Small Mass Impact Testing of Sandwich Structures

2010 ◽  
Vol 52 (11-12) ◽  
pp. 765-770 ◽  
Author(s):  
Stefan Dietrich ◽  
Jan Kuppinger ◽  
Peter Elsner ◽  
Kay Weidenmann
Keyword(s):  
Sandwich Structures ◽  
Small Mass ◽  
Impact Testing

scholarly journals Experimental Investigation on the Low Velocity Impact Response of Fibre Foam Metal Laminates

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5510
Author(s):  
Patryk Jakubczak ◽  
Magda Droździel ◽  
Piotr Podolak ◽  
Jesus Pernas-Sánchez
Keyword(s):  
Sandwich Structures ◽  
Impact Resistance ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Stress Concentrations ◽  
Fibre Metal Laminates ◽  
Matrix Cracks ◽  
Foam Metal ◽  
Fibre Metal ◽  
The Impact

The combination of fibre metal laminates (FML) and sandwich structures can significantly increase the performance under impact of FMLs. The goal of this work was to create a material that will combine the superior properties of FMLs and foam sandwich structures in terms of the impact resistance and simultaneously have lower density and fewer disadvantages related to the manufacturing. An extensive impact testing campaign has been done using conventional fibre metal laminates (carbon- and glass-based) and in the proposed fibre foam metal laminates to assess and compare their behaviour. The main difference was observed in the energy absorption mechanisms. The dominant failure mechanism for fibre foam laminates is the formation of delaminations and matrix cracks while in the conventional fibre metal laminate the main failure mode is fibre cracking due to high local stress concentrations. The reduction in the fibre cracking leads to a better after-impact resistance of this type of structure improving the safety of the structures manufactured with these materials.

The perforation resistance of sandwich structures subjected to low velocity projectile impact loading

2012 ◽  
Vol 116 (1186) ◽  
pp. 1247-1262 ◽  
Author(s):  
J. Zhou ◽  
Z. W. Guan ◽  
W. J. Cantwell
Keyword(s):  
Sandwich Structures ◽  
Sandwich Panels ◽  
Impact Testing ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Analysis Package ◽  
The Impact

Abstract This article presents the findings of a study to investigate the impact perforation resistance of sandwich structures. The dynamic response of sandwich panels based on PVC foam cores has been evaluated by determining the energy to perforate the panels. The impact response of the sandwich structures was predicted using the finite element analysis package Abaqus/Explicit. The validated FE models were also used to investigate the effect of oblique loading and to study the impact response of sandwich panels subjected to a pressure differential equivalent to flying at an altitude of 10,000m. Low velocity impact testing has shown that the energy to perforate the sandwich panels is dependent on the properties of the core. It has been shown that increasing the density of the crosslinked PVC foams by a factor of two yielded a 600% increase in the perforation resistance of the sandwich structures. At higher densities, the crosslinked foam sandwich structures offered a superior perforation resistance to the linear PVC structures. The numerical analysis accurately predicted the perforation energies of the sandwich panels, as well as the prevailing failure mechanisms following impact. Finally, it has been shown that sandwich panels impacted at high altitude offer a similar perforation resistance to those tested at sea level.

An Experimental Investigation on Composites Through-The-Thickness Stitched Foam Core Sandwich Panels

2007 ◽  
Vol 353-358 ◽  
pp. 1443-1446 ◽  
Author(s):  
Qin Sun ◽  
Xi Tao Zheng ◽  
Ye Li ◽  
Ya Nan Chai ◽  
Zheng Hua Cao
Keyword(s):  
Damage Tolerance ◽  
Sandwich Structures ◽  
Low Cost ◽  
Sandwich Panels ◽  
Mechanical Tests ◽  
Impact Testing ◽  
Compression Testing ◽  
Foam Core ◽  
Composite Sandwich ◽  
Compression After Impact

This study explored the feasibility and potential benefits provided by the addition of through-the-thickness reinforcement to foam core sandwich structures. Through-the-thickness stitching is proposed to increase the interlaminar strength and damage tolerance of composite sandwich structures. A low-cost, out-of-autoclave processing method was developed to produce composite sandwich panels with carbon fiber face sheets, a closed-cell foam core, and through-the-thickness Kevlar stitching. The sandwich panels were stitched in a dry preform state, vacuum bagged, and infiltrated using Vacuum Assisted Resin Transfer Molding (VARTM) processing. For comparison purposes, unstitched sandwich panels were produced using the same materials and manufacturing methodology. Five types of mechanical tests were performed: flexural testing, flatwise tensile and compression testing, core shear testing, and edgewise compression testing. Drop-weight impact testing followed by specimen sectioning was performed to characterize the damage resistance of stitched sandwich panels. Compression after impact (CAI) testing was performed to evaluate the damage tolerance of the sandwich panels. Results show significant increases in the flexural stiffness and strength, out-of-plane tensile strength, core shear strength, edgewise compression strength, and compression-after-impact strength of stitched sandwich structures.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

PARATHYROID HORMONE SECRETION IN DISORDERS OF CALCIUM METABOLISM STUDIED BY MEANS OF EDTA

1974 ◽  
Vol 75 (2) ◽  
pp. 286-296 ◽  
Author(s):  
J. H. Lockefeer ◽  
W. H. L. Hackeng ◽  
J. C. Birkenhäger
Keyword(s):  
Parathyroid Hormone ◽  
Primary Hyperparathyroidism ◽  
Calcium Metabolism ◽  
Hormone Secretion ◽  
Parathyroid Tissue ◽  
Small Mass ◽  
Idiopathic Hypercalciuria ◽  
List Type ◽  
Immunoreactive Parathyroid Hormone ◽  
Pth Level

ABSTRACT In 22 of 28 cases of primary hyperparathyroidism (PHP) the rise in the serum immunoreactive parathyroid hormone (IRPTH or PTH) level observed in response to lowering of the serum calcium by EDTA, exceeded that obtained in 8 control subjects. In 5 of these 22 patients who were studied again after parathyroidectomy the supranormal response was abolished. Fifteen of these 22 hyper-responsive PHP patients had basal IRPTH levels not exceeding the highest level in the controls and that of other groups of patients investigated (idiopathic hypercalciuria, non-parathyroid hypercalcaemia, operated PHP). Fourteen of the 22 hyper-reactive patients with PHP did not show hypocalcaemia during the infusion of EDTA. The extent of the release of PTH elicited by EDTA in cases of PHP does not as yet allow a prediction of the amount of pathological parathyroid tissue present, although all the PHP patients showing a normal release of PTH had a relatively small mass of parathyroid tissue (up to about 1 g) subsequently removed. In 9 cases of nephrolithiasis (8 of whom had idiopathic hypercalciuria) and in 7 cases of non-parathyroid hypercalcaemia, a normal PTH release was found.

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