3D printed geometrically tessellated sheets with origami-inspired patterns

2021 ◽  
pp. 0021955X2110618
Author(s):  
Anastasia L. Wickeler ◽  
Hani E. Naguib
Keyword(s):  
Impact Energy ◽  
Single Layer ◽  
Impact Testing ◽  
Impact Loads ◽  
Geometrical Complexity ◽  
Impact Forces ◽  
3D Printed ◽  
The Impact ◽  
Multiple Configurations ◽  
Absorb Impact Energy

This study demonstrates that the impact energy absorption capabilities of flexible sheets can be significantly enhanced by implementing tessellated designs into their structure. Configurations of three tessellated geometries were tested; they included a triangular-based, a rectangular-based, and a novel square-based pattern. Due to their geometrical complexity, multiple configurations of these tessellations were printed from a rubber-like material using an inkjet printer with two different thicknesses (2 and 4 mm), and their ability to absorb impact energy was compared to an unpatterned inkjet-printed sheet. In addition, the effect of multi-sheets stacking was also tested. Due to the tailored structure, the impact testing showed that the single-layer sheets were more effective at absorbing impact loads, and experience less deformation, than their two-layer counterparts. The 4 mm thick tessellated patterns were most effective at absorbing impact loads; all three thick patterns measured about 40% lower impact forces transferred to the base of the samples compared to the unpatterned counterparts.

Charpy impact energy absorption of 3D printed continuous Kevlar reinforced composites

2021 ◽  
pp. 002199832098559
Author(s):  
Dakota R Hetrick ◽  
Seyed Hamid Reza Sanei ◽  
Omar Ashour ◽  
Charles E Bakis
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Charpy Impact ◽  
Impact Testing ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Continuous Fiber ◽  
Fused Deposition ◽  
3D Printed ◽  
The Impact

Additive manufacturing (AM) has been used widely to produce three-dimensional (3D) parts from computer-aided design (CAD) software. Traditional Fused Deposition Modeling (FDM) 3D printed polymer parts lack the necessary strength to be used for functional parts in service. The potential of printing continuous fiber reinforced composites has resulted in parts with better mechanical properties and enhanced performance. Very few studies have investigated the impact energy absorption of continuous fiber reinforced 3 D printed composites. The purpose of this work is to investigate the effect of different fiber patterns (unidirectional versus concentric), different stacking patterns (consolidated versus alternating layers), and fiber orientations (0°, 90°, 45°) on the impact energy absorption of 3 D printed continuous Kevlar fiber reinforced Onyx composites. Charpy impact testing was used to determine the impact energy absorption of the specimens. It was concluded that alternating the fiber and matrix layers as opposed to consolidating all the fiber layers in the center of the specimen results in lower impact energy absorption. Additionally, the specimens with unidirectional 90° fiber orientation had the lowest impact energy absorption among the specimens with alternating stacking pattern and those with consolidated [Formula: see text]45° angle-ply fiber orientations had the highest impact energy absorption.

scholarly journals Evaluation of Microstructure and Impact Toughness of Shielded Metal Arc Dissimilar Weldments of High Strength Low Alloy Steel and Austenitic Stainless Steel

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Misbahu A Hayatu ◽  
Emmanuel T Dauda ◽  
Ola Aponbiede ◽  
Kamilu A Bello ◽  
Umma Abdullahi
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Toughness ◽  
Impact Energy ◽  
High Strength ◽  
Impact Testing ◽  
Welding Parameters ◽  
Dissimilar Weld ◽  
Weld Joints ◽  
The Impact

There is a growing interest for novel materials of dissimilar metals due to higher requirements needed for some critical engineering applications. In this research, different dissimilar weld joints of high strength low alloy (HSLA) and 316 austenitic stainless steel grades were successfully produced using shielded metal arc welding (SMAW) process with 316L-16 and E7018 electrodes. Five variations of welding currents were employed within the specified range of each electrode. Other welding parameters such as heat inputs, welding speeds, weld sizes, arc voltages and time of welding were also varied. Specimens for different weld joint samples were subjected to microstructural studies using optical and scanning electron microscopes. The impact toughness test was also conducted on the samples using Izod impact testing machine. The analysis of the weld microstructures indicated the presence of type A and AF solidification patterns of austenitic stainless steels. The results further showed that the weld joints consolidated with E7018 electrode presented comparatively superior impact energy to the weldments fabricated by 316L-16 electrode. The optimum impact energy of E7018-weld joints (51J) was attained at higher welding heat inputs while that of 316L-16-weld joints (35J) was achieved at lower welding heat inputs, which are necessary requirements for the two electrodes used in the experiment. Hence, the dissimilar weld joints investigated could meet requirement for engineering application in offshore and other critical environments.Keywords—Dissimilar metal weld, heat input, impact toughness, microstructures

Phenomenological Modeling of Carpeted Surface for Drop Simulation of Portable Electronics

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Abhi Sirimamilla ◽  
Hua Ye ◽  
Yinan Wu
Keyword(s):  
Mechanical Response ◽  
Viscoelastic Model ◽  
Single Layer ◽  
Material Model ◽  
Impact Testing ◽  
Consumer Electronics ◽  
Model Parameters ◽  
Portable Devices ◽  
Impact Surface ◽  
The Impact

Using finite element (FE) analysis to simulate drop impact is widely adopted by the consumer electronics industry in the design process of portable devices. Most of such simulations model impact surface as a rigid or simple elastic surface. While this approach is valid for many common hard surfaces such as wood, tile, or concrete, it often does not provide a realistic risk assessment if the impact surface is a soft surface such as carpet. This paper describes a methodology to create a material model for carpeted impact surface that is suited for FE drop simulation. A multilayer hyperelastic–viscoelastic material model is used to model the mechanical response of the carpet under mechanical impact. Quasi-static and impact testing on the industrial carpet were performed to calibrate the model parameters with the help of optimization. Validation of the model was done by comparing the simulation predictions with measurements from the impact tests performed at different heights. Much better correlation between experimental measurements and simulation predictions were observed when using the multilayer hyper-viscoelastic model for carpet than using a single layer homogenous model. This approach can provide a better estimate and a more accurate representation for device drop risk on carpeted surfaces for design and development of portable products. The methodology can also be used to derive material models for other similar impact surfaces.

Control of Large-Scale Impacts by Designed Structural Damping

2005 ◽  
Author(s):  
Jan Wigaard ◽  
Christopher Hoen ◽  
Sverre Haver
Keyword(s):  
Impact Energy ◽  
Large Scale ◽  
Permanent Deformation ◽  
Energy Levels ◽  
Attractive Alternative ◽  
Safety Level ◽  
Shock Absorbers ◽  
Impact Forces ◽  
Multi Body ◽  
The Impact

Modification of deep-water floaters often involves module installation using a floating crane vessel. The impact forces caused by relative motions between the floating vessels represent a major challenge during set down on the floater deck due to the large inherent variability of these forces. Traditionally the difficulties in predicting impact forces during module installation have been overcome by the use of experienced based rules of thumb rather than accurate simulations and calculations. One has to some degree relied on the indeed present but un-quantifiable effect of human intelligence of the operation supervisor. Traditionally the impact forces are taken either by elastic deformation of the module itself and/or the installation guides or by permanent deformation of intermediate structural elements through e.g. plastic yielding of ductile metal members or crushing of wood members. Designing the module and the guides to be able to take the entire probable range of impact forces is difficult due to the inherent contradiction between wanted flexibility and required strength. The large uncertainties of the impact energy imply that it is difficult to design these intermediate elements to cover all possible impact energy levels. Furthermore, these elements cannot be applied in cases where repeated impacts may occur. An attractive alternative to the traditional solutions is application of industrial shock absorbers. The performance of these is predictable and they can be designed to cover the estimated range of impact energy. This paper will present a more precise and consistent design and analyses methodology that gives a more accurate measure on the reliability of the operation in accordance with code requirements. The paper will show application of industrial shock absorbers as an alternative to traditional solutions for impact handling during offshore module installation to floating vessels, illustrated with experience gained by the installation of two modules on the Visund Semi. Results from multi-body simulations and model tests comparing traditional methods with the proposed solution will be given. The significant benefits obtained with respect to increased operational performance, reduced acceleration loads on the installed equipment, the increased predictability of the operation, and the consistent safety level in accordance with code requirements, will be highlighted. The possibility to apply designed damping for other offshore applications like dropped object protection etc, is also discussed.

Impact compression behaviors of high-capacity long piles

2010 ◽  
Vol 47 (12) ◽  
pp. 1335-1350 ◽  
Author(s):  
Arthur K.O. So ◽  
Charles W.W. Ng
Keyword(s):  
Energy Transfer ◽  
Impact Velocity ◽  
Stress Wave ◽  
Impact Energy ◽  
High Capacity ◽  
Measured Data ◽  
Impact Compression ◽  
Impact Forces ◽  
The Impact ◽  
Pile Length

The Hiley formula underestimates driving resistance of long piles. Methods using affected pile length have been suggested, but have been found to be inapplicable for high-capacity piles. The impact compression behaviors of about 4700 high-capacity H-piles that were 14–80 m long at final set were studied. Measured data revealed that maximum impact forces are very scattered, but their means are independent of the hammer type, ram weight, ram drop, impact velocity, and pile length. Maximum impact compression of pile and affected pile length exist in both long and short piles. The affected pile length in turn is significant to the blow efficiency, hammer constant, and energy transfer ratio. This length is governed by the impact momentum and impact energy, and can be estimated by an energy-based equation. If the affected pile length determined by this equation is substituted into the Hiley formula to back-analyze the driving resistance, predictability of the driving formula can be improved by about 8%. This improvement is significant enough to reduce the number of hammer blows required at very hard driving conditions and reduce pile damage. Furthermore, this proposed equation is simple to use in the field and is more economical compared with stress-wave monitoring techniques.

scholarly journals Hydroelasticity effects on water-structure impacts

2020 ◽  
Vol 61 (9) ◽  
Author(s):  
T. Mai ◽  
C. Mai ◽  
A. Raby ◽  
D. M. Greaves
Keyword(s):  
Vertical Wall ◽  
Water Structure ◽  
Rigid Wall ◽  
Total Force ◽  
Impact Loads ◽  
Wave Impact ◽  
Impact Forces ◽  
Elastic Wall ◽  
Vertical Walls ◽  
The Impact

Abstract Local and global loadings, which may cause the local damage and/or global failure and collapse of offshore structures and ships, are experimentally investigated in this study. The research question is how the elasticity of the structural section affects loading during severe environmental conditions. Two different experiments were undertaken in this study to try to answer this question: (i) vertical slamming impacts of a square flat plate, which represents a plate section of the bottom or bow of a ship structure, onto water surface with zero degree deadrise angle; (ii) wave impacts on a truncated vertical wall in water, where the wall represents a plate section of a hull. The plate and wall are constructed such that they can be either rigid or elastic by virtue of a specially designed spring system. The experiments were carried out in the University of Plymouth’s COAST Laboratory. For the cases considered here, elasticity of the impact plate and/or wall has an effect on the slamming and wave impact loads. Here the slamming impact loads (both pressure and force) were considerably reduced for the elastic plate compared to the rigid one, though only at high impact velocities. The total impact force on the elastic wall was found to reduce for the high aeration, flip-through and slightly breaking wave impacts. However, the impact pressure decreased on the elastic wall only under flip-through wave impact. Due to the elasticity of the plates, the impulse of the first positive phase of pressure and force decreases significantly for the vertical slamming impact tests. This significant effect of hydroelasticity is also found for the total force impulse on the vertical wall under wave impacts. Graphic abstract Hydroelasticity effects on water-structure impacts: a impact pressures on dropped plates; b impact forces on dropped plates; c, d, e, f wave impact pressures on the vertical walls; g wave impact forces on the vertical walls; h wave force impulses on the vertical walls: elastic wall 1 vs. rigid wall (filled markers); elastic wall 2 vs. rigid wall (empty markers)

Quantitative Evaluation of Cavitation Erosion

1998 ◽  
Vol 120 (1) ◽  
pp. 179-185 ◽  
Author(s):  
Shuji Hattori ◽  
Hiroyuki Mori ◽  
Tsunenori Okada
Keyword(s):  
Impact Energy ◽  
Cavitation Erosion ◽  
Erosion Resistance ◽  
Impact Load ◽  
Bubble Collapse ◽  
Impact Loads ◽  
Volume Loss ◽  
Developed Pressure ◽  
Cavitation Erosion Resistance ◽  
The Impact

In order to evaluate the quantitative cavitation-erosion resistance of materials, a pressure-detector-installed specimen was developed, which can measure both the impact load produced by cavitation bubble collapse and the volume loss simultaneously. Test specimens (pressure-detection rod) used were nine kinds of metals and were exposed to vibratory cavitation. A linear relation was obtained for all materials between the accumulated impact energy ∑Fi2 calculated from the distribution of impact loads and the volume loss, independent of test conditions. Impact energy accumulated during the incubation period and the energy for a unit material removal in steady-state period were obtained from the relation. These values are very Important concerning quantitative erosion resistance evaluation. That is, when the distribution of impact loads is acquired for different cavitation conditions, the volume loss can be estimated. This idea was applied to the venturi cavitation erosion. The experimental results for venturi test corresponds well with the prediction using these impact energy values. It was concluded that the quantitative impact energy values of materials can be determined independent of the apparatus and the test condition by using the newly developed pressure-detector-installed specimen.

Impact Performance of ZnAl27Cu2.5MgMn Alloy from Room Temperature to 250°C

2014 ◽  
Vol 915-916 ◽  
pp. 597-601
Author(s):  
Ming Long Kang ◽  
Wu Hu ◽  
Jian Min Zeng
Keyword(s):  
Impact Toughness ◽  
Impact Energy ◽  
Room Temperature ◽  
Impact Testing ◽  
Impact Behavior ◽  
Impact Performance ◽  
Temperature Impact ◽  
Spectrum Curve ◽  
The Impact ◽  
Pendulum Impact

The impact performance of ZnAl27Cu2.5MgMn alloy from room Temperature to 2500 °C has been investigated by pendulum impact testing. The surface morphology of impact fracture is observed by scan electron microscope (SEM). The results indicate that impact energy of the alloy decreases as the temperature increases when the temperatures are lower than 100°C. Between 100°C and 200°C, impact energy increases as the temperature increases. And when the temperature exceeds 250°C, impact energy decreases dramatically. Impact energy gets to the maximum at room temperature. Impact behavior of the alloy can be evaluated by the width of impact spectrum curve. The wider the peak of impact spectrum curve, the higher the impact toughness. Whereas impact toughness is worse if peak is narrow.

Experimental and numerical behaviors of GFRP laminates under low velocity impact

2020 ◽  
Vol 54 (21) ◽  
pp. 2999-3007
Author(s):  
Hüseyin E Yalkın ◽  
Ramazan Karakuzu ◽  
Tuba Alpyıldız
Keyword(s):  
Contact Force ◽  
Impact Energy ◽  
Damage Mechanics ◽  
Matrix Material ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Wide Range ◽  
The Impact

The aim of the study is to investigate the behavior of laminated composites under low velocity impact both experimentally and numerically. With this aim, the effects of wide range impact energy values between 10 J and 60 J were evaluated experimentally and numerically for the laminate of [±45/(0/90)2]S oriented unidirectional E-glass as reinforcing material and epoxy resin for matrix material. Different impactor velocities were used to maintain the impact energy values and experimental impact tests were generated with drop weight impact testing machine at room temperature. Numerical simulations were performed using LS-DYNA finite element analysis software with a continuum damage mechanics-based material model MAT058. Contact force between impactor and laminate, and transverse deflection at the center of laminate results were obtained as a function of time and used to plot contact force–time curves, contact force–deflection curves and absorbed energy-impact energy curves. Also, delamination area was examined. Finally, numerical results were compared with experimental results and a good correlation between them was observed.

Dynamic Analysis of Large Specialty Glass Panels Under Ball Drop Impact — Numerical Modeling and Measurements

2012 ◽  
Author(s):  
Satish C. Chaparala ◽  
Praveen R. Samala ◽  
Joshua M. Jacobs ◽  
Jonathan D. Pesansky
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Energy ◽  
Consumer Electronics ◽  
Impact Loads ◽  
Cover Glass ◽  
Element Analysis ◽  
Glass Panels ◽  
Alumino Silicate ◽  
The Impact

Response of brittle plate-like structures to impact loads (suddenly applied loads) has been the subject of many research studies. Specifically, glass used in various household, consumer electronics applications can be subjected to different kinds of impact loads. An ion-exchanged alumino-silicate glass developed by Corning Incorporated, also called Corning® Gorilla® Glass is used as cover glass for flat-panel televisions. One of the reliability tests that may be required for this application is that a steel ball of certain diameter is dropped from certain height at different locations on the glass panel mounted onto a frame. The requirement is that the glass should survive 2 J of impact energy at the center of the glass and 0.5 J of impact energy at the edges. These reliability requirements could change depending on the application and the customer. In this study, finite element analysis is carried out to understand the impact response of such glass panels. Experiments are conducted using strain gauges to measure the panel response at the center of glass with impacts up to 3.3 J. Finite element analysis results are then validated by comparing the predicted strain response with those of measurements.

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