Pub Date : 2024-03-26DOI: 10.1177/14644207241241799
Pedro Nogueira, João PG Magrinho, Maria B Silva, Augusto M de Deus, Maria F Vaz
Recently, cellular materials made by the repetition of unit cells, that is, iron lattices have become appealing to mimic the structure of bone. The aim of the study is to choose the most adequate lattice structures, which have the compressive mechanical properties closer to the ones of bone, in the perspective of their use as temporary implants. Five types of unit cells were selected, such as, cubic (C), truncated octahedron (TO), truncated cubic (TC), rhombicuboctahedron (RCO), and rhombitrucated cuboctahedron (RTCO). The mechanical properties were assessed by numerical simulations with a finite-element analysis. The size effect was studied with the comparison of results among samples with different numbers of unit cells. Simulations covered a wide range of relative densities. Graded dense-in and dense-out configurations were constructed with lattices of types RTCO and TO, being the unit cells, themselves graded. Lattice structures RTCO and TO were found to be stable at every relative density studied, while C, TC and RCO lattices are unstable at low densities. The evaluation of size effects was not conclusive, which could be biased by other factors. The Young's modulus of RTCO and TO lattices enable to reproduce the properties of both trabecular and cortical bone, with an appropriate choice of the relative density. To mimic trabecular bone, only RTCO and TO structures with low relative densities, can be used, while arrangements of C, TC and RCO cells can only replicate the properties of cortical bone. Graded cells may have the same properties as non-graded with lower density.
最近，通过重复单元格（即铁晶格）制成的细胞材料在模仿骨骼结构方面颇具吸引力。这项研究的目的是选择最合适的晶格结构，使其具有更接近骨骼的压缩机械性能，以用作临时植入物。我们选择了五种单元格，如立方体（C）、截断八面体（TO）、截断立方体（TC）、菱形立方体（RCO）和菱形截断立方体（RTCO）。通过有限元分析的数值模拟对其机械性能进行了评估。通过比较具有不同单元格数的样品的结果，研究了尺寸效应。模拟涵盖了广泛的相对密度范围。利用 RTCO 和 TO 类型的晶格构建了分级密入和密出配置，这些晶格是本身分级的单元格。研究发现，RTCO 和 TO 晶格结构在每个相对密度下都是稳定的，而 C、TC 和 RCO 晶格在低密度下则不稳定。对尺寸效应的评估没有得出结论，这可能受到其他因素的影响。只要适当选择相对密度，RTCO 和 TO 晶格的杨氏模量就能再现骨小梁和皮质骨的特性。要模拟骨小梁，只能使用相对密度较低的 RTCO 和 TO 结构，而 C、TC 和 RCO 细胞的排列只能复制皮质骨的特性。分级细胞的特性可能与密度较低的非分级细胞相同。
{"title":"Compression properties of cellular iron lattice structures used to mimic bone characteristics","authors":"Pedro Nogueira, João PG Magrinho, Maria B Silva, Augusto M de Deus, Maria F Vaz","doi":"10.1177/14644207241241799","DOIUrl":"https://doi.org/10.1177/14644207241241799","url":null,"abstract":"Recently, cellular materials made by the repetition of unit cells, that is, iron lattices have become appealing to mimic the structure of bone. The aim of the study is to choose the most adequate lattice structures, which have the compressive mechanical properties closer to the ones of bone, in the perspective of their use as temporary implants. Five types of unit cells were selected, such as, cubic (C), truncated octahedron (TO), truncated cubic (TC), rhombicuboctahedron (RCO), and rhombitrucated cuboctahedron (RTCO). The mechanical properties were assessed by numerical simulations with a finite-element analysis. The size effect was studied with the comparison of results among samples with different numbers of unit cells. Simulations covered a wide range of relative densities. Graded dense-in and dense-out configurations were constructed with lattices of types RTCO and TO, being the unit cells, themselves graded. Lattice structures RTCO and TO were found to be stable at every relative density studied, while C, TC and RCO lattices are unstable at low densities. The evaluation of size effects was not conclusive, which could be biased by other factors. The Young's modulus of RTCO and TO lattices enable to reproduce the properties of both trabecular and cortical bone, with an appropriate choice of the relative density. To mimic trabecular bone, only RTCO and TO structures with low relative densities, can be used, while arrangements of C, TC and RCO cells can only replicate the properties of cortical bone. Graded cells may have the same properties as non-graded with lower density.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"46 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-26DOI: 10.1177/14644207241240642
M Gamerdinger, M Clemens, S Olschok, U Reisgen
One possible option for increasing the fatigue strength of welded joints is the use of so-called low transformation temperature (LTT) alloys. The aim is to introduce residual compressive stresses into the weld to counteract crack initiation and propagation. Until now, there has been no application of an LTT effect to high-performance welding processes such as the laser beam submerged arc hybrid welding process (LUPuS hybrid). First, the LUPuS hybrid single-wire process was further developed into the LUPuS tandem hybrid process. This makes it possible to equip the two submerged arc welding torches with different commercially available filler wires. The aim of the work is to further develop the LUPuS tandem hybrid welding process to enable the use of the LTT effect. The in situ alloying process for obtaining the LTT effect from commercially available material combinations was extended to the two-wire process. The alloy obtained was investigated by means of energy dispersive x-ray spectroscopy and hardness measurements and the influence on residual stresses was determined by the borehole method supported by electronic speckle pattern interferometry.
{"title":"Development of an in situ alloying method for high-performance welding processes to achieve an LTT effect by local modification of the alloy content","authors":"M Gamerdinger, M Clemens, S Olschok, U Reisgen","doi":"10.1177/14644207241240642","DOIUrl":"https://doi.org/10.1177/14644207241240642","url":null,"abstract":"One possible option for increasing the fatigue strength of welded joints is the use of so-called low transformation temperature (LTT) alloys. The aim is to introduce residual compressive stresses into the weld to counteract crack initiation and propagation. Until now, there has been no application of an LTT effect to high-performance welding processes such as the laser beam submerged arc hybrid welding process (LUPuS hybrid). First, the LUPuS hybrid single-wire process was further developed into the LUPuS tandem hybrid process. This makes it possible to equip the two submerged arc welding torches with different commercially available filler wires. The aim of the work is to further develop the LUPuS tandem hybrid welding process to enable the use of the LTT effect. The in situ alloying process for obtaining the LTT effect from commercially available material combinations was extended to the two-wire process. The alloy obtained was investigated by means of energy dispersive x-ray spectroscopy and hardness measurements and the influence on residual stresses was determined by the borehole method supported by electronic speckle pattern interferometry.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"71 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-25DOI: 10.1177/14644207241240623
Gagan Bansal, Rakesh Kumar Gautam, Joy Prakash Misra, Abhilasha Mishra
Polymethylmethacrylate (PMMA) and hydroxyapatite (HAp) are the two most promising biocompatible materials used in biomedical applications. The current research performs the wettability and tribological characterization of the novel hybrid biocomposite of PMMA reinforced with eggshell-derived, silver-doped hydroxyapatite (HAPAg). Varying wt% of HAPAg in PMMA were analyzed using a ball-on-disk tribometer. The coefficient of friction shows an increasing trend with an increase in normal load for all the compositions while, with reinforcement of HAPAg, it increases till 5 wt% and then shows a sudden decrement at PHA7.5 due to the formation of flattened asperities at the contact surface. However, the progressive increase in hardness with the inclusion of HAPAg in PMMA correlates with the reduction in the wear rate of the composite samples. The highest wear rate was observed for PHA0 (i.e. 862.42 × 10−5 mm3/m) at 60 N. As observed, the hydrophilicity increases (contact angle changed from 96.30° ± 2.11° [PHA0] to 81.70° ± 1.01° [PHA7.5]), and the porosity decreases (≈2.86%) with the reinforcement of HAPAg in PMMA which further improves the cohesion strength and microhardness of the composite material. The X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis confirms the uniform reinforcement of HAPAg, and the worn surface behavior was inspected using scanning electron microscopy, Stereo zoom microscope, and three-dimensional surface profilometer. The low-specific wear characteristic at higher loads ensures the application of developed biocomposite material in dental and orthopedic applications.
{"title":"Tribological behavior of silver-doped eggshell-derived hydroxyapatite reinforcement in PMMA-based composite","authors":"Gagan Bansal, Rakesh Kumar Gautam, Joy Prakash Misra, Abhilasha Mishra","doi":"10.1177/14644207241240623","DOIUrl":"https://doi.org/10.1177/14644207241240623","url":null,"abstract":"Polymethylmethacrylate (PMMA) and hydroxyapatite (HAp) are the two most promising biocompatible materials used in biomedical applications. The current research performs the wettability and tribological characterization of the novel hybrid biocomposite of PMMA reinforced with eggshell-derived, silver-doped hydroxyapatite (HAPAg). Varying wt% of HAPAg in PMMA were analyzed using a ball-on-disk tribometer. The coefficient of friction shows an increasing trend with an increase in normal load for all the compositions while, with reinforcement of HAPAg, it increases till 5 wt% and then shows a sudden decrement at PHA7.5 due to the formation of flattened asperities at the contact surface. However, the progressive increase in hardness with the inclusion of HAPAg in PMMA correlates with the reduction in the wear rate of the composite samples. The highest wear rate was observed for PHA0 (i.e. 862.42 × 10<jats:sup>−5</jats:sup> mm<jats:sup>3</jats:sup>/m) at 60 N. As observed, the hydrophilicity increases (contact angle changed from 96.30° ± 2.11° [PHA0] to 81.70° ± 1.01° [PHA7.5]), and the porosity decreases (≈2.86%) with the reinforcement of HAPAg in PMMA which further improves the cohesion strength and microhardness of the composite material. The X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis confirms the uniform reinforcement of HAPAg, and the worn surface behavior was inspected using scanning electron microscopy, Stereo zoom microscope, and three-dimensional surface profilometer. The low-specific wear characteristic at higher loads ensures the application of developed biocomposite material in dental and orthopedic applications.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"86 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140297874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-25DOI: 10.1177/14644207241241156
Ali I Ansari, Nazir A Sheikh, Navin Kumar, Jyotendra Nath
When treating orthopaedic damage or illness and accidental fracture, bone grafting remains the gold standard of treatment. In cases where this approach doesn't seem achievable, bone tissue engineering can offer scaffolding as a substitute. Defective and fractured bone tissue is extracted and substituted with porous scaffold structures to aid in the process of tissue regeneration. Three-dimensional bioprinting has demonstrated enormous promise in recent years for producing scaffold structures with the necessary capabilities. In order to create composite biomaterial inks for three-dimensional bioprinting, four different materials were combined such as silk fibroin, bone particles (B), synthetic biopolymer poly (ε-caprolactone), and Fenugreek (F). These biomaterials were mixed together in certain proportion to develop a silk fibroin + bovine bone + polycaprolactone + fenugreek powder composites biomaterial which was later three-dimensional bioprinted to fabricated composite bio-scaffold. The biomechanical, structural, and biological elements of the manufactured composite scaffolds were characterized in order to determine their suitability as a possible biomaterial for the production of bone tissue. The in vitro bioactivity of the composite scaffolds was assessed in the simulated body fluids, and the swelling and degradation characteristics of the two developed scaffolds were analyzed separately over time. The results showed that the mechanical durability of the composite scaffolds was enhanced by the bovine bone particles, up to a specific concentration in the silk fibroin matrix. Furthermore, the incorporation of bone particles improved the bioactive composite scaffolds’ capacity to generate hydroxyapatite in vitro. The combined findings show that the three-dimensional printed bio-composites scaffolds have the required mechanical strength and may be applied to regeneration of bone tissue and restoration, since they resemble the characteristics of native bone.
{"title":"Three-dimensional printed silk fibroin and fenugreek based bio-composites scaffolds","authors":"Ali I Ansari, Nazir A Sheikh, Navin Kumar, Jyotendra Nath","doi":"10.1177/14644207241241156","DOIUrl":"https://doi.org/10.1177/14644207241241156","url":null,"abstract":"When treating orthopaedic damage or illness and accidental fracture, bone grafting remains the gold standard of treatment. In cases where this approach doesn't seem achievable, bone tissue engineering can offer scaffolding as a substitute. Defective and fractured bone tissue is extracted and substituted with porous scaffold structures to aid in the process of tissue regeneration. Three-dimensional bioprinting has demonstrated enormous promise in recent years for producing scaffold structures with the necessary capabilities. In order to create composite biomaterial inks for three-dimensional bioprinting, four different materials were combined such as silk fibroin, bone particles (B), synthetic biopolymer poly (ε-caprolactone), and Fenugreek (F). These biomaterials were mixed together in certain proportion to develop a silk fibroin + bovine bone + polycaprolactone + fenugreek powder composites biomaterial which was later three-dimensional bioprinted to fabricated composite bio-scaffold. The biomechanical, structural, and biological elements of the manufactured composite scaffolds were characterized in order to determine their suitability as a possible biomaterial for the production of bone tissue. The in vitro bioactivity of the composite scaffolds was assessed in the simulated body fluids, and the swelling and degradation characteristics of the two developed scaffolds were analyzed separately over time. The results showed that the mechanical durability of the composite scaffolds was enhanced by the bovine bone particles, up to a specific concentration in the silk fibroin matrix. Furthermore, the incorporation of bone particles improved the bioactive composite scaffolds’ capacity to generate hydroxyapatite in vitro. The combined findings show that the three-dimensional printed bio-composites scaffolds have the required mechanical strength and may be applied to regeneration of bone tissue and restoration, since they resemble the characteristics of native bone.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"47 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140297873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-22DOI: 10.1177/14644207241239587
Danial Kordzangeneh, Hadi Khoramishad, Amir Reza Fatolahi
Epoxy resin as a thermoset polymer is vulnerable to creep loading even at room temperature due to its viscoelastic nature. This study investigated the effect of reinforcing epoxy resin with different functionalized multi-walled carbon nanotubes (MWCNT) contents on the creep response and post-creep residual tensile properties of nanocomposites. The creep tests were performed on the nanocomposite specimens containing different filler contents and the neat epoxy specimen at 40°C under a constant load level of 200 N. It was found that the nanocomposites containing 0.3 wt% MWCNTs experienced 29.6%, 69.1%, and 74.1% decreases in the elastic strain, creep strain, and steady-state creep strain rate, respectively, compared to the neat epoxy. Furthermore, the tensile strength and stiffness of the neat epoxy and nanocomposite specimens were evaluated before and after a partial creep test (at a load level of 200 N for 150 min) by conducting tensile tests. The nanocomposites containing 0.3 wt% MWCNTs demonstrated considerable improvements of 35.9%, 41.2%, 27.9%, and 28.1% in strength, residual strength, stiffness, and residual stiffness, respectively, compared to the neat epoxy. Furthermore, scanning electron microscopy assessment was utilized to investigate the fracture surfaces of the nanocomposite specimens.
{"title":"Post-creep residual tensile properties of multi-walled carbon nanotube/epoxy nanocomposites","authors":"Danial Kordzangeneh, Hadi Khoramishad, Amir Reza Fatolahi","doi":"10.1177/14644207241239587","DOIUrl":"https://doi.org/10.1177/14644207241239587","url":null,"abstract":"Epoxy resin as a thermoset polymer is vulnerable to creep loading even at room temperature due to its viscoelastic nature. This study investigated the effect of reinforcing epoxy resin with different functionalized multi-walled carbon nanotubes (MWCNT) contents on the creep response and post-creep residual tensile properties of nanocomposites. The creep tests were performed on the nanocomposite specimens containing different filler contents and the neat epoxy specimen at 40°C under a constant load level of 200 N. It was found that the nanocomposites containing 0.3 wt% MWCNTs experienced 29.6%, 69.1%, and 74.1% decreases in the elastic strain, creep strain, and steady-state creep strain rate, respectively, compared to the neat epoxy. Furthermore, the tensile strength and stiffness of the neat epoxy and nanocomposite specimens were evaluated before and after a partial creep test (at a load level of 200 N for 150 min) by conducting tensile tests. The nanocomposites containing 0.3 wt% MWCNTs demonstrated considerable improvements of 35.9%, 41.2%, 27.9%, and 28.1% in strength, residual strength, stiffness, and residual stiffness, respectively, compared to the neat epoxy. Furthermore, scanning electron microscopy assessment was utilized to investigate the fracture surfaces of the nanocomposite specimens.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"31 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140202641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-19DOI: 10.1177/14644207241238429
Luís Aser Portela, Etienne Copin, M Fátima Vaz, Augusto M Deus
The dissemination of additive manufacturing methods has facilitated the design and production of complex structures which have a high strength-to-weight ratio. Cellular materials such as honeycombs have low-weight and high capacity to absorb energy which makes them desirable for the aerospace and automotive industries. The present work covers the study and comparison of metal-based regular honeycombs and functionally graded honeycombs. The latter encompass radial and linear/longitudinal gradients. Three repeating unit cells were studied: regular hexagons, Plateau and lotus. The structures were produced in aluminium using the laser powder bed fusion technique. Selected samples were submitted to a stress-relieving heat treatment. Numerical and experimental methods were used to assess the in-plane compressive properties. Finite element analysis was used to obtain the simulated force–displacement curves of each structure, allowing for the calculation of specific stiffness, absorbed energy and yield strength. The experimental method consisted of the compression of three specimens of three types of regular structures with and without stress-relieving heat treatment. The heat treatment reduced the yield strength and stiffness whilst increasing the ductility of the samples. The mechanical behaviour of the structures was found to depend upon a combined effect of the type of gradient, relative density, and unit cell structure. The results showed that an increase in the relative density would enhance the specific mechanical properties. The lotus configuration displayed the highest specific mechanical properties, as its geometry reduces the stress concentrations. The numerical results showed a reasonable match with the experimental results.
{"title":"Modelling and characterization of novel honeycomb structures with mass gradient produced by additive manufacturing","authors":"Luís Aser Portela, Etienne Copin, M Fátima Vaz, Augusto M Deus","doi":"10.1177/14644207241238429","DOIUrl":"https://doi.org/10.1177/14644207241238429","url":null,"abstract":"The dissemination of additive manufacturing methods has facilitated the design and production of complex structures which have a high strength-to-weight ratio. Cellular materials such as honeycombs have low-weight and high capacity to absorb energy which makes them desirable for the aerospace and automotive industries. The present work covers the study and comparison of metal-based regular honeycombs and functionally graded honeycombs. The latter encompass radial and linear/longitudinal gradients. Three repeating unit cells were studied: regular hexagons, Plateau and lotus. The structures were produced in aluminium using the laser powder bed fusion technique. Selected samples were submitted to a stress-relieving heat treatment. Numerical and experimental methods were used to assess the in-plane compressive properties. Finite element analysis was used to obtain the simulated force–displacement curves of each structure, allowing for the calculation of specific stiffness, absorbed energy and yield strength. The experimental method consisted of the compression of three specimens of three types of regular structures with and without stress-relieving heat treatment. The heat treatment reduced the yield strength and stiffness whilst increasing the ductility of the samples. The mechanical behaviour of the structures was found to depend upon a combined effect of the type of gradient, relative density, and unit cell structure. The results showed that an increase in the relative density would enhance the specific mechanical properties. The lotus configuration displayed the highest specific mechanical properties, as its geometry reduces the stress concentrations. The numerical results showed a reasonable match with the experimental results.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"12 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-18DOI: 10.1177/14644207241236901
Lan Ngoc Nguyen, Van Quyet Truong, Dong Van Dao, May Huu Nguyen, Trung Tran
The utilization of Reclaimed Asphalt Pavement (RAP) in asphalt pavement has obtained global popularity because of its cost-efficiency, technical advantages, and positive environmental influence. However, incorporating RAP requires careful consideration of cracking resistance because of the existence of age hardening of bitumen in RAP. For the mixtures containing high RAP contents, rejuvenators are often applied to enhance the performances of aged bitumen and the cracking of mixtures. This research aims to evaluate the effects of different rejuvenators on the rheological properties of bitumen and the cracking resistance of the mixture under short and long-term aging conditions. To achieve this goal, three rejuvenators - namely, RA1 (petroleum-based), RA2 (waste vegetable oil-based), and RA3 (modified soybean oil-based) were evaluated at contents of 0%, 4%, 12%, and 20%, respectively. The dynamic shear rheometer (DSR) test results show that, under unaged and rolling thin-film oven (RTFO) aging conditions, blended bitumen with RA1 and RA3 have higher G*/sinδ than RA2. Conversely, under pressure aging vessel (PAV) aging conditions, blended bitumen with RA1 and RA3 has lower G*sinδ than that with RA2. Regarding the cracking resistance, the indirect tension asphalt cracking test results show that, under short-term oven aging (STOA) conditions, the mixture using RA2 and RA3 has a higher cracking tolerance index (CTIndex) than the one with RA1. However, under long-term oven aging (LTOA) conditions, the mixture using RA1 has the highest CTIndex value. In addition, the high correlations between G*sinδ with CTIndex and post-peak slope (|m75|) and between the CTIndex and |m75| are observed.
{"title":"Effects of rejuvenators and aging conditions on the properties of blended bitumen and the cracking behavior of hot asphalt mixtures with a high RAP content","authors":"Lan Ngoc Nguyen, Van Quyet Truong, Dong Van Dao, May Huu Nguyen, Trung Tran","doi":"10.1177/14644207241236901","DOIUrl":"https://doi.org/10.1177/14644207241236901","url":null,"abstract":"The utilization of Reclaimed Asphalt Pavement (RAP) in asphalt pavement has obtained global popularity because of its cost-efficiency, technical advantages, and positive environmental influence. However, incorporating RAP requires careful consideration of cracking resistance because of the existence of age hardening of bitumen in RAP. For the mixtures containing high RAP contents, rejuvenators are often applied to enhance the performances of aged bitumen and the cracking of mixtures. This research aims to evaluate the effects of different rejuvenators on the rheological properties of bitumen and the cracking resistance of the mixture under short and long-term aging conditions. To achieve this goal, three rejuvenators - namely, RA1 (petroleum-based), RA2 (waste vegetable oil-based), and RA3 (modified soybean oil-based) were evaluated at contents of 0%, 4%, 12%, and 20%, respectively. The dynamic shear rheometer (DSR) test results show that, under unaged and rolling thin-film oven (RTFO) aging conditions, blended bitumen with RA1 and RA3 have higher G*/sinδ than RA2. Conversely, under pressure aging vessel (PAV) aging conditions, blended bitumen with RA1 and RA3 has lower G*sinδ than that with RA2. Regarding the cracking resistance, the indirect tension asphalt cracking test results show that, under short-term oven aging (STOA) conditions, the mixture using RA2 and RA3 has a higher cracking tolerance index (CT<jats:sub>Index</jats:sub>) than the one with RA1. However, under long-term oven aging (LTOA) conditions, the mixture using RA1 has the highest CT<jats:sub>Index</jats:sub> value. In addition, the high correlations between G*sinδ with CT<jats:sub>Index</jats:sub> and post-peak slope (|m<jats:sub>75</jats:sub>|) and between the CT<jats:sub>Index</jats:sub> and |m<jats:sub>75</jats:sub>| are observed.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"60 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although conventional methods such as mechanical fastening, adhesive bonding and hot air welding have proven effective in dry conditions, they exhibit diminished efficacy in submerged environments. Hence, a thermoplastic welding technique with minimal dependence on surrounding media is essential. Ultrasonic spot welding (USW) represents a promising approach to thermoplastic joining, offering high efficiency and low operating costs. In this study, we investigate the efficacy of water-submerged ultrasonic spot welding (S-USW) for joining amorphous polyvinyl chloride (PVC) to PVC and semi-crystalline polypropylene (PP) to PP under submerged conditions. Our experimental results show that S-USW leads to a remarkable 39% and 21% increase in lap-shear strength for PVC/PVC and PP/PP welds, respectively, as compared to traditional USW techniques. We corroborate these findings with additional metrics such as Shore-D hardness tests, optical microscopy and scanning electron microscopy imagery, which collectively confirm the improved efficacy of S-USW over USW for joining PVC and PP.
{"title":"An experimental investigation on feasibility of submerged ultrasonic spot welding of thermoplastics","authors":"Sandeep Bose, Hussain Mohamed Chelladurai, Ponappa Kanaiyaram","doi":"10.1177/14644207241239475","DOIUrl":"https://doi.org/10.1177/14644207241239475","url":null,"abstract":"Although conventional methods such as mechanical fastening, adhesive bonding and hot air welding have proven effective in dry conditions, they exhibit diminished efficacy in submerged environments. Hence, a thermoplastic welding technique with minimal dependence on surrounding media is essential. Ultrasonic spot welding (USW) represents a promising approach to thermoplastic joining, offering high efficiency and low operating costs. In this study, we investigate the efficacy of water-submerged ultrasonic spot welding (S-USW) for joining amorphous polyvinyl chloride (PVC) to PVC and semi-crystalline polypropylene (PP) to PP under submerged conditions. Our experimental results show that S-USW leads to a remarkable 39% and 21% increase in lap-shear strength for PVC/PVC and PP/PP welds, respectively, as compared to traditional USW techniques. We corroborate these findings with additional metrics such as Shore-D hardness tests, optical microscopy and scanning electron microscopy imagery, which collectively confirm the improved efficacy of S-USW over USW for joining PVC and PP.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"95 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-12DOI: 10.1177/14644207241239294
M Griese, E Stammen, K Dilger
Adhesive bonding is a commonly used technology for joining dissimilar materials. However, production-related effects on the performance of the bondline have to be considered for an accurate joint design. In case of an adhesive joint in an automotive multi-material body in white, these effects arise from the so-called mismatch in thermal expansion coefficients, which leads to distortions of the adhesive in an uncured state or even damage in the cured one. The distortion of the uncured adhesive in the normal direction is called the ‘viscous fingering effect’, which reduces the adhesively bonded cross section by changing the adhesive bondline's shape to thin ‘fingers’ and therefore influences the materials properties. To investigate the effect of viscous fingering on the modulus, strength and energy release rate, linear butt bonded specimens and Tapered Double Cantilever Beams (TDCB) with different elongations of the adhesive bondline in the viscous state are investigated. The results are used to parameterize a cohesive zone model (CZM) and perform numerical analysis of the TDCB specimen for validation and to build up a model of a dissimilar joint consisting of a steel hatprofile and an adhesively bonded aluminum panel subjected to thermal distortions.
{"title":"Production-related effects on the adhesive bondline performance of structural adhesives joining dissimilar materials","authors":"M Griese, E Stammen, K Dilger","doi":"10.1177/14644207241239294","DOIUrl":"https://doi.org/10.1177/14644207241239294","url":null,"abstract":"Adhesive bonding is a commonly used technology for joining dissimilar materials. However, production-related effects on the performance of the bondline have to be considered for an accurate joint design. In case of an adhesive joint in an automotive multi-material body in white, these effects arise from the so-called mismatch in thermal expansion coefficients, which leads to distortions of the adhesive in an uncured state or even damage in the cured one. The distortion of the uncured adhesive in the normal direction is called the ‘viscous fingering effect’, which reduces the adhesively bonded cross section by changing the adhesive bondline's shape to thin ‘fingers’ and therefore influences the materials properties. To investigate the effect of viscous fingering on the modulus, strength and energy release rate, linear butt bonded specimens and Tapered Double Cantilever Beams (TDCB) with different elongations of the adhesive bondline in the viscous state are investigated. The results are used to parameterize a cohesive zone model (CZM) and perform numerical analysis of the TDCB specimen for validation and to build up a model of a dissimilar joint consisting of a steel hatprofile and an adhesively bonded aluminum panel subjected to thermal distortions.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"18 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-12DOI: 10.1177/14644207241238916
Ivan O’Neill, Aashrith Dayanand, Shane Keaveney, Kyriakos I. Kourousis
This study investigated the tensile anisotropy of steel 316L fabricated via laser powder bed fusion (L-PBF), built at different orientations. Tensile tests were performed on as-built L-PBF specimens produced at 0°, 15°, 30°, 45°, 60° and 90° angles. The yield strength, ultimate tensile strength and elasticity modulus experienced a decrease with an increasing build angle. Conversely, elongation at fracture increased as the build angle increased. The Elasticity modulus was found to be substantially lower than the nominal values reported in the material data sheet of the L-PBF equipment manufacturer. Fractography performed via Scanning Electron Microscopy (SEM) has found indications of porosity and lack of fusion that may have contributed to lower Elasticity modulus and an overall impacted mechanical performance. A complementary powder quality analysis has offered further insights on this and provided indications on the powder recycling impact.
{"title":"Tensile anisotropy of powder bed fusion steel 316L: A practical study on the effect of build orientation","authors":"Ivan O’Neill, Aashrith Dayanand, Shane Keaveney, Kyriakos I. Kourousis","doi":"10.1177/14644207241238916","DOIUrl":"https://doi.org/10.1177/14644207241238916","url":null,"abstract":"This study investigated the tensile anisotropy of steel 316L fabricated via laser powder bed fusion (L-PBF), built at different orientations. Tensile tests were performed on as-built L-PBF specimens produced at 0°, 15°, 30°, 45°, 60° and 90° angles. The yield strength, ultimate tensile strength and elasticity modulus experienced a decrease with an increasing build angle. Conversely, elongation at fracture increased as the build angle increased. The Elasticity modulus was found to be substantially lower than the nominal values reported in the material data sheet of the L-PBF equipment manufacturer. Fractography performed via Scanning Electron Microscopy (SEM) has found indications of porosity and lack of fusion that may have contributed to lower Elasticity modulus and an overall impacted mechanical performance. A complementary powder quality analysis has offered further insights on this and provided indications on the powder recycling impact.","PeriodicalId":20630,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications","volume":"8 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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