Using Microplane Material Model for Concrete in Soft Missile Impact Analysis

2010 ◽  
Author(s):  
Jukka Ka¨hko¨nen ◽  
Pentti Varpasuo
Keyword(s):  
Numerical Integration ◽  
Impact Analysis ◽  
Constitutive Relations ◽  
Material Model ◽  
Medium Size ◽  
Test Case ◽  
Nonlinear Phenomena ◽  
Integration Formulas ◽  
The Impact ◽  
Concrete Model

The paper describes basis of a microplane concrete material model which was implemented in a commercial FE -code using user subroutine interface. The material model is called M4. The motivation for this implementation was a need for a concrete model which would perform well in a soft missile impact analysis. Numerical integration over the surface of a unit sphere is crucial to microplane material models. We tested our microplane implementation using several numerical integration formulas presented in literature. The two fairly simple test cases described in this paper revealed clearly the numerical anisotropy induced by the integration formulations. The impact problem was a medium size, medium velocity soft missile impact test case from an international research program. We compared our implementation of M4 model to a tensorial based damage plasticity concrete model and found out that the results were almost identical. However, the numerical results did not agree well with the measurements in this test case. We concluded this disagreement might be consequence of nonlinear phenomena beyond material constitutive relations.

Material Modeling of Concrete for the Numerical Simulation of Steel Plate Reinforced Concrete Panels Subjected to Impacting Loading

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Huiyun Li ◽  
Guangyu Shi
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Steel Plate ◽  
Material Model ◽  
Tensile Failure ◽  
Scale Model ◽  
Flow Rule ◽  
Plastic Damage ◽  
The Impact ◽  
Concrete Model

The steel plate reinforced concrete (SC) walls and roofs are effective protective structures in nuclear power plants against aircraft attacks. The mechanical behavior of the concrete in SC panels is very complicated when SC panels are under the action of impacting loading. This paper presents a dynamic material model for concrete subjected to high-velocity impact, in which pressure hardening, strain rate effect, plastic damage, and tensile failure are taken into account. The loading surface of the concrete undergoing plastic deformation is defined based on the extended Drucker–Prager strength criterion and the Johnson–Cook material model. The associated plastic flow rule is utilized to evaluate plastic strains. Two damage parameters are introduced to characterize, respectively, the plastic damage and tensile failure of concrete. The proposed concrete model is implemented into the transient nonlinear dynamic analysis code ls-dyna. The reliability and accuracy of the present concrete material model are verified by the numerical simulations of standard compression and tension tests with different confining pressures and strain rates. The numerical simulation of the impact test of a 1/7.5-scale model of an aircraft penetrating into a half steel plate reinforced concrete (HSC) panel is carried out by using ls-dyna with the present concrete model. The resulting damage pattern of concrete slab and the predicted deformation of steel plate in the HSC panel are in good agreement with the experimental results. The numerical results illustrate that the proposed concrete model is capable of properly charactering the tensile damage and failure of concrete.

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.

scholarly journals CRITICAL COMPONENTS IDENTIFICATION USING MUTATION BASED COMPONENTS IMPACT ANALYSIS

2014 ◽  
pp. 58-67
Author(s):  
D. JEYAMALA ◽  
K. SABARI NATHAN ◽  
A. JALILA ◽  
S. BALAMURUGAN
Keyword(s):  
Impact Analysis ◽  
Research Work ◽  
Test Case ◽  
Automated Software Testing ◽  
Testing Framework ◽  
Mutation Operators ◽  
Mutation Score ◽  
Critical Components ◽  
Automated Software ◽  
The Impact

High quality software can be obtained by means of resolving the complexity of the software. According to Pareto principle, 20% of components lead to 80% of the problems [1]. So, we need to identify those 20% of the components during testing. Therefore, this research work suggested an automated software testing framework to identify critical components using mutant based dynamic impact analysis for Software under Test (SUT). Mutants are automatically generated by injecting faults in the components using Offutt mutation operators and they are utilised to identify their impact level over other components of the system. The generated mutants and original program are executed using the suite of test cases, based on the conclusion of both the results, the mutation score is assessed and furthermore it is utilised as the test case adequacy criterion to recognize the impact level of it over the other components of a system. The outcome of this innovative approach is a testing tool entitled as JImpact Analyzer that automates the entire task and has generates miscellaneous graphs for visualization purpose.

scholarly journals Identification of thermal material parameters for thermo-mechanically coupled material models

Meccanica ◽  
2021 ◽  
Vol 56 (2) ◽  
pp. 393-416
Author(s):  
L. Rose ◽  
A. Menzel
Keyword(s):  
Evolution Equations ◽  
Constitutive Relations ◽  
Material Model ◽  
Basic Material ◽  
Dissipated Energy ◽  
Model Formulation ◽  
Material Models ◽  
Material Parameters ◽  
Simple Tension ◽  
The Impact

AbstractThe possibility of accurately identifying thermal material parameters on the basis of a simple tension test is presented, using a parameter identification framework for thermo-mechanically coupled material models on the basis of full field displacement and temperature field measurements. Main objective is to show the impact of the material model formulation on the results of such an identification with respect to accuracy and uniqueness of the result. To do so, and as a proof of concept, the data of two different experiments is used. One experiment including cooling of the specimen, due to ambient temperature, and one without specimen cooling. The main constitutive relations of two basic material models are summarised (associated and non-associated plasticity), whereas both models are extended so as to introduce an additional material parameter for the thermodynamically consistent scaling of dissipated energy. The chosen models are subjected to two parameter identifications each, using the data of either experiment and focusing on the determination of thermal material parameters. The influence of the predicted dissipated energy of the models on the identification process is investigated showing that a specific material model formulation must be chosen carefully. The material model with associated evolution equations used within this work does neither allow a unique identification result, nor is any of the solutions for the underlying material parameters close to literature values. In contrast to that, a stable, that is locally unique, re-identification of the literature values is possible for the boundary problem at hand if the model with non-associated evolution equation is used and if cooling is included in the experimental data.

Experimental Methods for Dynamic Stress Analysis in Viscoelastic Materials

1965 ◽  
Vol 32 (3) ◽  
pp. 598-606 ◽  
Author(s):  
I. M. Daniel
Keyword(s):  
Stress Analysis ◽  
Numerical Integration ◽  
Dynamic Stress ◽  
Dynamic Properties ◽  
Constitutive Relations ◽  
Relaxation Modulus ◽  
Experimental Methods ◽  
Viscoelastic Materials ◽  
Dynamic Stress Analysis ◽  
The Impact

This paper deals with experimental methods of dynamic stress analysis in viscoelastic materials. Plasticized polyvinyl chloride is used as the model material. Dynamic properties, both mechanical and optical, in the form of a complex modulus and a stress fringe value as functions of frequency are determined by means of sinusoidal oscillation tests. These are converted into a relaxation modulus and a stress fringe value as functions of time. Two approaches are discussed. In the first one, measured strains in the model and the material relaxation modulus are used for the computation of stresses by numerical integration of the integral constitutive relations of viscoelasticity. In the other approach, birefringent measurements in the model and the stress fringe value of the material are used for the computation of the principal stress difference by numerical integration of the integral stress-optic relation. The application of these methods is demonstrated in the cases of a strut and a plate subjected to the impact of a falling weight. Results obtained independently by the two methods are in satisfactory agreement.

Software Change Impact Analysis

2015 ◽  
Vol 5 (2) ◽  
pp. 44-55
Author(s):  
Chetna Gupta ◽  
Varun Gupta
Keyword(s):  
Impact Analysis ◽  
Software Engineer ◽  
Maintenance Cost ◽  
Test Case ◽  
Test Cases ◽  
Change Impact Analysis ◽  
Call Graph ◽  
Regression Test ◽  
Change Impact ◽  
The Impact

This paper presents an approach to prioritize program segments within the impact set computed using functional call graph to assist regression testing for test case prioritization. The presented technique will first categorize the type of impact propagation and then prioritize the impacted segments into higher and lower levels based on propagation categorization. This will help in saving maintenance cost and effort by allocating higher priority to those segments which are impacted more within the impacted set. Thus a software engineer can first run those test cases which cover segments with higher impacted priority to minimize regression test selection.

scholarly journals Costs to Reduce the Human Health Toxicity of Biogas Engine Emissions

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6360
Author(s):  
Alberto Benato ◽  
Alarico Macor
Keyword(s):  
Human Health ◽  
Internal Combustion Engines ◽  
Impact Analysis ◽  
Combustion Engine ◽  
Combustion Process ◽  
Internal Combustion ◽  
Health Impact ◽  
Test Case ◽  
Disability Adjusted Life ◽  
The Impact

The anaerobic digestion of biodegradable substrates and waste is a well-known process that can be used worldwide to produce a renewable fuel called biogas. At the time of writing, the most widespread way of using biogas is its direct usage in combined heat and power internal combustion engines (CHP-ICEs) to generate electricity and heat. However, the combustion process generates emissions, which in turn have an impact on human health. Therefore, there is a need to: (i) measure the ICE emissions (both regulated and unregulated), (ii) compute the impact on human health, (iii) identify the substances with the highest impact and (iv) calculate the avoided damage to human health per Euro of investment in technology able to abate the specific type of pollutant. To this end, the authors conducted an experimental campaign and selected as a test case a 999 kWel biogas internal combustion engine. Then, the collected data, which included both regulated and unregulated emissions, were used to calculate the harmfulness to human health and identify the more impactful compounds. Thus, combining the results of the impact analysis on human health and the outcomes of a market analysis, the avoided damage to human health per Euro of investment in an abatement technology was computed. In this manner, a single parameter, expressed in DALY -1, provided clear information on the costs to reduce each disability-adjusted life year (DALY). The impact analysis on human health, which was performed using the Health Impact Assessment, showed that NOx was the main contributor to damage to human health (approximately 91% of the total), followed by SOx (6.5%), volatile organic compounds (1.4%) and CO (0.7%). Starting from these outcomes, the performed investigation showed that the technology that guarantees the maximum damage reduction per unit of cost is the denitrification system or the oxidizing converter, depending on whether the considered plant is already in-operation or newly built. This is an unexpected conclusion considering that the most impacting emission is the NOx.

The Impact of a Potential Public/Private Initiative on a Defined Region of the South Suburban Chicago Metropolitan Area

2019 ◽  
pp. 14-32
Keyword(s):  
Supply Chain ◽  
Economic Impact ◽  
Impact Analysis ◽  
Census Data ◽  
Economic Benefits ◽  
Local Economy ◽  
Market Area ◽  
State And Local ◽  
The University ◽  
The Impact

The university is considered one of the engines of growth in a local economy or its market area, since its direct contributions consist of 1) employment of faculty and staff, 2) services to students, and supply chain links vendors, all of which define the University’s Market area. Indirect contributions consist of those agents associated with the university in terms of community and civic events. Each of these activities represent economic benefits to their host communities and can be classified as the economic impact a university has on its local economy and whose spatial market area includes each of the above agents. In addition are the critical links to the University, which can be considered part of its Demand and Supply chain. This paper contributes to the field of Public/Private Impact Analysis, which is used to substantiate the social and economic benefits of cooperating for economic resources. We use Census data on Output of Goods and Services, Labor Income on Salaries, Wages and Benefits, Indirect State and Local Taxes, Property Tax Revenue, Population, and Inter-Industry to measure economic impact (Implan, 2016).

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Impact Analysis of the Mechanization Program for Tribal Paddy Farmers of Goa

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
MATHALA JULIET GUPTA ◽  
ASHISH M. PITRE ◽  
SUMATI CHAVAN PANDURNAG ◽  
SALONI SALIL VANJARI
Keyword(s):  
Impact Analysis ◽  
Field Capacity ◽  
Significant Saving ◽  
Manual Methods ◽  
Paddy Farmers ◽  
The Impact ◽  
And Training

This paper assessed the impact of the mechanization of the 8 tribal paddy farmers’ groups of Goa benefited in the year 2011 through the Tribal sub-plan program of ICAR-CCARI through results of surveys conducted in 2012 and 2015. Shift to mechanization among beneficiaries was significant in power tillers (64-100%) but less in power reapers(0-91%). Also significant saving in manpower (Power tillers:33.3% to 60%, power reapers: 33.3% to 83.3%), , time (field capacity increased (power tillers : 41.7% to141%, power reapers :58.1% to 912.8%) and cost(power tillers :44.7% to 59.1%, power reapers : 57.8% to 82.9%) was reportedthrough the use of equipment as compared to desi plough or manual methods of harvesting. Some constraints like lack of access roads and training in use and maintenance of the equipment were reported by the beneficiary farmers.

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