Test Method for Drop Test of Loaded Containers by Free Fall

2017 ◽  
Author(s):  
Keyword(s):  
Free Fall ◽  
Test Method ◽  
Drop Test

scholarly journals Numerical Model Study of Prototype Drop Tests on Cube and Cubipod® Concrete Armor Units Using the Combined Finite–Discrete Element Method

2021 ◽  
Vol 9 (5) ◽  
pp. 460
Author(s):  
Giulio Scaravaglione ◽  
John-Paul Latham ◽  
Jiansheng Xiang
Keyword(s):  
Discrete Element Method ◽  
Validation Study ◽  
Free Fall ◽  
Discrete Element ◽  
Drop Test ◽  
Modeling Methodology ◽  
Model Study ◽  
Drop Tests ◽  
Rubble Mound Breakwaters ◽  
Element Method

This paper aims to evaluate the structural strength of unreinforced concrete armor units (CAU), named Cubipod®, used on rubble-mound breakwaters and coastal structures, through a numerical methodology using the combined finite–discrete element method (FDEM). A numerical modeling methodology is developed to reproduce the results of an experimental examination published by Medina et al. (2011) of a free-fall drop test performed on a 15 t conventional Cubic block and a 16 t Cubipod® unit. The field results of the Cube drop tests were used to calibrate the model. The numerically simulated response to the Cubipod® test is then discussed in the context of a validation study. The calibration process and validation study provide insights into the sensitivity of breakage to tensile strength and collision angle, as well as a better understanding of the crushing and cracking damage of this unit under drop test impact conditions.

scholarly journals Manufacture and Strength Analysis of Ergonomic Bicycle Helmet Made from Polymeric Foam Composite Strengthened by Oil Palm Empty Fruit Bunch Fiber with Free Fall Drop Test Method

2020 ◽  
Vol 64 (1) ◽  
pp. 33-38
Author(s):  
Mahadi Mahadi ◽  
Keyword(s):  
Oil Palm ◽  
Free Fall ◽  
Product Safety ◽  
Drop Test ◽  
Empty Fruit Bunch ◽  
Test Results ◽  
Shell Layer ◽  
Bicycle Helmet ◽  
Polymeric Foam ◽  
Foam Composite

This article contains a study report on the manufacturing of bicycle helmet models that use polymeric foam composite materials strengthened by oil palm empty fruit bunch (OPEFB). The test results of mechanical polymeric foam obtain tensile stress (σt) 1.17 MPa, compressive stress (σc) 0.51 MPa, bending stress (σb) 3.94 MPa, modulus of elasticity (E) 37.97 MPa, density ( ρ) 193 (kg / m3). The testing results of thermal conductivity (k) with ASTM C177-04 standard obtain 0.096 W/mK. Aerodynamic simulation is carried out on 5 bicycle helmet models with different variations of air ventilation formations and obtained the M4A model that best met the ergonomic criteria. The simulation results of the M4A helmet model are max 65.668 Pa of air pressure (Pu), 26,8 0C of inner wall temperature (Ti), 11.0724 m/s of air velocity (vi) and 0.89 of drag coefficient (CD). Bicycle helmet manufacturing is carried out by hand lay up method for shell layer and casting mold for liner by using GFRP polymer composite molds. Both layers are made by sandwich method with the composition of the shell layer is 100 grams resin, 15 grams glass fiber and 5 grams catalyst. The composition of the liner layer is 275 grams (50%) of unsaturated Polyester 157 BQTN-EX resin, 27.5 grams (5%) of OPEFB fiber, 247 grams (45%) of Blowing Agent Polyurethane and 27.5 grams (5%) of Methyl Ketone Perokside catalyst (MEKPO). The toughness of the helmet is tested by using a free fall drop test with the standard of Consumer Product Safety Commission (CPSC) with the height of impact 1.5 meters. The free fall drop test results are max 2.02 MPa of the impact stress of the M4A bicycle helmet model (σi) and max 283.77 joules of energy impact (Ei) which is close to the Consumer Product Safety Commission’s (CPSC) standard value of 110 joules.

Head Impact Modeling to Support a Rotational Combat Helmet Drop Test

2021 ◽  
Author(s):  
Ryan Terpsma ◽  
Rika Wright Carlsen ◽  
Ron Szalkowski ◽  
Sushant Malave ◽  
Alice Lux Fawzi ◽  
...  
Keyword(s):  
Human Head ◽  
Mechanical Stimulus ◽  
Scientific Basis ◽  
Test Method ◽  
Drop Test ◽  
Head Impacts ◽  
Digital Twin ◽  
Brain Deformation ◽  
Acceleration Time Histories ◽  
Hybrid Iii

ABSTRACT Introduction The Advanced Combat Helmet (ACH) military specification (mil-spec) provides blunt impact acceleration criteria that must be met before use by the U.S. warfighter. The specification, which requires a helmeted magnesium Department of Transportation (DOT) headform to be dropped onto a steel hemispherical target, results in a translational headform impact response. Relative to translations, rotations of the head generate higher brain tissue strains. Excessive strain has been implicated as a mechanical stimulus leading to traumatic brain injury (TBI). We hypothesized that the linear constrained drop test method of the ACH specification underreports the potential for TBI. Materials and Methods To establish a baseline of translational acceleration time histories, we conducted linear constrained drop tests based on the ACH specification and then performed simulations of the same to verify agreement between experiment and simulation. We then produced a high-fidelity human head digital twin and verified that biological tissue responses matched experimental results. Next, we altered the ACH experimental configuration to use a helmeted Hybrid III headform, a freefall cradle, and an inclined anvil target. This new, modified configuration allowed both a translational and a rotational headform response. We applied this experimental rotation response to the skull of our human digital twin and compared brain deformation relative to the translational baseline. Results The modified configuration produced brain strains that were 4.3 times the brain strains from the linear constrained configuration. Conclusions We provide a scientific basis to motivate revision of the ACH mil-spec to include a rotational component, which would enhance the test’s relevance to TBI arising from severe head impacts.

Failure Analysis of the Solder Joints in Flip-Chip BGA Packages under Free-Drop Test

2014 ◽  
Vol 936 ◽  
pp. 628-632 ◽  
Author(s):  
Guo Zheng Yuan ◽  
Xia Chen ◽  
Xue Feng Shu
Keyword(s):  
Flip Chip ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Test Method ◽  
Drop Test ◽  
Test Reliability ◽  
Internal Crack ◽  
The Real ◽  
Plastic Ball ◽  
Free Drop

The failure of plastic ball grid array under intense dynamic loading was studied in the project. This paper presents the drop test reliability results of SnPb flip-chip on a standard JEDEC drop reliability test board. The failure mode and mechanism of planar array package in the drop test was comprehensively analyzed. High acceleration dropping test method was used to research the reliability of BGA (ball grid array) packages during the free-drop impact process. The model RS-DP-03A drop device was used to simulate the falling behavior of BGA chip packages under the real conditions, The drop condition meets the JEDEC22-B111 standards (pulse peak 1500g, pulse duration 0.5 ms) when dropping from the 650mm height . In the testing, according to the real-time changes of dynamic voltage, the relationship between drop times and different phases of package failure was analyzed. With the dye-penetrated method and optical microscopy, it was easy to observe the internal crack and failure locations. The growth mechanism of the cracks in solder joints under the condition of drop-free was analyzed and discussed.

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