Crashworthiness of Composites and Lightweight Structures最新文献

{"title":"Stochastic Applications in Crashworthiness","authors":"R. Koganti, A. Caliskan","doi":"10.1115/imece2001/amd-25433","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25433","url":null,"abstract":"\u0000 Due to geometrical, and material property variations, response of any structural member varies from the nominal design value. Typically the geometrical and material variations are the resultant of manufacturing variations. In this paper, the effect of these variations about the nominal values on structural response is studied using stochastic or probabilistic methods. Circular aluminum cross-sections are becoming popular in structural energy management applications. Also, significant research has been done to estimate the mean crush load for a circular section using empirical relations. An empirical relation, which is a function of thickness, outer radius, elastic modulus and yield strength, was used to estimate the mean crush load. Based on the measured thickness, outer radius and yield strength, the mean crush load is calculated using the empirical relation. Also, using the empirical relation, the variation in the mean crush load is estimated using linear statistical approach and Monte-Carlo simulation. In both the stochastic methods, actual mean and standard deviations of thickness, outer radius and yield strength are used. Also, using the extreme variations of these factors, mean crush load is predicted using an implicit Finite Element Analysis (FEA) code. The FEA prediction is in good agreement with the results of the testing. However, the designed mean crush load based on the empirical relation overestimates the crush loads by about 11%. The results of the study showed that the tube thickness and yield strength variations significantly affect the crush loads. Based on the Monte-Carlo simulation and FEA values using the extreme values for the geometrical and mechanical properties, one can design crash structures that take into account the inherent variability of components.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122777718","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}

{"title":"Behavior of Composite Materials Under Impact: Strain Rate Effects, Damage, and Plasticity","authors":"S. Abrate","doi":"10.1115/imece2001/amd-25428","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25428","url":null,"abstract":"\u0000 Composite materials are often subjected to low velocity impacts, ballistic impacts, or crash impacts. In order to analyze such events, realistic model of the material behavior must be used to capture phenomena no included in linear elastic models. Nonlinear behavior occurs when a unidirectional lamina is loaded in the transverse direction or in shear when the matrix material deforms plastically. The stiffness and strength of composite materials at high strain rates is often very different from what is measured in quasi-static tests. In addition, different types of damage are introduced during impart: matrix cracks, delaminations, fiber failures, fiber-matrix debonding. The introduction of this damage will affect the subsequent behavior of the material.\u0000 Many different approaches have been taken to account for the effects of strain rate, plasticity and damage on the mechanical behavior of composite materials. The objective of this paper is to assess current knowledge in this area, review and compare models used to describe the stress-strain behavior and predict failure of such materials. Continuum mechanics approaches are used to describe the behavior of laminas with different types of damage, and to model the behavior of interfaces between plies. Phenomenological plasticity models account for the nonlinear effects under transverse and shear loads. Some of these models are shown to be similar even though they were derived by very different approaches. Many accurate analyses of composite structures under impact assume linear elastic behavior and do not considered the complicating effects discussed here. The applicability of the different models for material behavior is also discussed in terms of selecting an appropriate model for analyzing a particular impact.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"228 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134108378","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}

{"title":"Influence of Chassis and Driveline Components in Vehicle Frontal Crash","authors":"N. Saha, Rabin Bhojan","doi":"10.1115/imece2001/amd-25434","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25434","url":null,"abstract":"\u0000 With increased focus on new vehicle crash safety, vehicle structures are being developed to sustain more demanding frontal crash conditions such as, offset, angular, and pole impacts. To manage the higher amount of impact energy, vehicle body components are designed for higher strength and stiffness resulting in increased vehicle weight. As an alternative, a more efficient design concept involving the chassis, suspension and driveline components are studied here. Attempts are made to investigate how the non-body structure components of a vehicle can be deployed to absorb crash energy that may lessen the demand on the body-in-white. Contribution of underbody chassis subframe & cross-members, the suspension control arms and the drive-shaft components are evaluated using analytical methods for effective use in frontal impact conditions. Ideas are explored to improve the vehicle crash pulse and reduce passenger compartment intrusions in frontal impacts by employing sub-frame, drive shaft and suspension control arms more effectively.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124413248","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}

{"title":"Frontal Impact Test and Analysis on an Aluminum Front-End Structure","authors":"A. Caliskan, R. Koganti","doi":"10.1115/imece2001/amd-25436","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25436","url":null,"abstract":"\u0000 A frontal impact test was performed on a front-end module consisting of 6xxx series aluminum extrusions, and some 5xxx series aluminum stampings as reinforcements. The front end structure consists mainly of a bumper, cross member, radiator support, front and backup lower rails, upper rails, and shock tower support. In addition to the main structure, a subframe containing the engine was also attached to the back-up rails. The front-end module was mounted on a sled at the upper and lower A-pillar points as well as at the back-up rail. In addition to measuring the barrier forces, load cells were located behind the main structural members to determine load transfer. The results of the tests showed progressive folding of the crush rails, and adequate absorption of the impact energy. To aid in the design, a CAE model of the front-end was created to determine the crash behavior of the structure during frontal impact. The final model, which took into account, the material properties of the weld joints showed good agreement with test results.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121976910","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}

{"title":"Crashing Behavior of Braided Composites","authors":"H. Hamada","doi":"10.1115/imece2001/amd-25427","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25427","url":null,"abstract":"\u0000 FRP exhibits not only the excellent strength to weight than conventional metallic materials, but also high energy absorption properties. Therefore FRP would be applied to structural components for various vehicles recently. Particularly, braided composites are expected to utilize for safety components, because they show the fracture mode called progressive crushing, which proceeds under constant load. Energy absorption with progressive crushing was generated by combination of fiber fracture, delamination, crack, etc. In this paper, the crushing properties, especially fracture mechanisms of FRP rods were investigated. To discuss the fracture morphology, microscopic observations were examined.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127635737","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}

{"title":"Static and Impact Behavior of Self-Pierced Rivet Connections in Aluminum","authors":"C. Madasamy, O. Faruque, T. Tyan, Robert Thomas","doi":"10.1115/imece2001/amd-25431","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25431","url":null,"abstract":"\u0000 Self-pierced riveted (SPR) connections in aluminum coupons were tested to evaluate their static and impact performance for automotive vehicle applications. The variables studied included: top gage, bottom gage, rivet size, adhesive, pre-strain, rivet location, strain-rate, and temperature. The SPR connections were tested for coach peel, u-tension, and lap shear modes. A variable importance assessment as well as the estimated effect of the variables on peak force and energy absorption was determined. The failure modes observed during testing were consistent. From this study, it was found that the top gage, bottom gage, and temperature were very sensitive for coach peel, u-tension, and lap shear. Additionally, adhesive was found to be important for shear loading, strain-rate increased the peak force when adhesive was present and, rivet size had a significant effect on both u-tension and coach peel modes. The effect of pre-strain and rivet location was minimal, and therefore their effect in the design process can be considered minimal.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126805209","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}

{"title":"The Role of Adhesive in the Load Response of Adhesively Bonded Aluminum Hat Sections Under Axial Compression","authors":"Jianping Lu, G. Newaz, R. Gibson","doi":"10.1115/imece2001/amd-25425","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25425","url":null,"abstract":"\u0000 Aluminum hat section, either adhesively bonded or unbonded, experiences buckling, post buckling and plastic collapse when axially compressed. However, there exist obvious differences in the load response between the bonded and unbonded hat sections. Finite element eigenvalue buckling analysis is carried out to predict the buckling load and mode. Experiments show that when adhesively bonded hat sections begin to buckle there is a transformation from the first buckling mode to the higher ones, while the unbonded hat sections develop the post buckling based on the lowest buckling mode. The different buckling modes result in not only different buckling loads but different peak loads of the hat sections as well. Finally, the ultimate compressive strength formulae are proposed for the hat sections.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133299283","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}

{"title":"Studies on Headform Impact Design","authors":"A. Deb","doi":"10.1115/imece2001/amd-25432","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25432","url":null,"abstract":"\u0000 HIC(d) (Head Injury Criterion, dummy) is defined as a kinematic relationship involving resultant translational deceleration at the CG (center of gravity) of a biofidelic headform and duration of contact. As deceleration response of a headform is in general a function of the energy-absorbing and geometrical properties of an obstructing structure (for a given impact speed), HIC(d) can be expressed, at least symbolically, as a function of those properties. The current paper uses a simplified mathematical model to capture the worst case of headform impact as considered in the FMVSS 201 regulation for upper interior head impact. The obstructing structural countermeasure in the path of a colliding headform is assumed to possess idealized elastoplastic although physically relevant behavior under loading. During the process of designing for headform impact safety compliance, which often turns out to be a trial-and-error process, it is sometimes difficult to see the correspondence between HIC(d) and the relative effectiveness of design iterations in terms of energy-absorption. Thus, relationship between HIC(d) and energy absorbed by such structural countermeasures is investigated. Based on results obtained from the current model and a new approach, an explicit relationship is derived between HIC(d) and the characteristic properties of an energy-absorbing countermeasure that can be used as a design aid.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116290792","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}

{"title":"Dynamic Crush Test of Subcomponent Composite Front Frame Rails","authors":"Thomas J. Brimhall, Hasetetsion G. Mariam","doi":"10.1115/imece2001/amd-25426","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25426","url":null,"abstract":"\u0000 Testing of components is a usual method to evaluate structures, joining methods, and materials prior to full scale testing. Ambient temperature dynamic crush testing was performed on steel and composite sub-component front frame rails to compare the energy absorption and evaluate crush behavior. The sub-component composite frame rails were fabricated from two parts, an upper and lower, and bonded using three adhesives: Ashland polyurethane, Lord epoxy, and 3M epoxy. Prior to the dynamic test of the rails, single lap shear coupon tests were performed at ambient temperature and elevated temperature, 135°C, to evaluate relative bond strength of these adhesives. Testing was performed at elevated temperature because adhesives used for structural bonding in automotive, specifically under-hood, applications can be subjected to elevated temperatures. All three adhesives tested showed reduced bond strength at elevated temperatures. At room temperature, the Ashland urethane and Lord epoxy adhesives were observed to have comparable higher bond strength with the composite-to-composite lap shear coupons compared to the 3M epoxy. However, the crush failure mode for the composite tubes was confined to the substrate and the mean crush load was independent of the adhesive used for fabrication.\u0000 Progressive crushing of the rail specimens was observed for all specimens tested. The amount of energy absorbed and crush mode for each rail design depended on its structural and material characteristics. The steel specimen absorbed energy by localized buckling in an accordion crush mode. The composite specimens absorbed energy by fracturing the composite matrix, delamination, fracture of the reinforcement fibers, and friction between the fracture and crushing surfaces. The crushing process of the steel rail was initiated by fabricated corrugations in the rail comers at the front, or impact, end of the rail. The composite rail crush event was initiated with an aluminum plug trigger designed to cause the composite rail to split at the comers with fracture of the composite matrix and delamination of the composite plies. Glass fibers were observed to fracture primarily at the tube corners. Fiber fracture elsewhere was infrequent. Close examination of the bonded joint fracture surface showed extensive fiber tear-out indicating that the failure was in the composite, not the adhesive. Mean crush load for the steel rail was 60% higher than the average mean load for the composite rails. The peak load for the steel rail was 71% higher than the average peak load for the composite rails. Specific energy absorption (SEA) of the steel rail was calculated to be 6.34 kJ/kgm compared with an average of 10.5 kJ/kgm for the composite rails.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129935731","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}

{"title":"The High Velocity Impact Response of Novel Fiber Metal Laminates","authors":"W. Cantwell, Graham Wade, J. F. Guillen, G. Reyes-Villanueva, N. Jones, P. Compston","doi":"10.1115/imece2001/amd-25423","DOIUrl":"https://doi.org/10.1115/imece2001/amd-25423","url":null,"abstract":"\u0000 The impact resistance of a range of novel fiber metal laminates based on polypropylene, polyamide and polyetherimide matrices has been investigated. Initial attention focused on optimizing the interface between the composite and aluminum alloy constituents. Here, it was shown that composite-metal adhesion was excellent in all systems examined. In addition, tests at crosshead displacement rates up to 3 m/s indicated that the interfacial fracture energies remained high under dynamic loading conditions.\u0000 High velocity impact tests on a series of 3/2 laminates (3 layers of aluminum/2 layers of composite) highlighted the outstanding impact resistance of a number of these systems. The glass fiber reinforced polypropylene system offered a particularly high impact resistance exhibiting a perforation energy of approximately 160 Joules. Here, failure mechanisms such as extensive plastic drawing in the aluminum layers and fiber fracture in the composite plies were found to contribute to the excellent energy-absorbing characteristics of these systems.","PeriodicalId":431388,"journal":{"name":"Crashworthiness of Composites and Lightweight Structures","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127000572","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}