A large-scale recycling and reuse application of scrap shingles would utilize an otherwise wasted resource while clearing landfill space and creating new business opportunities. One potential reuse application is the use of reclaimed asphalt shingles (RAS) as an additive or substitute for the earth materials typically used in the aggregate base (AB) and subbase (ASB) layers of roadway pavements. The purpose of this study was to determine the technical specifications of RAS, the effect of fly ash stabilization on RAS strength, and the practicality of the widespread implementation of RAS in the AB and ASB layers of roadway pavements. RAS, fly ash stabilized RAS (S-RAS), RAS-aggregate mixtures, and RAS-silt mixtures were evaluated for particle size characteristics, compaction characteristics, CA Bearing Ratio (CBR), unconfined compressive strength, and resilient modulus. According to the results of the testing protocol, unstabilized RAS is unsuitable as base material although RAS could potentially be used as subbase or general fill material. RAS-aggregate mixtures are suitable for use as subbase and are potentially suitable as base course in an unstabilized state; however, RAS-aggregate mixtures exhibited decreasing resilient modulus with increasing RAS content. Fly ash stabilized RAS (S-RAS) was less susceptible to penetrative deformation than unstabilized RAS, however, S-RAS was still highly susceptible to penetrative deformation when unpaved. Fly ash stabilization of RAS generally provided less improvement in resilient modulus compared to fly ash stabilized low-plasticity clays. This may be due to the high asphalt content of RAS particles and resulting diminishment in pozzolanic activity and/or the diminished particle interconnectedness for cementation. Other forms of stabilization, such as cold asphalt emulsion, may be more effective in strengthening RAS. Further evaluation of alternative stabilization methods and additional studies to evaluate the practicality of RAS in other geotechnical applications such as embankment fill, filter, and/or drainage material are recommended.
{"title":"An Evaluation of Reclaimed Asphalt Shingles for Beneficial Reuse in Roadway Construction","authors":"J. Warner, T. Edil, S. Dean","doi":"10.1520/JAI103665","DOIUrl":"https://doi.org/10.1520/JAI103665","url":null,"abstract":"A large-scale recycling and reuse application of scrap shingles would utilize an otherwise wasted resource while clearing landfill space and creating new business opportunities. One potential reuse application is the use of reclaimed asphalt shingles (RAS) as an additive or substitute for the earth materials typically used in the aggregate base (AB) and subbase (ASB) layers of roadway pavements. The purpose of this study was to determine the technical specifications of RAS, the effect of fly ash stabilization on RAS strength, and the practicality of the widespread implementation of RAS in the AB and ASB layers of roadway pavements. RAS, fly ash stabilized RAS (S-RAS), RAS-aggregate mixtures, and RAS-silt mixtures were evaluated for particle size characteristics, compaction characteristics, CA Bearing Ratio (CBR), unconfined compressive strength, and resilient modulus. According to the results of the testing protocol, unstabilized RAS is unsuitable as base material although RAS could potentially be used as subbase or general fill material. RAS-aggregate mixtures are suitable for use as subbase and are potentially suitable as base course in an unstabilized state; however, RAS-aggregate mixtures exhibited decreasing resilient modulus with increasing RAS content. Fly ash stabilized RAS (S-RAS) was less susceptible to penetrative deformation than unstabilized RAS, however, S-RAS was still highly susceptible to penetrative deformation when unpaved. Fly ash stabilization of RAS generally provided less improvement in resilient modulus compared to fly ash stabilized low-plasticity clays. This may be due to the high asphalt content of RAS particles and resulting diminishment in pozzolanic activity and/or the diminished particle interconnectedness for cementation. Other forms of stabilization, such as cold asphalt emulsion, may be more effective in strengthening RAS. Further evaluation of alternative stabilization methods and additional studies to evaluate the practicality of RAS in other geotechnical applications such as embankment fill, filter, and/or drainage material are recommended.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90293322","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}
B. S. Adair, W. S. Johnson, S. Antolovich, A. Staroselsky
A study was conducted to explore some of the load and temperature interaction effects on the fatigue crack growth rate (FCGR) of polycrystalline superalloy IN100. Load interaction testing in the form of single overloads was performed at 316°C and 649°C. Temperature interaction testing was performed by cycling between 316°C and 649°C in blocks of 1, 10, and 100 cycles. After compiling a database of constant temperature, constant amplitude FCGR for IN100, fatigue crack growth predictions assuming no load or temperature interactions were made. Experimental fatigue crack propagation data were then compared with these predictions to assess interaction effects. The fracture mechanisms observed during interaction testing using a scanning electron microscope were compared with the mechanisms present during constant temperature, constant amplitude testing. Overload interaction testing led to full crack retardation at 2.0 × overloads for both 316°C and 649°C testing. Overloading by 1.6 × at both temperatures led to retarded crack growth, whereas 1.3 × overloads at 649°C created accelerated crack growth and at 316°C the crack growth was retarded. One block alternating temperature interaction testing grew significantly faster than the non-interaction prediction, while 10 block alternating temperature interaction testing also grew faster but not to the same extent. One hundred block alternating testing grew slower than non-interaction predictions. Possible explanations for the interaction effects responsible for the observed crack growth acceleration and retardation are discussed.
{"title":"Temperature and Load Interaction Effects on the Fatigue Crack Growth Rate and Fracture Surface Morphology of IN100 Superalloy","authors":"B. S. Adair, W. S. Johnson, S. Antolovich, A. Staroselsky","doi":"10.1520/JAI104215","DOIUrl":"https://doi.org/10.1520/JAI104215","url":null,"abstract":"A study was conducted to explore some of the load and temperature interaction effects on the fatigue crack growth rate (FCGR) of polycrystalline superalloy IN100. Load interaction testing in the form of single overloads was performed at 316°C and 649°C. Temperature interaction testing was performed by cycling between 316°C and 649°C in blocks of 1, 10, and 100 cycles. After compiling a database of constant temperature, constant amplitude FCGR for IN100, fatigue crack growth predictions assuming no load or temperature interactions were made. Experimental fatigue crack propagation data were then compared with these predictions to assess interaction effects. The fracture mechanisms observed during interaction testing using a scanning electron microscope were compared with the mechanisms present during constant temperature, constant amplitude testing. Overload interaction testing led to full crack retardation at 2.0 × overloads for both 316°C and 649°C testing. Overloading by 1.6 × at both temperatures led to retarded crack growth, whereas 1.3 × overloads at 649°C created accelerated crack growth and at 316°C the crack growth was retarded. One block alternating temperature interaction testing grew significantly faster than the non-interaction prediction, while 10 block alternating temperature interaction testing also grew faster but not to the same extent. One hundred block alternating testing grew slower than non-interaction predictions. Possible explanations for the interaction effects responsible for the observed crack growth acceleration and retardation are discussed.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85723879","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}
Reinforced polymeric piling (RPP) is a sustainable piling product that is gaining attention for use instead of timber piling in coastal and waterfront applications. However, unlike conventional construction materials that have well-documented creep behavior, there is virtually no reliable data on the compressive creep behavior of RPP. RPP is composed of a recycled plastic matrix made of high density polyethylene (HDPE) that is reinforced with steel or fiber reinforced polymer rods (FRP, E-glass, or fiberglass). In this study, an accelerated test method to predict the compressive creep of both recycled HDPE and FRP is employed. The method is based on the equivalence of strain energy density (SED) between conventional constant-stress creep tests and stress-strain tests, conducted at different strain rates. Test results indicate that the tested recycled HDPE exhibited a pronounced viscoelastic or viscoplastic response, at low strains, when loaded in compression. At room temperature, SED predicts that recycled HDPE will creep about 1.1 % in 100 years when loaded at an ultimate stress of 8.3 MPa (1200 psi). FRP exhibits a small viscoelastic tendency. SED predicts that the FRP loaded in compression will creep by less than 0.5 % in 100 years when loaded at an ultimate stress of 88 MPa (12 800 psi). The stress-strain behavior of RPP depends on strain compatibility of both HDPE and FRP. Creep of RPP will depend on the percentage of FRP reinforcement in the cross section. Creep of RPP is estimated to be on the order of 0.2 % to 1.8 % in 100 years under loading and reinforcement ratios employed for this research.
{"title":"Compressive creep of reinforced polymeric piling","authors":"Amir Bozorg-Haddad, Magued Iskander","doi":"10.1520/JAI103668","DOIUrl":"https://doi.org/10.1520/JAI103668","url":null,"abstract":"Reinforced polymeric piling (RPP) is a sustainable piling product that is gaining attention for use instead of timber piling in coastal and waterfront applications. However, unlike conventional construction materials that have well-documented creep behavior, there is virtually no reliable data on the compressive creep behavior of RPP. RPP is composed of a recycled plastic matrix made of high density polyethylene (HDPE) that is reinforced with steel or fiber reinforced polymer rods (FRP, E-glass, or fiberglass). In this study, an accelerated test method to predict the compressive creep of both recycled HDPE and FRP is employed. The method is based on the equivalence of strain energy density (SED) between conventional constant-stress creep tests and stress-strain tests, conducted at different strain rates. Test results indicate that the tested recycled HDPE exhibited a pronounced viscoelastic or viscoplastic response, at low strains, when loaded in compression. At room temperature, SED predicts that recycled HDPE will creep about 1.1 % in 100 years when loaded at an ultimate stress of 8.3 MPa (1200 psi). FRP exhibits a small viscoelastic tendency. SED predicts that the FRP loaded in compression will creep by less than 0.5 % in 100 years when loaded at an ultimate stress of 88 MPa (12 800 psi). The stress-strain behavior of RPP depends on strain compatibility of both HDPE and FRP. Creep of RPP will depend on the percentage of FRP reinforcement in the cross section. Creep of RPP is estimated to be on the order of 0.2 % to 1.8 % in 100 years under loading and reinforcement ratios employed for this research.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90791360","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}
K. Senetakis, A. Anastasiadis, K. Pitilakis, A. Souli
This paper examines the strain-dependent dynamic properties (G/GO-logγ-DT curves) of dry and saturated sand–recycled rubber mixtures in a range of shearing strain amplitudes from (5 × 10−4) % to (6 × 10−1) % using a fixed-free torsional resonant column device. The effect of the rubber content on the pore water pressure buildup and volumetric threshold strain γtv of saturated mixtures, as well as the effect of specimens’ geometry on the experimental data, are also presented and discussed. Based on a comprehensive set of experimental results, a modified hyperbolic model, frequently used in practice, has been proposed. An increase in the rubber content leads to a more linear shape of the G/GO-logγ and DT-logγ curves and a reduction in the pore water pressure buildup. Damping is expressed in terms of DT-DTO, which eliminates the effect of the rubber content and the mean confining pressure. The final aim is to propose appropriate design G/GO-logγ-DT curves for sand–rubber mixtures currently used in practice.
{"title":"Dynamic Behavior of Sand/Rubber Mixtures, Part II: Effect of Rubber Content on G/G O -γ-DT Curves and Volumetric Threshold Strain","authors":"K. Senetakis, A. Anastasiadis, K. Pitilakis, A. Souli","doi":"10.1520/JAI103711","DOIUrl":"https://doi.org/10.1520/JAI103711","url":null,"abstract":"This paper examines the strain-dependent dynamic properties (G/GO-logγ-DT curves) of dry and saturated sand–recycled rubber mixtures in a range of shearing strain amplitudes from (5 × 10−4) % to (6 × 10−1) % using a fixed-free torsional resonant column device. The effect of the rubber content on the pore water pressure buildup and volumetric threshold strain γtv of saturated mixtures, as well as the effect of specimens’ geometry on the experimental data, are also presented and discussed. Based on a comprehensive set of experimental results, a modified hyperbolic model, frequently used in practice, has been proposed. An increase in the rubber content leads to a more linear shape of the G/GO-logγ and DT-logγ curves and a reduction in the pore water pressure buildup. Damping is expressed in terms of DT-DTO, which eliminates the effect of the rubber content and the mean confining pressure. The final aim is to propose appropriate design G/GO-logγ-DT curves for sand–rubber mixtures currently used in practice.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91442783","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}
The Ringhals site is situated on the Swedish southwest coastline. At the site, there are four operating nuclear power plants. Historically, the Swedish policy has been that the nuclear power plants were to be closed in 2010. The present position is to operate the units until their technical and economic lifetime has run out. The units shall be maintained and invested in to ensure a lifetime of at least 50 years, but the actions taken shall not limit the time to this date. When the initial surveillance capsules were evaluated, it was noted that the material properties of the weld material of unit 3 and 4 showed some deviations from the expected behaviour. Currently there is an extensive project running for re-evaluating the embrittlement situation from a long-term operating perspective. One part of the project is aimed at more accurately determining the fluence levels of the reactor pressure vessels (RPVs). The basis for the early evaluations of the dosimeters in the surveillance capsules and the corresponding fluence evaluation had an operating lifetime of 25 years as a target value. Therefore, the accuracy and refinement of the measurement and calculation were taken to be good enough to suit this life span. Looking back at the results from the dosimetry measurements there are a few discrepancies. Some of the dosimeters were disintegrated and some measurements had comparatively large uncertainties. When starting this project there were some re-evaluations done with the old fluence prediction model. For every new run and refinement there appeared new difficulties, and the decision was to start the evaluation from scratch. Then there are two questions remaining regarding the fluence: What is the current fluence level? What will the resulting fluence be after 60 years of operation, when we have up-rated output power of both reactors? This paper aims to describe the view of the fluence evaluation in the surveillance program of the RPV, both in a historical and prospective view.
{"title":"Ringhals Unit 3 and 4—Fluence Determination in a Historic and Future Perspective","authors":"E. Green, J. Roudén, P. Efsing","doi":"10.1520/JAI104012","DOIUrl":"https://doi.org/10.1520/JAI104012","url":null,"abstract":"The Ringhals site is situated on the Swedish southwest coastline. At the site, there are four operating nuclear power plants. Historically, the Swedish policy has been that the nuclear power plants were to be closed in 2010. The present position is to operate the units until their technical and economic lifetime has run out. The units shall be maintained and invested in to ensure a lifetime of at least 50 years, but the actions taken shall not limit the time to this date. When the initial surveillance capsules were evaluated, it was noted that the material properties of the weld material of unit 3 and 4 showed some deviations from the expected behaviour. Currently there is an extensive project running for re-evaluating the embrittlement situation from a long-term operating perspective. One part of the project is aimed at more accurately determining the fluence levels of the reactor pressure vessels (RPVs). The basis for the early evaluations of the dosimeters in the surveillance capsules and the corresponding fluence evaluation had an operating lifetime of 25 years as a target value. Therefore, the accuracy and refinement of the measurement and calculation were taken to be good enough to suit this life span. Looking back at the results from the dosimetry measurements there are a few discrepancies. Some of the dosimeters were disintegrated and some measurements had comparatively large uncertainties. When starting this project there were some re-evaluations done with the old fluence prediction model. For every new run and refinement there appeared new difficulties, and the decision was to start the evaluation from scratch. Then there are two questions remaining regarding the fluence: What is the current fluence level? What will the resulting fluence be after 60 years of operation, when we have up-rated output power of both reactors? This paper aims to describe the view of the fluence evaluation in the surveillance program of the RPV, both in a historical and prospective view.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76386087","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}
Nitro-oxidized steel specimens welded by a CO2 laser and an electron beam were examined for quality and integrity by visual inspection, microstructure, and microhardness analysis. Visual inspection of the specimens welded by laser revealed the lack of root penetration at maximal welding speed from the selected welding speed range (30 to 60 mm/s) and a neat weld at the welding speed of 40 mm/s. However, in comparison to laser beam welding, the electron beam welding (EBW) process produced the weld joints with a wider heat affected zone, while the weld joints were much more prone to porosity. The microstructure of the weld joints made by both the laser beam welding and EBW methods did not show any abnormalities in phase composition owing to the presence of nitrides in the surface layer of the materials welded after nitro-oxidation.
{"title":"Comparison of the Laser and Electron Beam Welding of Steel Sheets Treated by Nitro-Oxidation","authors":"M. Marônek, J. Bárta, Katarína Bártová","doi":"10.1520/JAI103375","DOIUrl":"https://doi.org/10.1520/JAI103375","url":null,"abstract":"Nitro-oxidized steel specimens welded by a CO2 laser and an electron beam were examined for quality and integrity by visual inspection, microstructure, and microhardness analysis. Visual inspection of the specimens welded by laser revealed the lack of root penetration at maximal welding speed from the selected welding speed range (30 to 60 mm/s) and a neat weld at the welding speed of 40 mm/s. However, in comparison to laser beam welding, the electron beam welding (EBW) process produced the weld joints with a wider heat affected zone, while the weld joints were much more prone to porosity. The microstructure of the weld joints made by both the laser beam welding and EBW methods did not show any abnormalities in phase composition owing to the presence of nitrides in the surface layer of the materials welded after nitro-oxidation.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74859325","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}
To estimate the temperature distribution, stress distribution, and stress direction in a blade in service, the morphology of γ′ precipitates in Ni-based superalloy serviced in the first stage low pressure turbine (1st LPT) blade of a jet engine was investigated before and after aging. Using a field emission scanning electron microscope, microstructures were observed in forty portions of the blade. Most of the γ′ precipitates remained cuboidal in the serviced blade. Many secondary γ′ precipitates were observed in the γ matrix at the root part. In contrast, there were no secondary γ′ precipitates at the leading edge of the tip part. After simple aging, low-completion rafted γ/γ′ structures appeared on the suction side of the 70 mm part, while in other portions, coarsening of the γ′ precipitates was observed. Therefore, the leading edge of the 1st LPT blade tip was exposed to the highest temperatures in service. However, the stresses were extremely low in all portions of the blade.
{"title":"Morphology of γ′ Precipitates in a First Stage Low Pressure Turbine Blade of a Ni-Based Superalloy after Service and after Following Aging","authors":"N. Miura, Y. Kondo","doi":"10.1520/JAI103463","DOIUrl":"https://doi.org/10.1520/JAI103463","url":null,"abstract":"To estimate the temperature distribution, stress distribution, and stress direction in a blade in service, the morphology of γ′ precipitates in Ni-based superalloy serviced in the first stage low pressure turbine (1st LPT) blade of a jet engine was investigated before and after aging. Using a field emission scanning electron microscope, microstructures were observed in forty portions of the blade. Most of the γ′ precipitates remained cuboidal in the serviced blade. Many secondary γ′ precipitates were observed in the γ matrix at the root part. In contrast, there were no secondary γ′ precipitates at the leading edge of the tip part. After simple aging, low-completion rafted γ/γ′ structures appeared on the suction side of the 70 mm part, while in other portions, coarsening of the γ′ precipitates was observed. Therefore, the leading edge of the 1st LPT blade tip was exposed to the highest temperatures in service. However, the stresses were extremely low in all portions of the blade.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91281110","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}
With over 200 million individuals participating in alpine skiing and snowboarding worldwide, the number of trauma-related cases and fatalities are on the rise. Traumatic brain injuries (TBI) in particular, are the most common cause of serious injury and death among skiers and snowboarders, with young participants being identified at greater risk for head injury than adults. The purpose of this study is to evaluate the influence of head mass and geometry on the impact performance of alpine ski helmets in laboratory conditions. To accomplish this, extra large helmets were tested on a monorail drop system, with different mass and geometry conditions. The results indicate that the helmets tested with a heavier mass headform yielded lower linear accelerations than the other conditions. The geometry condition indicates that the helmets tested with the smaller headform yield lower accelerations, which implies that materials respond differently depending on the impact footprint. This could indicate that the mass difference and geometry of the headform are an important factor in the performance of helmet liners under laboratory test conditions. KEYWORDS: traumatic brain injury, alpine helmets, impact biomechanics Language: en
{"title":"The Influence of Headform Circumference and Mass on Alpine Ski Helmet Performance in Laboratory Tests","authors":"A. Post, G. Gimbel, T. Hoshizaki","doi":"10.1520/JAI103978","DOIUrl":"https://doi.org/10.1520/JAI103978","url":null,"abstract":"With over 200 million individuals participating in alpine skiing and snowboarding worldwide, the number of trauma-related cases and fatalities are on the rise. Traumatic brain injuries (TBI) in particular, are the most common cause of serious injury and death among skiers and snowboarders, with young participants being identified at greater risk for head injury than adults. The purpose of this study is to evaluate the influence of head mass and geometry on the impact performance of alpine ski helmets in laboratory conditions. To accomplish this, extra large helmets were tested on a monorail drop system, with different mass and geometry conditions. The results indicate that the helmets tested with a heavier mass headform yielded lower linear accelerations than the other conditions. The geometry condition indicates that the helmets tested with the smaller headform yield lower accelerations, which implies that materials respond differently depending on the impact footprint. This could indicate that the mass difference and geometry of the headform are an important factor in the performance of helmet liners under laboratory test conditions. KEYWORDS: traumatic brain injury, alpine helmets, impact biomechanics Language: en","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82912278","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}
Bent glass has garnered increased interest on the part of architects for the realization of curved glass facades. As one method of bending of glass facade units, cold bending is an economically efficient procedure for manufacturing; however, it introduces permanent stresses in the glazing structure, especially in the corner zones of the glass units for warped designs. In a similar manner, high stresses in the corner zones are also generated in general by constant surface loads acting on the panes of the glass unit, which can be explained by thin plate theory. Thus it can be expected that these unsteady loads, e.g., evoked by wind and/or snow loads, unfavorably interfere with the permanent stresses in the adhesives of both the structural glazing sealant and the insulating glass sealant from a durability point of view. The existence of these corner loads is not adequately accounted for by the ETAG 002 guideline for structural glazing applications, which postulates a trapezoidal load distribution in the bonding with diminishing stresses in the corner zones. This paper presents numerical results of a parametric study of pressure-loaded glass units, with a focus on corner loads and stresses. The results show that the stress levels in the corner zones might be significantly higher than the design stress values used for sizing the bonding.
{"title":"Glass Unit Corner Loading—Key Parameter in Durability","authors":"A. Hagl, O. Dieterich","doi":"10.1520/JAI104229","DOIUrl":"https://doi.org/10.1520/JAI104229","url":null,"abstract":"Bent glass has garnered increased interest on the part of architects for the realization of curved glass facades. As one method of bending of glass facade units, cold bending is an economically efficient procedure for manufacturing; however, it introduces permanent stresses in the glazing structure, especially in the corner zones of the glass units for warped designs. In a similar manner, high stresses in the corner zones are also generated in general by constant surface loads acting on the panes of the glass unit, which can be explained by thin plate theory. Thus it can be expected that these unsteady loads, e.g., evoked by wind and/or snow loads, unfavorably interfere with the permanent stresses in the adhesives of both the structural glazing sealant and the insulating glass sealant from a durability point of view. The existence of these corner loads is not adequately accounted for by the ETAG 002 guideline for structural glazing applications, which postulates a trapezoidal load distribution in the bonding with diminishing stresses in the corner zones. This paper presents numerical results of a parametric study of pressure-loaded glass units, with a focus on corner loads and stresses. The results show that the stress levels in the corner zones might be significantly higher than the design stress values used for sizing the bonding.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90787126","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}
Pervious concrete is a paving material that has a number of stormwater and other environmental benefits. Most current applications of pervious concrete are in residential streets, parking lots, driveways, and sidewalks, and it is being considered for shoulders and more high volume applications. Characterizations of stress distribution and deflection patterns in pervious concrete systems may be useful parameters in the structural design of these high volume uses. Pervious concrete panels with tandem axle dual wheel loads were analyzed using finite element analysis. The wheel position was considered in the corner, center, and edge of the pavement. The critical stresses obtained from the analyses were compared against experimental tensile and compressive strengths obtained from samples from a field application for various pervious concrete layer thicknesses, and additional experimental data. It was found that pervious concrete panels of sufficient thickness have adequate strength to support the applied wheel loads. To compare the long term performance when subjected to cyclic loading, the critical tensile stresses for various pavement thicknesses were compared with pavement condition index (PCI) rating data obtained from a field application reflecting pavement performance of approximately 131,000 cycles of an 80 kN single-axle load. For this particular field application, it was found that, for cyclic loading, the required thickness of the pervious concrete layer was approximately 40 %–80 % higher compared with that for the static loading condition.
{"title":"Validation of the Performance of Pervious Concrete in a Field Application with Finite Element Analysis","authors":"M. A. Alam, L. Haselbach, W. Cofer","doi":"10.1520/JAI104553","DOIUrl":"https://doi.org/10.1520/JAI104553","url":null,"abstract":"Pervious concrete is a paving material that has a number of stormwater and other environmental benefits. Most current applications of pervious concrete are in residential streets, parking lots, driveways, and sidewalks, and it is being considered for shoulders and more high volume applications. Characterizations of stress distribution and deflection patterns in pervious concrete systems may be useful parameters in the structural design of these high volume uses. Pervious concrete panels with tandem axle dual wheel loads were analyzed using finite element analysis. The wheel position was considered in the corner, center, and edge of the pavement. The critical stresses obtained from the analyses were compared against experimental tensile and compressive strengths obtained from samples from a field application for various pervious concrete layer thicknesses, and additional experimental data. It was found that pervious concrete panels of sufficient thickness have adequate strength to support the applied wheel loads. To compare the long term performance when subjected to cyclic loading, the critical tensile stresses for various pavement thicknesses were compared with pavement condition index (PCI) rating data obtained from a field application reflecting pavement performance of approximately 131,000 cycles of an 80 kN single-axle load. For this particular field application, it was found that, for cyclic loading, the required thickness of the pervious concrete layer was approximately 40 %–80 % higher compared with that for the static loading condition.","PeriodicalId":15057,"journal":{"name":"Journal of Astm International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74518499","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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