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.

Effect of Critical Void Volume Fraction fF on Results of Ductile Fracture Simulation for S235JR Steel under Multi-Axial Stress States

2014 ◽  
Vol 598 ◽  
pp. 113-118 ◽  
Author(s):  
Paweł Grzegorz Kossakowski ◽  
Wiktor Wciślik
Keyword(s):  
Volume Fraction ◽  
Axial Stress ◽  
Material Model ◽  
Model Parameters ◽  
Material Microstructure ◽  
Fracture Simulation ◽  
Critical Volume Fraction ◽  
Stress States ◽  
The Impact ◽  
Critical Void

The article describes an example of the GTN material model parameters determination and application. The main objective of the study was to determine experimentally the value of the critical volume fraction of voids fFfor S235JR steel and to assess the impact of this parameter on the numerical force-elongation curve under the multi-axial stress state. Value of fFwas obtained by the quantitative analysis of the material microstructure at fracture surfaces. For a sake of comparison, two other values of fF, described in the literature, were also used in numerical simulations.

scholarly journals NUMERICAL MODELLING OF BIRD STRIKE ON A ROTATING ENGINE BLADES BASED ON VARIATIONS OF POROSITY DENSITY

2022 ◽  
Vol 23 (1) ◽  
pp. 412-423
Author(s):  
Sharis-Shazzali Shahimi ◽  
Nur Azam Abdullah ◽  
Ameen Topa ◽  
Meftah Hrairi ◽  
Ahmad Faris Ismail
Keyword(s):  
Numerical Modelling ◽  
Structural Integrity ◽  
Constitutive Relations ◽  
Material Model ◽  
Initial Stresses ◽  
Model Parameters ◽  
Bird Strike ◽  
Elastic Plastic ◽  
Engine Blade ◽  
The Impact

A numerical investigation is conducted on a rotating engine blade subjected to a bird strike impact. The bird strike is numerically modelled as a cylindrical gelatine with hemispherical ends to simulate impact on a rotating engine blade. Numerical modelling of a rotating engine blade has shown that bird strikes can severely damage an engine blade, especially as the engine blade rotates, as the rotation causes initial stresses on the root of the engine blade. This paper presents a numerical modelling of the engine blades subjected to bird strike with porosity implemented on the engine blades to investigate further damage assessment due to this porosity effect. As porosity influences the decibel levels on a propeller blade or engine blade, the damage due to bird strikes can investigate the compromise this effect has on the structural integrity of the engine blades. This paper utilizes a bird strike simulation through an LS-Dyna Pre-post software. The numerical constitutive relations are keyed into the keyword manager where the bird’s SPH density, a 10 ms simulation time, and bird velocity of 100 m/s are all set. The blade rotates counter-clockwise at 200 rad/s with a tetrahedron mesh. The porous regions or voids along the blade are featured as 5 mm diameter voids, each spaced 5 mm apart. The bird is modelled as an Elastic-Plastic-Hydrodynamic material model to analyze the bird’s fluid behavior through a polynomial equation of state. To simulate the fluid structure interaction, the blade is modelled with Johnson-Cook Material model parameters of aluminium where the damage of the impact can be observed. The observations presented are compared to previous study of a bird strike impact on non-porous engine blades. ABSTRAK: Penyelidikan berangka telah dijalankan ke atas bilah enjin berputar tertakluk kepada impak pelanggaran burung. Pelanggaran burung tersebut telah dimodelkan secara berangka sebagai silinder gelatin dengan hujungnya berbentuk hemisfera demi mensimulasikan impaknya ke atas bilah enjin yang berputar. Pemodelan berangka bilah-bilah enjin yang berputar tersebut menunjukkan bahawa pelanggaran burung mampu menyebabkan kerosakan teruk terhadap bilah enjin terutamanya apabila bilah enjin sedang berputar oleh sebab putaran menghasilkan tekanan asal di pangkal bilah enjin. Kajian ini mengetengahkan pemodelan berangka ke atas bilah-bilah enjin tertakluk kepada pelanggaran burung terhadap bilah-bilah enjin yg mempunyai keliangan demi menyelidik dan menilai kerosakan kesan daripada keliangan tersebut. Keliangan juga mempengaruhi tahap-tahap desibel ke atas bilah kipas ataupun bilah enjin, kerosakan hasil serangan burung boleh menterjemah tahap ketahanan struktur integriti bagi bilah-bilah enjin tersebut. Penyelidikan ini mengguna pakai perisian “LS-Dyna Pre-post” untuk simulasi pelanggaran burung. Hubungan konstitutif berangka telah dimasukkan sebagai kata kunci di mana ketumpatan SPH burung, masa simulasi 10ms, dan halaju burung ditetapkan kepada 100 m/s. Bilah tersebut berputar pada 200 rad/s arah lawan jam dengan jejaring tetrahedron. Kawasan berliang atau kosong di sepanjang bilah ditetapkan diameternya kepada 5 mm, dan dijarakkan 5 mm di antara satu sama lain. Burung pula dimodelkan sebagai material “Elastic-Plastic-Hydrodynamic” untuk mengkaji sifat bendalir burung melalui persamaan polinomial. Demi mensimulasi interaksi struktur bendalir, bilah tersebut dimodelkan sebagai parameter aluminium material “Johnson Cook” di mana kerosakan daripada impak tersebut dapat diteliti. Penelitian-penelitian tersebut dibandingkan dengan kajian terdahulu ke atas serangan burung terhadap bilah-bilah enjin tidak berliang.

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.

Advanced finite-element modelling of a 32-panel soccer ball

2007 ◽  
Vol 221 (11) ◽  
pp. 1309-1319 ◽  
Author(s):  
D S Price ◽  
R Jones ◽  
A R Harland
Keyword(s):  
Finite Element ◽  
Polyester Fibre ◽  
Material Model ◽  
Element Model ◽  
Impact Testing ◽  
Material Anisotropy ◽  
Soccer Ball ◽  
Impact Characteristics ◽  
The Impact ◽  
Kinetic Energy Loss

The current paper details the development of a finite-element model of a manually stitched, textile reinforced 32-panel soccer ball used in elite competition. The model included material anisotropy, a stiffer region representative of the polyester fibre based stitching, and a latex bladder membrane which was pressurized through inflation. A stiffness proportional damping coefficient was included within the material model to describe kinetic energy loss characteristics. The model was validated through experimental impact testing at speeds representative of play. It was found that the combined effects of material anisotropy, panel stitching, and panel configuration had a profound effect on the impact characteristics of the ball.

Impact Test and Error Analysis of N80 Waterproof Casing

2013 ◽  
Vol 816-817 ◽  
pp. 317-321
Author(s):  
Lei Shi ◽  
Wei Ma ◽  
Jian Yan ◽  
Hong Zhang ◽  
Zhi Min Li ◽  
...  
Keyword(s):  
Impact Test ◽  
Sample Selection ◽  
Testing Machine ◽  
Impact Testing ◽  
Impact Surface ◽  
Measurement Results ◽  
Causes Of Errors ◽  
Shock Resistance ◽  
The Impact ◽  
Pendulum Impact

N80 waterproof casing is a kind of important equipment in petroleum drilling. In order to analyze the mechanical features of the N80 casing, we used pendulum impact testing machine to test the shock resistance of N80 casing. And we have analyzed and eliminated the errors which may affect the result of the impact test to ensure the reliability. At the same time, it summed up the causes of errors and the methods to avoid and reduce the errors during the pendulum impact test, and analyzed the sample selection method, the chosen of impact surface, the structure as well as the temperature influence, shape and other factors which influenced the measurement results.

On the Influence From Hydrodynamic Forces on Speed and Footprint for a Falling Riser

2004 ◽  
Author(s):  
Vidar Berntsen ◽  
Carl M. Larsen ◽  
Elizabeth Passano ◽  
Nilo De Moura Jorge ◽  
Jose´ Roberto
Keyword(s):  
Material Model ◽  
Model Material ◽  
Model Parameters ◽  
Analysis Method ◽  
Hydrodynamic Load ◽  
Stochastic Variation ◽  
Dynamic Simulations ◽  
Load Model ◽  
Parameter Variations ◽  
The Impact

This paper presents analysis method and key results from dynamic simulations of a drilling riser on 1900 metres water depth after release of upper end. Key results are the geometry of the collapsed riser on the seafloor (footprint) and the impact speed of the riser when hitting the seafloor. The purpose of the study has been to investigate the influence on the results from operational and model parameters such as vessel offset relative to the riser base, current speed, hydrodynamic load model, material model and interaction between the riser and the seafloor. The main conclusion from the study is that most trends from parameter variations are weak and often overshadowed by a more stochastic variation caused by the inherent complexity of the mechanical behaviour during collapse.

Computer simulation of tire rolling resistance using finite element method: Effect of linear and nonlinear viscoelastic models

2018 ◽  
Vol 233 (11) ◽  
pp. 2746-2760 ◽  
Author(s):  
Mehdi Rafei ◽  
Mir Hamid Reza Ghoreishy ◽  
Ghasem Naderi
Keyword(s):  
Research Work ◽  
Viscoelastic Model ◽  
Rolling Resistance ◽  
Experimental Tests ◽  
Material Model ◽  
Resistance Force ◽  
Model Parameters ◽  
Inflation Pressure ◽  
Viscoelastic Models ◽  
Nonlinear Viscoelastic

This research work is devoted to the study of the effect of model parameters and material properties on tire rolling resistance. The main goal of this research is to investigate and clarify the effect of the adopted hyper-viscoelastic material model on tire rolling resistance simulation results. For this purpose, some new approaches were used and current shortcomings were introduced. Computer simulations were carried out using Abaqus standard command line. Linear and parallel rheological framework viscoelastic models were implemented and rolling resistance of a passenger car tire was determined. Different parametric simulations were carried out and the results were compared with rolling resistance data obtained from experimental tests. The results revealed that the calculated rolling resistance force depends on the implemented viscoelastic model. The linear viscoelastic model could not accurately predict the trend of rolling resistance with variation of tire inflation pressure and applied load. On the contrary, parallel rheological framework could cope with this trend. The parallel rheological framework model is more sensitive to inflation pressure. However, the sensitivity of both models to applied vertical load is nearly the same. Although cornering simulation is independent of the adopted viscoelastic model, the type of viscoelastic model could affect the footprint contact pressure contour.

scholarly journals Numerical Simulations of Components Produced by Fused Deposition 3D Printing

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4625
Author(s):  
Martina Scapin ◽  
Lorenzo Peroni
Keyword(s):  
Mechanical Properties ◽  
Fused Deposition Modeling ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Transversely Isotropic ◽  
Material Model ◽  
Model Parameters ◽  
Fused Deposition ◽  
Four Point Bending ◽  
Dog Bone

Three-dimensional printing technology using fused deposition modeling processes is becoming more and more widespread thanks to the improvements in the mechanical properties of materials with the addition of short fibers into the polymeric filaments. The final mechanical properties of the printed components depend, not only on the properties of the filament, but also on several printing parameters. The main purpose of this study was the development of a tool for designers to predict the real mechanical properties of printed components by performing finite element analyses. Two different materials (nylon reinforced with glass or carbon fibers) were investigated. The experimental identification of the elastic material model parameters was performed by testing printed fully filled dog bone specimens in two different directions. The obtained parameters were used in numerical analyses to predict the mechanical response of simple structures. Blocks of 20 mm × 20 mm × 160 mm were printed in four different percentages of a triangular infill pattern. Experimental and numerical four-point bending tests were performed, and the results were compared in terms of load versus curvature. The analysis of the results demonstrated that the purely elastic transversely isotropic material model is adequate for predicting behavior, at least before nonlinearities occur.

Projectile Impact Testing Aluminum Corrugated Core Composite Sandwiches Using Aluminum Corrugated Projectiles: Experimental and Numerical Investigation

2018 ◽  
Vol 910 ◽  
pp. 102-108
Author(s):  
Kutlay Odaci ◽  
Cenk Kılıçaslan ◽  
Alper Taşdemirci ◽  
Athanasios G. Mamalis ◽  
Mustafa Güden
Keyword(s):  
Impact Test ◽  
Composite Plates ◽  
Material Model ◽  
Impact Testing ◽  
Model Parameters ◽  
Projectile Impact ◽  
Composite Sandwich ◽  
Test Models ◽  
Polyester Composite ◽  
The Face

E-glass/polyester composite plates and 1050 H14 aluminum trapezoidal corrugated core composite sandwich plates were projectile impact tested using 1050 H14 aluminum trapezoidal fin corrugated projectiles with and without face sheets. The projectile impact tests were simulated in LS-DYNA. The MAT_162 material model parameters of the composite were determined and then optimized by the quasi-static and high strain rate tests. Non-centered projectile impact test models were validated by the experimental and numerical back face displacements of the impacted plates. Then, the centered projectile impact test models were developed and the resultant plate displacements were compared with those of the TNT mass equal Conwep simulations. The projectiles with face sheets induced similar displacement with the Conwep blast simulation, while the projectiles without face sheets underestimated the Conwep displacements, which was attributed to more uniform pressure distribution with the use of the face sheets on the test plates.

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