“…In a previous study, experimental and numerical investigations were conducted to clarify the deformation mode, resistance, and energy absorption of corrugated sandwich panels under impact loading. 19 The prototype was a metal-corrugated sandwich panel designed based on the principle of mass equivalence. A global coordinate system was defined (Figure 1) to clarify the different loading directions, where x , y , and z indicate the transverse, out-of-plane, and longitudinal directions of the sandwich panel, respectively.Figure 1.Geometric parameters of the corrugated sandwich panel.…”
Section: Dynamic Response Investigation Of Full-size Corrugated Sandw...mentioning
confidence: 99%
“…Considering the strain hardening of the material, the combined material relationship was applied to express the stress–strain relationship for the numerical simulation (Figure 3) in our previous study. 19 The stress–strain curve for the scaled model may not be available for designing the scaling test; hence, the Cowper–Symonds (CS) or JC equation is more convenient when the material coefficients are determined based on the true stress–strain histories of the prototype. Conversely, when the material parameters of the model are known, the response of the prototype can be derived from the determined model response when the appropriate scaling laws are applied.Figure 3.Combined material relationship.…”
Section: Dynamic Response Investigation Of Full-size Corrugated Sandw...mentioning
confidence: 99%
“…Figure 3 shows the combined material relationships used in our previous study. 19 The coefficient A in the JC constitutive equation is the yielding stress, whose value is 275 MPa, as determined based on the stress corresponding to a 0.2% strain from a quasi-static tensile test. In numerical simulations, the reference strain rate is typically set to trueε˙0=1s−1.…”
Section: Dynamic Response Investigation Of Full-size Corrugated Sandw...mentioning
The majority of the experimental studies investigating the dynamic response of sandwich panels are conducted using small-scale models that cannot be applied directly in the marine industry. In this study, a velocity–stress–mass (VSG) method based on the Johnson–Cook equation (VSG–JC) is derived to determine the relationship between a full-size structure (prototype) and its scaled-down model. The developed methodology is verified using theoretical and numerical solutions for an impact-loaded beam and plate, respectively. Theoretically, the model response can explicitly predict the behavior of a full-size structure using the VSG–JC method, whereas the strain rate cannot be obtained precisely via numerical simulation; hence, the corrected results for the model deviate slightly from the prototype results. Additionally, this method is compared with the VSG method based on the Cowper–Symonds equation (VSG–CS) in the numerical simulation of sandwich panels. The comparison results indicates that the VSG–JC method is more accurate than the VSG–CS method. The dynamic response of the scaled models predicted using the VSG–JC method coincides with that of the prototype, thus demonstrating that the VSG–JC method is valid for evaluating the scaling behavior of sandwich structures subjected to impact loads.
“…In a previous study, experimental and numerical investigations were conducted to clarify the deformation mode, resistance, and energy absorption of corrugated sandwich panels under impact loading. 19 The prototype was a metal-corrugated sandwich panel designed based on the principle of mass equivalence. A global coordinate system was defined (Figure 1) to clarify the different loading directions, where x , y , and z indicate the transverse, out-of-plane, and longitudinal directions of the sandwich panel, respectively.Figure 1.Geometric parameters of the corrugated sandwich panel.…”
Section: Dynamic Response Investigation Of Full-size Corrugated Sandw...mentioning
confidence: 99%
“…Considering the strain hardening of the material, the combined material relationship was applied to express the stress–strain relationship for the numerical simulation (Figure 3) in our previous study. 19 The stress–strain curve for the scaled model may not be available for designing the scaling test; hence, the Cowper–Symonds (CS) or JC equation is more convenient when the material coefficients are determined based on the true stress–strain histories of the prototype. Conversely, when the material parameters of the model are known, the response of the prototype can be derived from the determined model response when the appropriate scaling laws are applied.Figure 3.Combined material relationship.…”
Section: Dynamic Response Investigation Of Full-size Corrugated Sandw...mentioning
confidence: 99%
“…Figure 3 shows the combined material relationships used in our previous study. 19 The coefficient A in the JC constitutive equation is the yielding stress, whose value is 275 MPa, as determined based on the stress corresponding to a 0.2% strain from a quasi-static tensile test. In numerical simulations, the reference strain rate is typically set to trueε˙0=1s−1.…”
Section: Dynamic Response Investigation Of Full-size Corrugated Sandw...mentioning
The majority of the experimental studies investigating the dynamic response of sandwich panels are conducted using small-scale models that cannot be applied directly in the marine industry. In this study, a velocity–stress–mass (VSG) method based on the Johnson–Cook equation (VSG–JC) is derived to determine the relationship between a full-size structure (prototype) and its scaled-down model. The developed methodology is verified using theoretical and numerical solutions for an impact-loaded beam and plate, respectively. Theoretically, the model response can explicitly predict the behavior of a full-size structure using the VSG–JC method, whereas the strain rate cannot be obtained precisely via numerical simulation; hence, the corrected results for the model deviate slightly from the prototype results. Additionally, this method is compared with the VSG method based on the Cowper–Symonds equation (VSG–CS) in the numerical simulation of sandwich panels. The comparison results indicates that the VSG–JC method is more accurate than the VSG–CS method. The dynamic response of the scaled models predicted using the VSG–JC method coincides with that of the prototype, thus demonstrating that the VSG–JC method is valid for evaluating the scaling behavior of sandwich structures subjected to impact loads.
“…As to the issue, it is more scientific and objective to explore the current research based on experimental validations than pure computer simulation, for the quality of computer simulation depends on algorithms to a great extent [35,36,37]. Furthermore, simulation itself needs experimental validation to check its validity and correctness [38,39]. Small variation in configuring initial conditions for computer simulations may lead to a large discrepancy in results, while it is more robust when it comes to a real dynamic test.…”
Infant carriers play an important role in protecting child occupants from severe injuries caused by collisions, but the tension of harness webbing cannot be controlled properly most of the time. Infant carrier’s user manual or instruction generally contains little information about the extent to which the adjusting belt should be pulled to cause the necessary webbing tension, and it is often neglected that the infants should be restrained securely. In order to improve public awareness, it is important to ascertain the effect of infant carrier’s webbing tension on the occupant’s chest accelerations. A testing scheme including 12 dynamic tests was devised and conducted, and test conditions were controlled strictly to ensure the accuracy and objectivity of results. P1.5 dummy’s resultant and vertical chest accelerations were collected and analyzed. Both ISOFIX installation and seat belt installation methods were taken into consideration without lack of generality. Sled’s accelerations and velocities were set and acquired, which constituted the fundamental testing conditions of dynamic tests and ensured the repeatability and reliability of tests. Furthermore, dummy’s chest acceleration pulses were monitored and recorded, and the data were evaluated in accordance with criteria defined in relevant technical standards. The dummy’s chest accelerations were classified into 2 groups according to child restraint systems’ installation methods, i.e., the ISOFIX group and the seat belt group. In each group, both resultant chest acceleration and vertical chest acceleration were involved. Universal phenomena were displayed in all the tests, and the larger the tensile forces were, the lower the chest accelerations were in tests. Based on experimental validations, the relation between webbing’s tensions and chest accelerations in frontal crash accidents was verified. Furthermore, suggestions were made about adjusting the webbing tension and the proper use of infant carriers.
“…[ 25 ], Cheng et al. [ 26 ] found that the transverse impact resistance behavior of the U-type corrugated core sandwich panel was better than the longitudinal behavior by numerical simulation and drop hammer impact test. However, there is little difference between the drop weight area and the unit area in the study.…”
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