The service life of a facial prosthesis is about six months as a result of the impairment in its mechanical or physical properties;thus,introducing a new reinforced maxillofacial silicone material can help in fabricat...The service life of a facial prosthesis is about six months as a result of the impairment in its mechanical or physical properties;thus,introducing a new reinforced maxillofacial silicone material can help in fabricating a long service life prosthesis that eliminates the burden for the patients both financially and psychologically.In this study,forty samples were fabricated by adding different concentrations of CaCO_(3)-SiO_(2) nanoparticles composite to maxillofacial silicone elastomer.These samples were divided into four groups,each one containing ten samples according to the concentration of the fillers(0%,1%,2%and 3%).All samples were tested for tear strength and hardness tests.The study results show that CaCO_(3)-SiO_(2) nanoparticles composite has a significant effect on both conducted tests.It can be concluded that reinforcing the silicone matrix with 2%CaCO_(3)-SiO_(2) nanoparticles composite can improve the tear strength of the tested silicone and increase its hardness.展开更多
The nonwoven composites have sandwich structure, with the first and third layers being nonwovens and the middle layer of woven fabric. On the basis of tests of the single rip tearing strength and drawing out resistanc...The nonwoven composites have sandwich structure, with the first and third layers being nonwovens and the middle layer of woven fabric. On the basis of tests of the single rip tearing strength and drawing out resistances of both the nonwoven composites and the woven fabric, the single rip tearing failure mechanism of the composites were analyzed. Then theoretical calculation model for the single rip tearing strength was established, which indicates that the breaking strength of warp and weft yams in the nonwoven composites, the density of warp and weft yarns and drawing out resistances are the main influencing factors. In the end, experimental verification was made, which shows that theoretical values conform to the measured values well.展开更多
With the increasingly widespread application of rubber in many fields,there is a growing demand for quantitative characterization of temperature-dependent mechanical properties in high-temperature service environments...With the increasingly widespread application of rubber in many fields,there is a growing demand for quantitative characterization of temperature-dependent mechanical properties in high-temperature service environments.The critical tearing energy is an important criterion for determining whether rubber materials will experience tearing instability,while tear strength is a key parameter for rubber materials to resist tearing.It is necessary to quantitatively characterize their evolution with temperature.Current theoretical research mainly relies on fitting a large amount of experimental data,which is not convenient for engineering applications.Therefore,in this work,a temperature-dependent critical tearing energy model is firstly developed based on the force-heat equivalence energy density principle.This model considers the equivalent relationship between the critical tearing energy required for crack instability propagation and the thermal energy stored in the rubber material.It is demonstrated that our model has higher prediction accuracy when compared to other models.Furthermore,combining with the Griffith fracture theory,temperature-dependent tear strength models applicable to three different crack modes are separately established.These models are validated using experimental data for Mode I opening cracks and ModeⅢtearing cracks,and good consistency is achieved.Additionally,a quantitative analysis of the influence of elastic modulus on tear strength at different temperatures is conducted.This work provides a reliable way for predicting temperature-dependent tearing instability behavior and offers beneficial suggestions for improving the tear strength of rubber materials at different temperatures.展开更多
Day by day, the demand and popularity of denim have increased. With the increase in demand for denim, washing has also increased. When we washed a piece of denim fabric, then its properties also changed. The propertie...Day by day, the demand and popularity of denim have increased. With the increase in demand for denim, washing has also increased. When we washed a piece of denim fabric, then its properties also changed. The properties are tensile strength, GSM, color fading, stiffness, abrasion resistance, moisture regain, etc. In this study, we conduct different washing processes on denim fabric such are Stonewash, Caustic wash, Acid wash, Normal wash, Pigment wash, Sandblasting, and Super whitewash. After washing, the properties of denim fabric have been analyzed especially strength. The tear and tensile strength were measured by ISO standard. From the above washing method, Normal & pigment wash showed good strength properties comparing with others.展开更多
In this paper,an equation expressing relationship between trapezoid tear strength and fabrictensile properties,weave texture and geomitry of specimen was studied.It could be used to predicttrapezoid tear strength for ...In this paper,an equation expressing relationship between trapezoid tear strength and fabrictensile properties,weave texture and geomitry of specimen was studied.It could be used to predicttrapezoid tear strength for uncoated fabrics well,and also for coated fabrics if multipling a stressconcentration coefficient.The four tear test standard methods(single-rip,double-rip,wing-ripand trapezoid tear)have been adopted to measure the tear strength of fifteen coated fabrics whichwere used for architecture and gencral industrial purposes and the nine corresponding uncoatedfabrics respectively.Analysis and comparison of experimental results showed that there are an ex-cellent correlation between each two methods with the four tear parameters respectively and a goodconsistency of the order of the tear strength for different samples.In addition,the experimental results showed that a good correlation exists between the tenslieproperties and tear strength of coated and uncoated fabrics.展开更多
Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there ...Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there are several problems especially the low ductility and toughness, which have restricted the application of HSHSS in automobile body. Suitable process parameters are very crucial to improve strength and toughness. In order to study the effect of austenization temperature, soaking time and start deformation temperature on strength and toughness of boron steel 22MnB5, an L9 （34） orthogonal experiment which was analyzed by means of comprehensive evaluation was carried out based on Kahn tear method to obtain the value of fracture toughness. The results indicate that the ex- cellent formability, high strength and toughness of boron steel 22MnB5 with 1.6 mm in thickness are obtained when the austenization temperature is in the range of 920- 950 ℃, the soaking time is 1 min and the start deformation temperature is in the range of 650- 700 ℃. The optimal parameters were used for typical hot stamping structural parts tests. Properties of samples such as tear strength, unit initiation energy and ratio of strength to toughness （RST） were improved by 10.91%, 20.32% and 22.17%, respectively. Toughness was increased substantially on the basis of a small decrease of strength.展开更多
The specification of laid-in and warp yams,thedensity of fabric and the specification of groundyam are of great importance when the bi-axialwarp knitted fabric being knitted.In this paper,the tearing property of the r...The specification of laid-in and warp yams,thedensity of fabric and the specification of groundyam are of great importance when the bi-axialwarp knitted fabric being knitted.In this paper,the tearing property of the reinforced plastic filmwith bi-axial warp knitted fabric skeleton istested and analyzed.The resuits show thatamong the three factors,the specification of laid-in and warp yam has the greatest influence onthe tearing strength of the reinforced plastic film,while the rest of them has secondary and lesseffect respectively,and there is exponential re-lation between the tearing strength of the rein-forced plastic film and the number of yams in thedirection of force.展开更多
This work seeks to investigate the notch sensitivity and fracture behaviour of orthogonal Kevlar-plain woven fabric （PWF）-reinforced thermoplastic polyurethanes （TPU） film applied to high altitude balloon. Four ty...This work seeks to investigate the notch sensitivity and fracture behaviour of orthogonal Kevlar-plain woven fabric （PWF）-reinforced thermoplastic polyurethanes （TPU） film applied to high altitude balloon. Four types of specimens are implemented to measure notched strength and fracture toughness by conducting static tension and tear tests on an MTS system respectively. The damage and failure mechanisms are discussed and the results for notched strength and tear resistance are evaluated and compared with each other. From the experiments, it is found that the notch sensitivity of the film increases with the increase in the size of the hole, but the notch sensitivity and the stress concentration of the notch are insignificant and there is a decrease of only about 4%-10% in tensile strength for the notched specimens with different hole sizes in diameter compared with the unnotched specimen. In contrast, the tear resistance containing a central slit with only 1 mm length is about half of tensile strength of the unnotched film, which implies that the tear resistance exists an significant notch sensitivity. The results of this study provide an insight into notch sensitivity and fracture behaviour of the Kevlar-PWF-reinforced TPU film and constitute a fundamental basis for the design of high altitude balloon.展开更多
A new parameter, i.e., tearing toughness, was employed to characterize the mechanical properties of some ductile metals （Cu, Cu-2 wt% Be, Cu-Al alloys, and some steels） by using three-leg trousers tearing tests. The...A new parameter, i.e., tearing toughness, was employed to characterize the mechanical properties of some ductile metals （Cu, Cu-2 wt% Be, Cu-Al alloys, and some steels） by using three-leg trousers tearing tests. The experi- mental results demonstrate that their tearing toughness is not a physical constant and shows a close relationship with the materials＇ types and microstructures. It can be inferred that the tearing toughness of different ductile metals has their respective variation range, expectantly, and may be represented by the comprehensive mechanical properties of strength and ductility for various ductile materials.展开更多
文摘The service life of a facial prosthesis is about six months as a result of the impairment in its mechanical or physical properties;thus,introducing a new reinforced maxillofacial silicone material can help in fabricating a long service life prosthesis that eliminates the burden for the patients both financially and psychologically.In this study,forty samples were fabricated by adding different concentrations of CaCO_(3)-SiO_(2) nanoparticles composite to maxillofacial silicone elastomer.These samples were divided into four groups,each one containing ten samples according to the concentration of the fillers(0%,1%,2%and 3%).All samples were tested for tear strength and hardness tests.The study results show that CaCO_(3)-SiO_(2) nanoparticles composite has a significant effect on both conducted tests.It can be concluded that reinforcing the silicone matrix with 2%CaCO_(3)-SiO_(2) nanoparticles composite can improve the tear strength of the tested silicone and increase its hardness.
文摘The nonwoven composites have sandwich structure, with the first and third layers being nonwovens and the middle layer of woven fabric. On the basis of tests of the single rip tearing strength and drawing out resistances of both the nonwoven composites and the woven fabric, the single rip tearing failure mechanism of the composites were analyzed. Then theoretical calculation model for the single rip tearing strength was established, which indicates that the breaking strength of warp and weft yams in the nonwoven composites, the density of warp and weft yarns and drawing out resistances are the main influencing factors. In the end, experimental verification was made, which shows that theoretical values conform to the measured values well.
基金the National Natural Science Foundation of China(12172069)the Graduate Scientific Research and Innovation Foundation of Chongqing(CYS23078)for their support in this research.
文摘With the increasingly widespread application of rubber in many fields,there is a growing demand for quantitative characterization of temperature-dependent mechanical properties in high-temperature service environments.The critical tearing energy is an important criterion for determining whether rubber materials will experience tearing instability,while tear strength is a key parameter for rubber materials to resist tearing.It is necessary to quantitatively characterize their evolution with temperature.Current theoretical research mainly relies on fitting a large amount of experimental data,which is not convenient for engineering applications.Therefore,in this work,a temperature-dependent critical tearing energy model is firstly developed based on the force-heat equivalence energy density principle.This model considers the equivalent relationship between the critical tearing energy required for crack instability propagation and the thermal energy stored in the rubber material.It is demonstrated that our model has higher prediction accuracy when compared to other models.Furthermore,combining with the Griffith fracture theory,temperature-dependent tear strength models applicable to three different crack modes are separately established.These models are validated using experimental data for Mode I opening cracks and ModeⅢtearing cracks,and good consistency is achieved.Additionally,a quantitative analysis of the influence of elastic modulus on tear strength at different temperatures is conducted.This work provides a reliable way for predicting temperature-dependent tearing instability behavior and offers beneficial suggestions for improving the tear strength of rubber materials at different temperatures.
文摘Day by day, the demand and popularity of denim have increased. With the increase in demand for denim, washing has also increased. When we washed a piece of denim fabric, then its properties also changed. The properties are tensile strength, GSM, color fading, stiffness, abrasion resistance, moisture regain, etc. In this study, we conduct different washing processes on denim fabric such are Stonewash, Caustic wash, Acid wash, Normal wash, Pigment wash, Sandblasting, and Super whitewash. After washing, the properties of denim fabric have been analyzed especially strength. The tear and tensile strength were measured by ISO standard. From the above washing method, Normal & pigment wash showed good strength properties comparing with others.
文摘In this paper,an equation expressing relationship between trapezoid tear strength and fabrictensile properties,weave texture and geomitry of specimen was studied.It could be used to predicttrapezoid tear strength for uncoated fabrics well,and also for coated fabrics if multipling a stressconcentration coefficient.The four tear test standard methods(single-rip,double-rip,wing-ripand trapezoid tear)have been adopted to measure the tear strength of fifteen coated fabrics whichwere used for architecture and gencral industrial purposes and the nine corresponding uncoatedfabrics respectively.Analysis and comparison of experimental results showed that there are an ex-cellent correlation between each two methods with the four tear parameters respectively and a goodconsistency of the order of the tear strength for different samples.In addition,the experimental results showed that a good correlation exists between the tenslieproperties and tear strength of coated and uncoated fabrics.
基金Sponsored by National Natural Science Foundation of China(50901011,10932003)National Basic Research Project of China(2010CB832700)+1 种基金"04"Great Project of Ministry of Industrialization and Information of China(2011ZX04001-21)Fundamental Research Funds for Central Universities of China(DUT12LK03)
文摘Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there are several problems especially the low ductility and toughness, which have restricted the application of HSHSS in automobile body. Suitable process parameters are very crucial to improve strength and toughness. In order to study the effect of austenization temperature, soaking time and start deformation temperature on strength and toughness of boron steel 22MnB5, an L9 （34） orthogonal experiment which was analyzed by means of comprehensive evaluation was carried out based on Kahn tear method to obtain the value of fracture toughness. The results indicate that the ex- cellent formability, high strength and toughness of boron steel 22MnB5 with 1.6 mm in thickness are obtained when the austenization temperature is in the range of 920- 950 ℃, the soaking time is 1 min and the start deformation temperature is in the range of 650- 700 ℃. The optimal parameters were used for typical hot stamping structural parts tests. Properties of samples such as tear strength, unit initiation energy and ratio of strength to toughness （RST） were improved by 10.91%, 20.32% and 22.17%, respectively. Toughness was increased substantially on the basis of a small decrease of strength.
文摘The specification of laid-in and warp yams,thedensity of fabric and the specification of groundyam are of great importance when the bi-axialwarp knitted fabric being knitted.In this paper,the tearing property of the reinforced plastic filmwith bi-axial warp knitted fabric skeleton istested and analyzed.The resuits show thatamong the three factors,the specification of laid-in and warp yam has the greatest influence onthe tearing strength of the reinforced plastic film,while the rest of them has secondary and lesseffect respectively,and there is exponential re-lation between the tearing strength of the rein-forced plastic film and the number of yams in thedirection of force.
基金National Natural Science Foundation of China (E050603)Aeronautical Science Foundation of China (20095251024)
文摘This work seeks to investigate the notch sensitivity and fracture behaviour of orthogonal Kevlar-plain woven fabric （PWF）-reinforced thermoplastic polyurethanes （TPU） film applied to high altitude balloon. Four types of specimens are implemented to measure notched strength and fracture toughness by conducting static tension and tear tests on an MTS system respectively. The damage and failure mechanisms are discussed and the results for notched strength and tear resistance are evaluated and compared with each other. From the experiments, it is found that the notch sensitivity of the film increases with the increase in the size of the hole, but the notch sensitivity and the stress concentration of the notch are insignificant and there is a decrease of only about 4%-10% in tensile strength for the notched specimens with different hole sizes in diameter compared with the unnotched specimen. In contrast, the tear resistance containing a central slit with only 1 mm length is about half of tensile strength of the unnotched film, which implies that the tear resistance exists an significant notch sensitivity. The results of this study provide an insight into notch sensitivity and fracture behaviour of the Kevlar-PWF-reinforced TPU film and constitute a fundamental basis for the design of high altitude balloon.
基金financially supported by the National Natural Science Foundation of China(NSFC)under Grant No.51331007
文摘A new parameter, i.e., tearing toughness, was employed to characterize the mechanical properties of some ductile metals （Cu, Cu-2 wt% Be, Cu-Al alloys, and some steels） by using three-leg trousers tearing tests. The experi- mental results demonstrate that their tearing toughness is not a physical constant and shows a close relationship with the materials＇ types and microstructures. It can be inferred that the tearing toughness of different ductile metals has their respective variation range, expectantly, and may be represented by the comprehensive mechanical properties of strength and ductility for various ductile materials.
