.

Tearing behaviors of polytetrafluoroethylene coated fabric under uniaxial in-plane tearing tests

This study conducts alternative-basic-angle trapezoidal tearing and single-edge notch tearing tests on a polytetrafluoroethylene coated woven fabric, where the two methods are related through the basic angle of a trapezoid. The tearing process and failure modes are carefully examined, and load–displacement curves and tearing strength are analyzed. The tearing process comprises three stages, which are distinguished photographically or in different load–displacement curve sections. Corresponding to these stages, failure modes can be classified into three parts with varying extension directions. The effect of the basic angle is clearly illustrated. As the angle increases, three stages and parts appear in sequence; the tearing strength increases, but the larger one changes from weft to warp. The relationship between the tearing process and tearing strength is described. The three stages correspond to the increase in tearing strength, occurrence of the maximum tearing strength, and failure. Because the single-edge notch tearing method is more complex and important, it is the method that is studied mainly. Digital image correlation equipment is used to observe the strain distribution at the crack section. Moreover, the applications of four frequently used models are investigated. The results indicate that Thiele’s empirical formula offers the best simulation among the three tearing strength prediction models, and the theoretical stress distribution model also provides good simulation. Furthermore, a numerical simulation is conducted. The critical tearing strength and load–displacement curves before tearing initiates acquired through the simulation and test agree well. All results may provide basic data for future improvements in design theories.

Numerical simulation and experimental validation of triaxial woven fabric and its reinforced rubber composites on tear damage

In this article, the tear damage of triaxial woven fabric (TWF) and its reinforced rubber composites (TWFR) are investigated. Numerical simulation method for the yarn level is developed to predict the tear properties of samples with pre-cut in different directions, and the experiment method is used to verify the results of finite element analysis. It is analyzed that the changing law of tear load and the characteristics of tear failure during tear process. The results indicate that the load-displacement curve can be divided into low modulus region, high modulus region and shock region, which are related to initial stage, pre-cut opening stage and tear opening expansion stage the tear process of TWF and TWFR. When the pre-cut is parallel to the yarn, TWF and TWFR have higher tear load and larger tear starting position.

Bending fracture of ultra-thin plates with surface elasticity containing a thickness-through crack

The bending fracture of an ultra-thin plate containing a thickness-through crack with consideration of surface elasticity is studied in this paper. Based on the Kirchhoff plate theory incorporating surface elasticity, a governing equation is derived for static bending of nanoplates with surface elasticity. The fracture problem of an infinite isotropic elastic nanoplate with a thickness-through crack is presented and solved when the plate is subjected to uniform bending moment, twisting moment, and out-of-plane tearing load, respectively. The Fourier integral transform is applied to solve associated mixed boundary value problems. A hypersingular integral equation is deduced and an exact solution is determined for each case. Complete elastic fields at any position of the nanoplate are given explicitly in terms of elementary functions and the expressions for the intensity factors of stress, shear force, and bending/twisting moment at the crack tips are obtained in closed form. The intensity factors of stress and moment exhibit a square-root singularity, while the effective shear force intensity factors have an r-3/2 singularity near the crack tips, r being the distance from the crack tip. Results are presented graphically to show that the stress intensity factors (SIFs) are related to the bulk and surface material properties. When neglecting surface elasticity, the obtained size-dependent SIFs reduce to the well-known classical counterparts.

Adhesive Fracture Characteristic of DCB Specimen due to Single and Heterogeneous Materials under Tearing Load

Adhesive Fracture Characteristic of DCB Specimen due to Single and Heterogeneous Materials under Tearing Load

Study on hot cracking in laser welded joints of inconel 718 alloy foils

Pulsed laser welding was used to join ultra thin Inconel 718 alloy foils whose thickness was 0.2 mm. A fixture was designed to obtain the edge joint. The joint geometry and hot cracking were both observed on the cross sections. The relationship between the height, width of the joint and the energy density were fitted as linear functions. The effect of heat input on the hot cracking in the edge joint was obtained. It was shown that a hot cracking occurred during the solidification of the molten metal under laser heating. The crack initiated at the gap between the foil pair and propagated along the Laves phase with low melting point. The crack length could be reduced by applying low heat input. Tearing tests were conducted to evaluate the influence of the cracking on the mechanical performance of edge joints. There existed two failure modes for the edge joint under a tear loading. When the crack length exceeds 106.9 μm the hot crack starts to propagate and the tear loading decreases with crack length increasing. A finite element model was established to simulate the stress evolution during the cooling stage. The main reason of crack initiation and propagation were both presented.

Role of Eyes and Eyes Protection Amidst SARS-CoV-2 Infection.

Severe Acute Respiratory Syndrome Coronavirus 2 pandemic has infected millions of people. The conjunctival epithelium is easily exposed to infectious droplets and body fluids making eyes a potential route and reservoir of the infection. The CD147 and ACE2 receptor has been demonstrated in ocular surface cells, which implies that these cells may facilitate as a portal of entry for transmission of Severe Acute Respiratory Syndrome Coronavirus 2. Despite low viral load in tears and conjunctival swab, the negative RT-PCR results cannot exclude the possibility of the presence of Severe Acute Respiratory Syndrome Coronavirus 2 in ocular secretions. Pathogens might be transported by constant tear flow through the lacrimal duct system to the respiratory tract causing infection. Eyes are unlikely to be the main transmission route, however, their role in the transmission of Severe Acute Respiratory Syndrome Coronavirus 2 cannot be overlooked. Therefore, proper eye protection should be instituted while attending Severe Acute Respiratory Syndrome Coronavirus 2 positive individuals, especially by health professionals.

Effect of the viscosity of polyvinyl chloride resin and weaving structures of polyester fabric on the off-axis mechanical properties of PVC coated fabric

PVC coated fabric is a useful structural material mainly used as a roof material because of its lightweight, flexibility. However, the main issues of this PVC coated fabric product is that it is damaged such as tensile failure, peel, and tear when exposed to extreme environments such as strong rain and wind owing to its inferior mechanical properties. Various studies have been reported to improve the mechanical properties of PVC coated fabric, there have been no significant improvement. Therefore, in this study, to improve the mechanical properties of the PVC coated fabrics, applied the low viscosity PVC resin and 4 [Formula: see text] 4 matt weave structure polyester fabric. In addition, the mechanical properties of PVC coated fabrics with various viscosity PVC resins (D10, D8, D5, D2 and D0) were investigated and the mechanical properties of PVC coated fabrics with various weaving structure such as plain weave structure (1 [Formula: see text] 1), matt weave structure (2 [Formula: see text] 2, 3[Formula: see text] 3, and 4 [Formula: see text] 4) were studied. The PVC coated fabric fabricated by low viscosity PVC resin (D10), the tensile strength, tear load, and peel strength improved about 3%, 11%, and 29% compared to the PVC coated fabric fabricated by high viscosity PVC resin (D0). The mechanical properties of the PVC coated fabric fabricated by 4 × 4 matt weave structure polyester fabric was superior to the 1 × 1 plain weave structure polyester fabric and 2 × 2, 3 × 3 matt weave structure polyester fabrics because of the low crimp rate and low intersection point of the warp yarn and weft yarn of the fabric.