Pub Date : 2023-01-01DOI: 10.5267/j.esm.2022.12.004
Mohammadreza Malek, M. Keymanesh
Asphaltic concrete mixtures are among the most common construction materials for the pavement of roads. As a multi-phase composite mixture with randomly distributed aggregates inside the mastic part, the mechanical properties of such materials can be influenced by different factors. Cracking and induced fracture is among the common degradation and failure modes in these construction mixtures that often takes place in cold regions. In this research, the effects of some influencing parameters including temperature, air void percentage and loading rate are investigated experimentally on the fracture toughness (KIc) and work of fracture (WIc) of hot mix asphalt material. Edge notched semi-circular bend (SCB) specimen was employed to conduct mode I fracture experiments. The thickness of SCB samples were considered as variable and the HMA mixtures were tested with two SCB thicknesses of 30 and 60 mm. The experimental results showed that both fracture toughness and fracture work are increased by increasing the thickness. However, the effect of thickness on the fracture work was much more significant than the KIc value. Also, the fracture and cracking resistance parameters were increased by decreasing the temperature and air void content. Both KIc and WIc values were also increased by increasing the loading rate in the investigated range of 1 to 8 mm/min. The most influencing parameters on the change of fracture resistance parameters were the temperature, loading rate, air void content and thickness, respectively.
{"title":"Impact of thickness, void content, temperature and loading rate on tensile fracture toughness and work of fracture of asphalt mixtures- An experimental study using the SCB test","authors":"Mohammadreza Malek, M. Keymanesh","doi":"10.5267/j.esm.2022.12.004","DOIUrl":"https://doi.org/10.5267/j.esm.2022.12.004","url":null,"abstract":"Asphaltic concrete mixtures are among the most common construction materials for the pavement of roads. As a multi-phase composite mixture with randomly distributed aggregates inside the mastic part, the mechanical properties of such materials can be influenced by different factors. Cracking and induced fracture is among the common degradation and failure modes in these construction mixtures that often takes place in cold regions. In this research, the effects of some influencing parameters including temperature, air void percentage and loading rate are investigated experimentally on the fracture toughness (KIc) and work of fracture (WIc) of hot mix asphalt material. Edge notched semi-circular bend (SCB) specimen was employed to conduct mode I fracture experiments. The thickness of SCB samples were considered as variable and the HMA mixtures were tested with two SCB thicknesses of 30 and 60 mm. The experimental results showed that both fracture toughness and fracture work are increased by increasing the thickness. However, the effect of thickness on the fracture work was much more significant than the KIc value. Also, the fracture and cracking resistance parameters were increased by decreasing the temperature and air void content. Both KIc and WIc values were also increased by increasing the loading rate in the investigated range of 1 to 8 mm/min. The most influencing parameters on the change of fracture resistance parameters were the temperature, loading rate, air void content and thickness, respectively.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70760574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2022.8.002
S. Nurjannah, S. Saloma, Yulindasari Yulindasari, K. Aminuddin, Gilbert Chuhairy
Reinforced concrete wall critical zones are the responsive areas of dissipated earthquake loads. They are formed in the connection of the wall panels and the fixed restraints. The longitudinal and transversal steel reinforcements with certain spacing are designed according to the required nominal strength at the connections. Under certain conditions, the reinforcement distance becomes very tight, making working on castings using normal concrete difficult. This condition also occurs in boundary elements consisting of longitudinal and transversal reinforcements in tight spaces. A concrete material that flows easily and solidifies itself is required to avoid segregation. One type of this material is Self-Compacting Concrete (SCC). The SCC performance as a wall panel material that withstands gravity and cyclic lateral loads still require further research. This study aimed to analyze the hysteretic performance of reinforced SCC wall panels with variations of shear reinforcement in resisting cyclic lateral loads. The analysis used software based on numerical analysis. The drift ratios, hysteretic curves, stress patterns, ductility, and stiffness of the wall panels were analyzed. The SCC wall panel with ordinary shear reinforcement resisted lateral positive and negative loads of 152.32 kN and 143.09 kN, respectively. In comparison, the wall panel with boundary elements and tighter shear reinforcements could withstand the positive and negative lateral loads of 187.62 kN and 145.98 kN, respectively. The SCC wall panel reached the best ductility of 21.38 with ordinary shear reinforcement because the yield occurred faster than in other wall panels. The results showed that the boundary elements and shear reinforcements of reinforced SCC wall panels affected the performance in resisting cyclic lateral loads.
{"title":"The analysis of numerical self-compacting concrete wall panel models with variations of shear reinforcement","authors":"S. Nurjannah, S. Saloma, Yulindasari Yulindasari, K. Aminuddin, Gilbert Chuhairy","doi":"10.5267/j.esm.2022.8.002","DOIUrl":"https://doi.org/10.5267/j.esm.2022.8.002","url":null,"abstract":"Reinforced concrete wall critical zones are the responsive areas of dissipated earthquake loads. They are formed in the connection of the wall panels and the fixed restraints. The longitudinal and transversal steel reinforcements with certain spacing are designed according to the required nominal strength at the connections. Under certain conditions, the reinforcement distance becomes very tight, making working on castings using normal concrete difficult. This condition also occurs in boundary elements consisting of longitudinal and transversal reinforcements in tight spaces. A concrete material that flows easily and solidifies itself is required to avoid segregation. One type of this material is Self-Compacting Concrete (SCC). The SCC performance as a wall panel material that withstands gravity and cyclic lateral loads still require further research. This study aimed to analyze the hysteretic performance of reinforced SCC wall panels with variations of shear reinforcement in resisting cyclic lateral loads. The analysis used software based on numerical analysis. The drift ratios, hysteretic curves, stress patterns, ductility, and stiffness of the wall panels were analyzed. The SCC wall panel with ordinary shear reinforcement resisted lateral positive and negative loads of 152.32 kN and 143.09 kN, respectively. In comparison, the wall panel with boundary elements and tighter shear reinforcements could withstand the positive and negative lateral loads of 187.62 kN and 145.98 kN, respectively. The SCC wall panel reached the best ductility of 21.38 with ordinary shear reinforcement because the yield occurred faster than in other wall panels. The results showed that the boundary elements and shear reinforcements of reinforced SCC wall panels affected the performance in resisting cyclic lateral loads.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70760987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2022.8.001
Shikha Parashar, V. Chawla
The increasing demand for good and improved polymeric composites has led to a surge in the number of researches on hybrid composites, strengthened and enforced with the natural fibres. This paper mainly analyses and presents the attributes of hybrid composites made from natural fibres and carbon nano-tube (CNT) nanoparticles. A novel hybrid composite considered in this research includes kenaf and coir fibres with CNT nanoparticles embedded in an epoxy matrix. The proposed hybrid nanocomposite’s elastic features are calculated by using different analytical models like Chamis, Mori-Tanaka, Nielson elastic models etc and also with the help of Representative Volume Element Analysis (RVE). The content of fibre volume is varied in four different samples and it is found that upon varying the content of fibre volume, the mechanical properties like longitudinal modulus and transverse modulus got affected. The results evaluated from different analytical models are observed to be in good agreement with each other and also with the results of RVE analysis.
对优质和改进的聚合物复合材料的需求日益增长，导致混合复合材料的研究数量激增，与天然纤维加强和强化。本文主要分析和介绍了天然纤维与纳米碳管复合材料的特性。在这项研究中考虑了一种新型的混杂复合材料，包括红麻和椰子纤维与碳纳米管纳米颗粒嵌入环氧基体。采用Chamis、Mori-Tanaka、Nielson弹性模型等不同的分析模型，并借助于代表性体积元分析(Representative Volume Element Analysis, RVE)，计算了复合材料的弹性特性。通过对四种不同试样纤维体积含量的变化，发现纤维体积含量的变化会影响试件的纵向模量和横向模量等力学性能。不同分析模型的计算结果与RVE分析结果基本一致。
{"title":"Kenaf-Coir based hybrid nano-composite: an analytical and representative volume element analysis","authors":"Shikha Parashar, V. Chawla","doi":"10.5267/j.esm.2022.8.001","DOIUrl":"https://doi.org/10.5267/j.esm.2022.8.001","url":null,"abstract":"The increasing demand for good and improved polymeric composites has led to a surge in the number of researches on hybrid composites, strengthened and enforced with the natural fibres. This paper mainly analyses and presents the attributes of hybrid composites made from natural fibres and carbon nano-tube (CNT) nanoparticles. A novel hybrid composite considered in this research includes kenaf and coir fibres with CNT nanoparticles embedded in an epoxy matrix. The proposed hybrid nanocomposite’s elastic features are calculated by using different analytical models like Chamis, Mori-Tanaka, Nielson elastic models etc and also with the help of Representative Volume Element Analysis (RVE). The content of fibre volume is varied in four different samples and it is found that upon varying the content of fibre volume, the mechanical properties like longitudinal modulus and transverse modulus got affected. The results evaluated from different analytical models are observed to be in good agreement with each other and also with the results of RVE analysis.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2023.1.004
N. T. Tung, L. V. Van
This paper presents the results of research on the vibration of the Hyundai Universe bus using an air suspension system and mechanical suspension system when it is run at different speeds on random road surface profiles according to ISO 8608:2016. The research results show that the used air suspension system ensures smooth movement and dynamic safety according to TCVN 6964:2008 (ISO 2631:2003) and VDI 2057:2017 standards. The maximum vehicle speeds on different road classes varied from 105km/h to 65km/h. A vehicle with an air suspension system provided a smaller root mean square of vibration acceleration RMS(Z) than a vehicle with a mechanical suspension system. The root means square of the wheel load RMS(Fz) of a vehicle with an air suspension system is about 99.6% of that of a vehicle with a mechanical suspension system.
本文根据ISO 8608:2016标准，对现代宇宙客车使用空气悬架系统和机械悬架系统在随机路面上以不同速度行驶时的振动进行了研究。研究结果表明，所使用的空气悬架系统确保了TCVN 6964:2008 (ISO 2631:2003)和VDI 2057:2017标准的平稳运行和动态安全。不同道路等级的最高车速从105公里/小时到65公里/小时不等。采用空气悬架系统的车辆的振动加速度均方根RMS(Z)比采用机械悬架系统的车辆要小。采用空气悬架的车辆的轮载RMS(Fz)的均方根约为采用机械悬架的车辆的99.6%。
{"title":"A study on the vibration of a bus with air suspension system moving on random road surface profiles with different speeds","authors":"N. T. Tung, L. V. Van","doi":"10.5267/j.esm.2023.1.004","DOIUrl":"https://doi.org/10.5267/j.esm.2023.1.004","url":null,"abstract":"This paper presents the results of research on the vibration of the Hyundai Universe bus using an air suspension system and mechanical suspension system when it is run at different speeds on random road surface profiles according to ISO 8608:2016. The research results show that the used air suspension system ensures smooth movement and dynamic safety according to TCVN 6964:2008 (ISO 2631:2003) and VDI 2057:2017 standards. The maximum vehicle speeds on different road classes varied from 105km/h to 65km/h. A vehicle with an air suspension system provided a smaller root mean square of vibration acceleration RMS(Z) than a vehicle with a mechanical suspension system. The root means square of the wheel load RMS(Fz) of a vehicle with an air suspension system is about 99.6% of that of a vehicle with a mechanical suspension system.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2023.4.002
I. Erunkulu, G. Malumbela, O. Oladijo
The effect of the chemical composition of geopolymer pastes on compressive strength was investigated in high-calcium fly ash and copper slag blends. In synthesizing the pastes, soda ash at activator to binder ratio of 0.4 was used. The characterization of material samples and the hardened fly ash-copper slag pastes was conducted through X-ray fluorescence (XRF), and X-ray diffraction (XRD) for the major oxide and phase composition. The hardened paste cubes which were cured at 80 °C were tested for compressive strength at ages 3, 7, and 28 days to obtain the mechanical performance property of each respective mix. The findings establish the impact of variation in the individual material and paste composition on the compressive strength of fly ash-copper slag geopolymer. The result shows that increase in the SiO2/Al2O3 and Na2O/Al2O3 ratios of paste products of samples corresponded to an increase in compressive strength. Whilst Fe2O3 wt.% increase in products from slag addition and positively influenced the compressive strength as fillers. However, CaO had no positive influence on the matrix of the activated product. The optimal blend mix design was 40 wt.% of copper slag which achieved a 28-day compressive strength of 24.66 MPa.
{"title":"Influence of chemical composition of soda ash activated fly ash and copper slag geopolymer pastes on compressive strength","authors":"I. Erunkulu, G. Malumbela, O. Oladijo","doi":"10.5267/j.esm.2023.4.002","DOIUrl":"https://doi.org/10.5267/j.esm.2023.4.002","url":null,"abstract":"The effect of the chemical composition of geopolymer pastes on compressive strength was investigated in high-calcium fly ash and copper slag blends. In synthesizing the pastes, soda ash at activator to binder ratio of 0.4 was used. The characterization of material samples and the hardened fly ash-copper slag pastes was conducted through X-ray fluorescence (XRF), and X-ray diffraction (XRD) for the major oxide and phase composition. The hardened paste cubes which were cured at 80 °C were tested for compressive strength at ages 3, 7, and 28 days to obtain the mechanical performance property of each respective mix. The findings establish the impact of variation in the individual material and paste composition on the compressive strength of fly ash-copper slag geopolymer. The result shows that increase in the SiO2/Al2O3 and Na2O/Al2O3 ratios of paste products of samples corresponded to an increase in compressive strength. Whilst Fe2O3 wt.% increase in products from slag addition and positively influenced the compressive strength as fillers. However, CaO had no positive influence on the matrix of the activated product. The optimal blend mix design was 40 wt.% of copper slag which achieved a 28-day compressive strength of 24.66 MPa.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2023.3.001
M. J. Srujan, S. Srikanth
Glass Fiber Reinforced Polymer (GFRP) is a polymer composite material used in lightweight structures. This study provides insight into achieving robust GFRP H-section short-column spliced connections using bonded, bolted, and hybrid connections. The design specifications for steel splicing connections are based on BS EN 1990 and BS EN 1991 guidelines. Based on the samples subjected to axial loading, factors such as compressive strength, bonding and bearing resistance, compression behavior of the connection, and failure modes of the structure are investigated. The study includes the behavioral characteristics and results of 25 GFRP H-section Spliced connections, with each H-section measuring 152 x 72 x 6.4 mm and standing 350 mm in height. This study also examines the behavior of a composite splice joint made up of steel cover plates and steel bolts that are used to create an ideal non-bearing spliced connection. This model is used to compare to the other models to understand the behavior of spliced joints designed with GFRP cover plates. This paper holds design specifications of connections that have displayed compressive strengths of 82.35 %, 89.82 %, and 92.83 % compared to that of an un-cut GFRP H-section subjected to axial loading.
玻璃纤维增强聚合物(GFRP)是一种用于轻量化结构的高分子复合材料。本研究提供了通过粘合、螺栓连接和混合连接实现坚固的GFRP h截面短柱拼接连接的见解。钢连接的设计规范基于BS en1990和BS en1991指南。在轴向加载的基础上，研究了结构的抗压强度、粘结和承载阻力、连接的压缩性能和破坏模式等因素。该研究包括25个玻璃钢h型钢拼接连接的行为特征和结果，每个h型钢的尺寸为152 x 72 x 6.4 mm，高度为350 mm。本研究还研究了由钢盖板和钢螺栓组成的复合拼接接头的性能，该接头用于创建理想的无轴承拼接连接。该模型用于与其他模型进行比较，以了解GFRP盖板设计的拼接节点的性能。本文给出了连接的设计规范，与未切割的玻璃钢h型截面相比，其抗压强度分别为82.35%、89.82%和92.83%。
{"title":"Experimental analysis of bolted, bonded, and hybrid spliced joint connections in glass fiber reinforced polymer short column","authors":"M. J. Srujan, S. Srikanth","doi":"10.5267/j.esm.2023.3.001","DOIUrl":"https://doi.org/10.5267/j.esm.2023.3.001","url":null,"abstract":"Glass Fiber Reinforced Polymer (GFRP) is a polymer composite material used in lightweight structures. This study provides insight into achieving robust GFRP H-section short-column spliced connections using bonded, bolted, and hybrid connections. The design specifications for steel splicing connections are based on BS EN 1990 and BS EN 1991 guidelines. Based on the samples subjected to axial loading, factors such as compressive strength, bonding and bearing resistance, compression behavior of the connection, and failure modes of the structure are investigated. The study includes the behavioral characteristics and results of 25 GFRP H-section Spliced connections, with each H-section measuring 152 x 72 x 6.4 mm and standing 350 mm in height. This study also examines the behavior of a composite splice joint made up of steel cover plates and steel bolts that are used to create an ideal non-bearing spliced connection. This model is used to compare to the other models to understand the behavior of spliced joints designed with GFRP cover plates. This paper holds design specifications of connections that have displayed compressive strengths of 82.35 %, 89.82 %, and 92.83 % compared to that of an un-cut GFRP H-section subjected to axial loading.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2023.5.005
Fahim Faisal Arnob, Md Sayed Anwar, M. Islam, M. Arifuzzaman, Md Abdullah Al Bari
The leaf spring is one of the main components in an automobile which carries the weight of the vehicle and passenger as well as absorbs the vibration and shock produced due to road irregularities. The weight, natural frequency, stress developed, energy absorption, fatigue life, etc. are the key factors that need to be considered to design a leaf spring. Towards that, a novel design integrating a Negative Stiffness Honeycomb Structure (NSHS) in the leaf spring is proposed. The proposed design and the traditional leaf spring are analyzed using the commercially available Finite Element Method (FEM) software Abaqus. Both the traditional and NSHS models were created using Solidworks and modal, harmonic, structural, and transient analyses were performed. It is found that the natural frequency of the NSHS leaf spring is well above the frequency produced due to road irregularities although it is lower than the traditional spring. The total weight of the NSHS spring structure is reduced significantly by 30.73% compared to the traditional spring. Structural analysis shows a lower stress development and higher energy absorption capacity for the NSHS leaf spring. Transient analysis reveals lower mean stress in the proposed NSHS spring. The fatigue life is also found to be 82.78 % higher in the proposed design. The NSHS-incorporated novel leaf spring design may be an excellent alternative to the traditional leaf spring.
{"title":"Negative stiffness honeycomb structure as automobile leaf spring: A numerical investigation","authors":"Fahim Faisal Arnob, Md Sayed Anwar, M. Islam, M. Arifuzzaman, Md Abdullah Al Bari","doi":"10.5267/j.esm.2023.5.005","DOIUrl":"https://doi.org/10.5267/j.esm.2023.5.005","url":null,"abstract":"The leaf spring is one of the main components in an automobile which carries the weight of the vehicle and passenger as well as absorbs the vibration and shock produced due to road irregularities. The weight, natural frequency, stress developed, energy absorption, fatigue life, etc. are the key factors that need to be considered to design a leaf spring. Towards that, a novel design integrating a Negative Stiffness Honeycomb Structure (NSHS) in the leaf spring is proposed. The proposed design and the traditional leaf spring are analyzed using the commercially available Finite Element Method (FEM) software Abaqus. Both the traditional and NSHS models were created using Solidworks and modal, harmonic, structural, and transient analyses were performed. It is found that the natural frequency of the NSHS leaf spring is well above the frequency produced due to road irregularities although it is lower than the traditional spring. The total weight of the NSHS spring structure is reduced significantly by 30.73% compared to the traditional spring. Structural analysis shows a lower stress development and higher energy absorption capacity for the NSHS leaf spring. Transient analysis reveals lower mean stress in the proposed NSHS spring. The fatigue life is also found to be 82.78 % higher in the proposed design. The NSHS-incorporated novel leaf spring design may be an excellent alternative to the traditional leaf spring.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2023.5.009
A. Imran, M. Haghjoo, B. Beigzadeh
The push-off phase is a critical part of initiating movement during walking, and it requires a significant amount of energy. Recent research has shown that the passive use of springs in parallel with the leg can harvest the push-off energy and reduce the total metabolic energy of walking for healthy subjects. In this study, we present the design of a prosthetic leg with a passive-based mechanism to reduce walking energy consumption for above-knee amputees. The mechanism stores energy during the stance phase of the gait cycle and releases it to support the prosthetic leg during locomotion. The known polycentric knee joint 3R36 and the ankle-foot joint ESAR were chosen and adopted for this study. We also utilized a ratchet clutch that connects with a spring and rope from the pylon to the foot which regulates movement and saves energy. Our simulations demonstrate that the spring stores elastic energy from approximately 22% of the gait cycle and reaches its maximum energy storage at approximately 50% of the walking cycle. The energy is then released at approximately 58% of the stride cycle during the push-off phase. The motion of the proposed prosthetic leg for individuals with transfemoral amputations mimics the normal walking pattern of healthy individuals well.
{"title":"Design of a novel above-knee prosthetic leg with a passive energy-saving mechanism","authors":"A. Imran, M. Haghjoo, B. Beigzadeh","doi":"10.5267/j.esm.2023.5.009","DOIUrl":"https://doi.org/10.5267/j.esm.2023.5.009","url":null,"abstract":"The push-off phase is a critical part of initiating movement during walking, and it requires a significant amount of energy. Recent research has shown that the passive use of springs in parallel with the leg can harvest the push-off energy and reduce the total metabolic energy of walking for healthy subjects. In this study, we present the design of a prosthetic leg with a passive-based mechanism to reduce walking energy consumption for above-knee amputees. The mechanism stores energy during the stance phase of the gait cycle and releases it to support the prosthetic leg during locomotion. The known polycentric knee joint 3R36 and the ankle-foot joint ESAR were chosen and adopted for this study. We also utilized a ratchet clutch that connects with a spring and rope from the pylon to the foot which regulates movement and saves energy. Our simulations demonstrate that the spring stores elastic energy from approximately 22% of the gait cycle and reaches its maximum energy storage at approximately 50% of the walking cycle. The energy is then released at approximately 58% of the stride cycle during the push-off phase. The motion of the proposed prosthetic leg for individuals with transfemoral amputations mimics the normal walking pattern of healthy individuals well.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70762345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2022.9.002
Z. Ashkeyev, Maxat Abishkenov, K. Nogaev
The article presents an analysis of the stress state of workpieces during upsetting of workpieces with an additional shear. For the analysis, the slip line method and the finite element method were used. A schematic diagram of upsetting in dies with “floating” elements, contributing to the implementation of additional shear, reduction of barreling, inhomogenous deformation and contour tensile stresses, is presented. The analysis of the research results showed that during upsetting of workpieces with additional shift forces, tensile stresses on the side surface of the workpieces decrease, which excludes the appearance of cracks on the side surface of the samples, especially when processing low-plastic alloy steels and alloys, and also reduces the barreling of the side surface.
{"title":"Stress state of workpieces during upsetting with additional shear","authors":"Z. Ashkeyev, Maxat Abishkenov, K. Nogaev","doi":"10.5267/j.esm.2022.9.002","DOIUrl":"https://doi.org/10.5267/j.esm.2022.9.002","url":null,"abstract":"The article presents an analysis of the stress state of workpieces during upsetting of workpieces with an additional shear. For the analysis, the slip line method and the finite element method were used. A schematic diagram of upsetting in dies with “floating” elements, contributing to the implementation of additional shear, reduction of barreling, inhomogenous deformation and contour tensile stresses, is presented. The analysis of the research results showed that during upsetting of workpieces with additional shift forces, tensile stresses on the side surface of the workpieces decrease, which excludes the appearance of cracks on the side surface of the samples, especially when processing low-plastic alloy steels and alloys, and also reduces the barreling of the side surface.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.5267/j.esm.2023.1.003
M. S. Mohsenzadeh
In this study, the influence of the volume fraction of the martensite phase as well as the size of the martensite particles on the mechanism of particle fracture in dual-phase steel were examined. A combined continuum/dislocation based approach was used in order to model the average stress in the martensite particles. It was found that the model predictions are in accordance with the experimental results. For the same volume fraction of the martensite particles, the model predicts an increase of the internal stress and the average stress in the martensite particles with increasing the particles size. Since the fracture strength of the martensite depends on its volume fraction, the particle size has no effect on the mechanism of particle fracture. Increasing the volume fraction of the martensite particles results in the enhancement of the internal stress in the martensite particles. However, it has a slight influence on the average stress in the particles. Nevertheless, because of decreasing the fracture strength of martensite with increasing its volume fraction, this parameter has a main role in the occurrence of the particle fracture mechanism.
{"title":"A micromechanical study on the correlation of the microstructure and failure mechanism of dual-phase steels under tension","authors":"M. S. Mohsenzadeh","doi":"10.5267/j.esm.2023.1.003","DOIUrl":"https://doi.org/10.5267/j.esm.2023.1.003","url":null,"abstract":"In this study, the influence of the volume fraction of the martensite phase as well as the size of the martensite particles on the mechanism of particle fracture in dual-phase steel were examined. A combined continuum/dislocation based approach was used in order to model the average stress in the martensite particles. It was found that the model predictions are in accordance with the experimental results. For the same volume fraction of the martensite particles, the model predicts an increase of the internal stress and the average stress in the martensite particles with increasing the particles size. Since the fracture strength of the martensite depends on its volume fraction, the particle size has no effect on the mechanism of particle fracture. Increasing the volume fraction of the martensite particles results in the enhancement of the internal stress in the martensite particles. However, it has a slight influence on the average stress in the particles. Nevertheless, because of decreasing the fracture strength of martensite with increasing its volume fraction, this parameter has a main role in the occurrence of the particle fracture mechanism.","PeriodicalId":37952,"journal":{"name":"Engineering Solid Mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70761428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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