Abstract:The work described herein consists of experimental measurement of the post-impact buckling loads of Eglass/epoxy laminates. Composite samples with stacking sequence of [+45/45/90/0] 2s were subjected to low-velocity impact loading at energy levels of 36, 56.13, 79.95, 110.31 and 144 J. The impact tests were conducted with a specially developed vertical drop weight testing machine. Impact parameters like peak load, absorbed energy, deflection at peak load and damage area were evaluated and compared. Damaged sp… Show more
“…These kinds of impact loads can be modeled with various dynamic tests, of which the falling weight impact test is the most commonly used. Figure 9 shows the general layout of such a measuring device 8,94,105 …”
Section: Investigating Methods Of Polymer Foamsmentioning
confidence: 99%
“…General layout of a falling weight impact tester. Reproduced under terms of the CC‐BY license 105 . Copyright 2021, Scientific Research Publishing…”
Section: Investigating Methods Of Polymer Foamsmentioning
confidence: 99%
“…Another commonly used layout is when the foam is placed on a solid support, mostly concrete, so the foam is not perforated. In this case, the evaluation is based on the maximum force or acceleration exerted on the weight 31,32,105 . This method is used by the sport‐specific standards presented earlier, and the material of packaging products is also selected on a similar principle.…”
Section: Investigating Methods Of Polymer Foamsmentioning
The use of polymer foams is becoming increasingly important due to the attainable weight reduction and value‐added properties. The development of foam structures is a popular research area as they have outstanding energy absorbing capability, which is related to the special deformation mechanisms of the cell structure (cell wall buckling and collapse of the cells). This property is exploited by the sports industry, where the main task of such products is to protect the health of the athlete and to ensure safe sports conditions. This review provides a comprehensive presentation of the advanced energy absorbing applications of polymeric foams in sports. The article presents in detail the processing technologies of polymer foams, as well as the sports‐specific regulations which contain the requirements for sports products. The impact damping of polymeric foams is typically determined by falling weight impact tests, which were used in several previous studies. However, it is a great challenge to compare the published results, as the test parameters and the tested materials are different. Currently, an unexplored field of research is the detailed study of multilayer sandwich foam structures. Understanding the effect of layer order on mechanical properties would help researchers achieve a major improvement in this field.
“…These kinds of impact loads can be modeled with various dynamic tests, of which the falling weight impact test is the most commonly used. Figure 9 shows the general layout of such a measuring device 8,94,105 …”
Section: Investigating Methods Of Polymer Foamsmentioning
confidence: 99%
“…General layout of a falling weight impact tester. Reproduced under terms of the CC‐BY license 105 . Copyright 2021, Scientific Research Publishing…”
Section: Investigating Methods Of Polymer Foamsmentioning
confidence: 99%
“…Another commonly used layout is when the foam is placed on a solid support, mostly concrete, so the foam is not perforated. In this case, the evaluation is based on the maximum force or acceleration exerted on the weight 31,32,105 . This method is used by the sport‐specific standards presented earlier, and the material of packaging products is also selected on a similar principle.…”
Section: Investigating Methods Of Polymer Foamsmentioning
The use of polymer foams is becoming increasingly important due to the attainable weight reduction and value‐added properties. The development of foam structures is a popular research area as they have outstanding energy absorbing capability, which is related to the special deformation mechanisms of the cell structure (cell wall buckling and collapse of the cells). This property is exploited by the sports industry, where the main task of such products is to protect the health of the athlete and to ensure safe sports conditions. This review provides a comprehensive presentation of the advanced energy absorbing applications of polymeric foams in sports. The article presents in detail the processing technologies of polymer foams, as well as the sports‐specific regulations which contain the requirements for sports products. The impact damping of polymeric foams is typically determined by falling weight impact tests, which were used in several previous studies. However, it is a great challenge to compare the published results, as the test parameters and the tested materials are different. Currently, an unexplored field of research is the detailed study of multilayer sandwich foam structures. Understanding the effect of layer order on mechanical properties would help researchers achieve a major improvement in this field.
“…The integral area under the load-displacement curve can be considered as the work the composite laminates applied onto the impactor. In general, the energy absorbed by the samples is designated as the difference between the energy at the end of the impact process and the energy at the maximum load point [34]. Because the CFRP composites are rigid, the energy before reaching the maximum load is considered to be absorbed by the elastic deformation, only the energy after the maximum load is devoted to producing damage.…”
Section: Characterization Of Impact Loads and Energiesmentioning
As a graphite derivative, graphite fluoride (GrF) has a remarkable fracture toughness improvement effect on epoxy materials. The fracture toughness variation of the epoxy could exert an influence on the low velocity impact resistance of the corresponding carbon fiber reinforced polymer (CFRP) composite. Therefore, the dependence of the low velocity impact resistance of the incorporated CFRP on the GrF content is worth analyzing. Here, different contents of GrF were applied to incorporate CFRP laminates and planned to find the optimal GrF content, in turn leading to the best impact resistance. Using a drop-weight impact test, the load vs. time curves and load vs. displacement curves were obtained. The incipient damage loads and maximum loads of various GrF contents of the samples were compared carefully. The absorbed energies during the impact process were calculated. The trend of absorbed energy decreased up to the 1 wt% sample, then increased significantly with the rise of GrF content. This deflection behavior can be explained by the combination of crack pinning, crack deflection and crack propagation, due to the rise in GrF content. Through the ultrasonic C-scan evaluation, the delamination areas of different GrF content of samples were measured. The trend of delamination area variation was accordant with the trend of absorbed energy variation. This presents a demonstration of the correlation between the absorbed energy and the damage level. The SEM images of the fracture surfaces were analyzed for the deflection behavior of the fracture toughness with various GrF contents. The plot of residual compression strength versus GrF content further indicated the 1 wt% was the optimal content at which the incorporated GrF endowed the most impact-resistant property to the CFRP laminates.
“…These impact loads are considered extremely dangerous and cause invisible damage to the back face or within the laminate which consequently reduce the strength of the composite material, even when the impact produces low energy. It has been proven that if a composite plate is subjected to a low velocity impact, the damaged area will increase with the increase of the impact velocity [ 1 ]. Caprino et al [ 2 ] concluded that the first failure point in a laminated composite plate is influenced more by the impact speed rather than the impacting energy.…”
This paper investigates the effects of localized interface progressive delamination
on the behavior of two-layer laminated composite plates when subjected to low velocity
impact loading for various fiber orientations. By means of finite element approach, the
laminae stiffnesses are constructed independently from their interface, where a well-defined virtually
zero-thickness interface element is discreetly adopted for delamination simulation.
The present model has the advantage of simulating a localized interfacial condition
at arbitrary locations, for various degeneration areas and intensities, under the influence
of numerous boundary conditions since the interfacial description is expressed discretely.
In comparison, the model shows good agreement with existing results from the literature
when modeled in a perfectly bonded state. It is found that as the local delamination area
increases, so does the magnitude of the maximum displacement history. Also, as top
and bottom fiber orientations deviation increases, both central deflection and energy
absorption increase although the relative maximum displacement correspondingly decreases
when in contrast to the laminates perfectly bonded state.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
