Impact Analysis of Plates Using Quasi-Static Approach

1997 ◽  
Vol 119 (3) ◽  
pp. 376-381 ◽  
Author(s):  
S. Shivaswamy ◽  
H. M. Lankarani
Keyword(s):  
Impact Analysis ◽  
Local Deformation ◽  
Contact Forces ◽  
Stress Wave Propagation ◽  
Rigid Base ◽  
Deformation Model ◽  
Stiff Systems ◽  
Stiff System ◽  
Nonlinear Force ◽  
The Impact

Impact analyses suffer from several practical limitations which limit their application to predict the approximate magnitude of the various phenomena involved. The transient force deformation response of a body subjected to impact can be explained accurately using the stress wave propagation theory. As this approach is complicated, a simpler approach utilizing a quasi-static equilibrium condition can be employed. Nonlinear force-deformation Hertzian relations can be used for the impact analysis. These relations though can not explain the energy dissipation and permanent deformations encountered during the impact. This necessitates independent nonlinear force deformation relations for compression and restitution phases of impact. In this paper, modeling of contact forces during impact on stiff systems (systems which do not undergo gross deformation but experience only local deformation) has been presented. Experiments were conducted on stiff systems to verify the methodology. A plate which is fixed on a rigid base and clamped completely represents a stiff system. Hence experiments were conducted on Aluminum and Steel plates to simulate impact on stiff systems for the verification of the proposed models. The theoretical results matched well with the experimental results. A nonlinear force deformation model with independent relations for compression and restitution phases was found to be a suitable approach to analyze impact problems.

Impact Analysis of Plates Using Quasi-Static Approach

1994 ◽  
Author(s):  
Shashishekar Shivaswamy ◽  
Jianmin Li ◽  
Hamid M. Lankarani
Keyword(s):  
Impact Analysis ◽  
Steel Plates ◽  
Stress Wave Propagation ◽  
Deformation Model ◽  
Static Force ◽  
Non Linear ◽  
Static Approach ◽  
Linear Force ◽  
Impact Problems ◽  
The Impact

Abstract Impact calculations suffer from several practical limitations which limit their application to establishing the approximate magnitude of the various phenomena involved. The transient force deformation response of a body subjected to impact can be explained accurately using stress wave propagation theory. As this approach is very complicated, a simpler quasi-static approach with non-linear force deformation Hertz relations can be employed for impact analysis. However, these relations can not explain the energy absorption and permanent deformations encountered during the impact. This necessitates independent non-linear force-deformation relations for compression and restitution phases of impact. In the present paper, impact tests conducted on Aluminum and Steel plates have been reported. The impact response of the system was compared with the various theoretical quasi-static force models. Considering the assumptions made in the quasi-static force models, the experimental results matched very well with the theoretical results. Non-linear force-deformation model with independent relations for compression and restitution phases was found to be the best approach to analyze impact problems. The value of the index in the non-linear force-deformation relations was found to be approximately 1.71 and 1.78 for Aluminum and Steel respectively. The values of impact parameters for a given material were found to depend on impact velocity.

Dynamics of High Speed Roller Chain Drives

1995 ◽  
Author(s):  
Peter Fritz ◽  
Friedrich Pfeiffer
Keyword(s):  
High Speed ◽  
Contact Forces ◽  
System Structure ◽  
Unilateral Constraints ◽  
Roller Chain ◽  
Contact Configuration ◽  
Nonlinear Force ◽  
A Chain ◽  
The Impact ◽  
Chain Drives

Abstract This paper deals with roller chain drives applied in combustion engines. In order to find characteristics for an optimal design, all components of a chain drive are taken into account. For a detailed analysis of the chain strand vibrations and the contact configurations each chain link, sprocket and guide is treated as a separate body. A nonlinear force element describes the joint forces, including elasticity, damping, backlash and oil-displacement. To determine real contact forces between a link and a sprocket or a guide, the exact contour and the mutual dependence of the contacts are considered. The impact of one link may influence the other links in such a manner that their contact configuration may change. In the mechanical model these contacts are represented by unilateral constraints. Applying the formulation of the linear complementarities including additional inequality conditions, the determination of a valid contact configuration after a change in the system structure is simplified.

scholarly journals Interactive Multimode Blade Impact Analysis

1982 ◽  
Vol 104 (2) ◽  
pp. 286-295
Author(s):  
A. Alexander
Keyword(s):  
Computer Program ◽  
Impact Analysis ◽  
Impact Resistance ◽  
Local Deformation ◽  
Mode Shapes ◽  
Turbine Engine ◽  
Impact Area ◽  
Fan Blade ◽  
Mode Beam ◽  
The Impact

This paper describes the theoretical methodology used in developing an analysis for the response of turbine engine fan blades subjected to soft body (bird) impacts and the computer program that was developed using this methodology as its basis. This computer program is an outgrowth of two programs that were previously developed for the purpose of studying problems of a similar nature (a three-mode beam impact analysis and a multimode beam impact analysis). The present program utilizes an improved missile model that is interactively coupled with blade motion which is more consistent with actual observations. It takes into account local deformation at the impact area, blade camber effects, and the spreading of the impacted missile mass on the blade surface. In addition, it accommodates plate-type mode shapes. The analysis capability in this computer program represents a significant improvement in the development of the methodology for evaluating potential fan blade materials and designs with regard to foreign object impact resistance.

scholarly journals Interactive Multi-Mode Blade Impact Analysis

1981 ◽  
Author(s):  
A. Alexander
Keyword(s):  
Computer Program ◽  
Impact Analysis ◽  
Impact Resistance ◽  
Local Deformation ◽  
Mode Shapes ◽  
Turbine Engine ◽  
Fan Blade ◽  
Mode Beam ◽  
The Impact ◽  
Multi Mode

This paper describes the theoretical methodology used in developing an analysis for the response of turbine engine fan blades subjected to soft body (bird) impacts and the computer program that was developed using this methodology as its basis. This computer program is an outgrowth of two programs that were previously developed for the purpose of studying problems of a similar nature (a three-mode beam impact analysis and a multi-mode beam impact analysis). The present program utilizes an improved missile model that is interactively coupled with blade motion which is more consistent with actual observations. It takes into account local deformation at the impact area, blade camber effects, and the spreading of the impacted missile mass on the blade surface. In addition, it accommodates plate-type mode shapes. The analysis capability in this computer program represents a significant improvement in the development of the methodology for evaluating potential fan blade materials and designs with regard to foreign object impact resistance.

Multiscale Simulations for Impact Load–Induced Vibration: Assessing a Structure's Vulnerability

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Jeongwon Park ◽  
Man Hoi Koo ◽  
Hak-Sung Kim ◽  
Junhong Park
Keyword(s):  
Multiple Scales ◽  
Impact Load ◽  
Local Deformation ◽  
Core Material ◽  
Flexural Wave ◽  
Deformation Model ◽  
Vibration Responses ◽  
Penetration Behavior ◽  
Impact Simulations ◽  
The Impact

Vibration resulting from high-velocity projectiles impacting a structure was simulated at multiple scales. Local impact simulations were performed to predict the material deformation and penetration phenomena at the location of impact. The resulting penetration behavior of a steel panel was analyzed for various projectile velocities, sizes, and panel thicknesses. Three-layer panels with Kevlar as the core material were simulated to understand the effects of structural layering on the reduction of the impact force. The forces acting on the panel in the longitudinal and transverse directions were calculated from the obtained stress distribution in the local deformation model. Using the estimated force input, transient longitudinal and flexural wave propagations were calculated to analyze the radiation of the impact energy along the structural span. Vulnerable positions with high possibilities of damage to crucial components due to impact loading were identified from the resulting vibration responses.

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.

scholarly journals Observing the silent world under COVID-19 with a comprehensive impact analysis based on human mobility

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shaobin Wang ◽  
Yun Tong ◽  
Yupeng Fan ◽  
Haimeng Liu ◽  
Jun Wu ◽  
...  
Keyword(s):  
Impact Analysis ◽  
Human Mobility ◽  
Economic Activities ◽  
Underdeveloped Countries ◽  
Mobility Data ◽  
Long Run ◽  
Level Of Economic Development ◽  
Human World ◽  
Dynamic Relationships ◽  
The Impact

AbstractSince spring 2020, the human world seems to be exceptionally silent due to mobility reduction caused by the COVID-19 pandemic. To better measure the real-time decline of human mobility and changes in socio-economic activities in a timely manner, we constructed a silent index (SI) based on Google’s mobility data. We systematically investigated the relations between SI, new COVID-19 cases, government policy, and the level of economic development. Results showed a drastic impact of the COVID-19 pandemic on increasing SI. The impact of COVID-19 on human mobility varied significantly by country and place. Bi-directional dynamic relationships between SI and the new COVID-19 cases were detected, with a lagging period of one to two weeks. The travel restriction and social policies could immediately affect SI in one week; however, could not effectively sustain in the long run. SI may reflect the disturbing impact of disasters or catastrophic events on the activities related to the global or national economy. Underdeveloped countries are more affected by the COVID-19 pandemic.

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