The Wear Process Between Normally Impacting Elastic Bodies

1974 ◽  
Vol 96 (4) ◽  
pp. 595-604 ◽  
Author(s):  
P. A. Engel ◽  
R. G. Bayer
Keyword(s):  
Peak Strain ◽  
Impact Wear ◽  
Axially Symmetric ◽  
Surface Geometry ◽  
Normal Impact ◽  
Wear Process ◽  
Surface Fatigue ◽  
Elastic Bodies ◽  
Symmetric Configuration ◽  
The Impact

The wear process between two elastic bodies, repeatedly impacting in an axially symmetric configuration is investigated analytically and experimentally. The mechanism initiating wear is that of surface fatigue, and the paper aims to explain the geometric process of wear formation beyond the “zero wear limit.” In doing so, an engineering, predictive model is sought, whereby the depth of a worn crater is related to the stresses arising during impact and to the number of loading cycles on the specimen. Four major accomplishments are embodied in the paper: (1) the quasi-static analysis of impact on a medium of nonuniform (cratered) surface geometry, (2) a heuristic derivation of the optimum wearpath, (3) derivation of the partial differential equation of normal impact wear, and (4) computation of the impact wear process for two discrete impact wear configurations and comparison of experimental work with the analytical results. The resulting conclusion is that impact wear proceeds at continuously varying curvature until the soft body conforms to the shape of the hard indenter. By equating the hysteretic wear energy with a fraction of the peak strain energy, quantitative wear history predictions are made for discrete geometries, such as a hard sphere impacting against a soft plane. Some experimental results are given between steel and aluminum specimens, confirming the analytical predictions.

THE IMPACT OF ELASTIC BODIES

1971 ◽  
pp. 266-288
Author(s):  
C. PLUMPTON ◽  
W.A. TOMKYS
Keyword(s):  
Elastic Bodies ◽  
The Impact

Interaction of external head impact parameters on region and volume of strain for collisions in sport

2018 ◽  
Vol 233 (2) ◽  
pp. 258-267 ◽  
Author(s):  
R Anna Oeur ◽  
Michael D Gilchrist ◽  
Thomas Blaine Hoshizaki
Keyword(s):  
Brain Injuries ◽  
Element Model ◽  
Brain Regions ◽  
Peak Strain ◽  
Centre Of Gravity ◽  
Impact Parameters ◽  
Four Levels ◽  
Set Up ◽  
The Impact ◽  
Strain Responses

Collisions with the head are the primary cause of concussion in contact sports. Head impacts can be further characterized by velocity, striking mass, compliance, and location (direction). The purpose of this study was to describe the interaction effects of these parameters on peak strain in four brain regions and the volume of strain for collision impacts. A pendulum test set-up was used to deliver impacts to an adult Hybrid III headform according to four levels of mass (3, 9, 15, and 21 kg), four velocities (1.5, 3.0, 4.5, and 6.0 m/s), two impact locations (through the centre of gravity and a non-centre of gravity), and three levels of compliance simulating unprotected, helmeted, and well-padded conditions in sport. Headform accelerations were input into a brain finite element model to obtain peak strain in the frontal, temporal, parietal, and occipital lobes and the volume of the brain experiencing 0.10, 0.15, 0.20, and 0.25 strains. Centre-of-gravity impacts created the highest strains (peak and volume) under low compliance and non-centre-of-gravity impacts produced greater strain responses under medium and high compliance conditions. The temporal lobe was the region that consistently displayed the highest peak strains, which may be due to the proximity of the impact locations to this region. Interactions between mass and velocity displayed effects where the 9-kg mass had higher peak and volumes of strain than the 15-kg mass at velocities of 3.0 and 4.5 m/s. This study demonstrates the important role of interacting impact parameters on increasing strain responses that are relevant to the spectrum of diffuse brain injuries, including concussion.

scholarly journals A Method for Evaluating the Impact Wear Behavior of Multilayer TiN/Ti Coating

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 132 ◽  
Author(s):  
Xin Cao ◽  
Weisheng Xu ◽  
Weifeng He
Keyword(s):  
Wear Behavior ◽  
Failure Mechanisms ◽  
High Stress ◽  
Impact Wear ◽  
Maximum Value ◽  
Impact Peak ◽  
Energy Dissipated ◽  
The Impact ◽  
Impact Zones ◽  
Circular Cracks

An energy-controlled cycling impact test was applied to evaluate the impact wear behavior of hard coating. A multilayer TiN/Ti coating with a total thickness of ~10 μm, containing two TiN layers and two Ti layers, with the thickness ratio of these two kinds of the layers being 9:1, was chosen as the research object. The impact velocities were 60, 120, and 180 mm/s, and the impact cycles were 10, 102, 103, and 104, respectively. Damage morphology observation and numerical simulation were used to analyze the failure mechanisms. The results show that the contact time keeps almost constant under different impact velocities and cycles. Impact peak forces remain unchanged with increasing cycles at the same velocity, but they increase linearly with impact velocities, reaching a maximum value of 262.26 N at 180 mm/s. The energy dissipated rate (EDR) increases from 31.58% at 60 mm/s to 35.59% at 180 mm/s, indicating the degenerative toughness. Two impact-wear failure mechanisms are found in impact zones of the coating; these are peeling and circular cracks. Peelings are induced by cycling high-stress gradients in hard layers and interfaces. Circular cracks are caused by cycling tensile stresses in the form of fatigue at the edge of impacted pits.

Designing with pixels: parametric thinking for patterning dynamic building facades

2019 ◽  
Vol 26 (4) ◽  
pp. 668-688
Author(s):  
Zaki Mallasi
Keyword(s):  
Design Thinking ◽  
Real Life ◽  
Digital Design ◽  
Blue Color ◽  
Practical Application ◽  
Surface Geometry ◽  
Content Type ◽  
Building Facade ◽  
Building Facades ◽  
The Impact

Purpose Advances in digital design tools enable exploration and generation of dynamic building facades. However, some processes are formally prescribed and manually driven to only visualize the design concepts. The purpose of this paper is to present a proactive framework for integrating parametric design thinking, paying particular attention to building facade patterning. Design/methodology/approach This work developed the PatternGen© add-on in Autodesk® Revit which utilizes an analytical image data (AID) overlay approach as a data source to dynamically pattern the building facade. The add-on was used to manipulate the placement rules of curtain panels on facade surface geometry. As means of validating this research model, a real-life design project has been chosen to illustrate the practical application of this approach. Feedback and observations from a short end-user questionnaire assessed qualitatively the facade patterning and panelization approach. Findings The proposed merge (or overlay) of AID images can be used as a parametric thinking method rather than just theory to generate and articulate dynamic facade design. The facade panelization responds to an AID that resembles design-performance data (e.g. solar exposure, interior privacy importance and aesthetics). Originality/value This work identifies a form of parametric thinking defined as the expression of geometrical relationships and its configuration dependent on the AID pixel Red Green Blue color source values. In this type of thinking, it explores the impact of the digital process and parametric thinking utility when driven by an AID overlay. The framework highlighted the practical application of AID pixel approach within a digital process to benefit both designers and computational tools developer on emerging design innovations.

Effect of the Fine Recycled Aggregates on the Dynamic Compressive Behavior of Recycled Mortar

2020 ◽  
Vol 991 ◽  
pp. 62-69
Author(s):  
Sallehan Ismail ◽  
Mohamad Asri Abd Hamid ◽  
Zaiton Yaacob
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Energy Absorption ◽  
Specific Energy ◽  
Split Hopkinson Pressure Bar ◽  
Recycled Aggregates ◽  
Fine Aggregate ◽  
Peak Strain ◽  
Specific Energy Absorption ◽  
The Impact

This study aims to investigate the dynamic behavior of recycled mortar under impact loading using a split Hopkinson pressure bar (SHPB). Several mortar mixtures were produced by adding various fine recycled aggregates (FRA) to the mixture in replacement percentages of 0%, 25%, 50%, 75%, and 100% of the natural fine aggregate (NFA). The effects of strain rate on compressive strength and specific energy absorption were obtained. Results show that the dynamic compressive strength and specific energy absorption of recycled mortar are highly strain rate dependent; specifically, they increase nearly linearly with the increase in peak strain rate. However, the compressive strength and specific energy absorption of recycled mortar are generally lower than those of NFA mortar (reference samples) under similar high strain rates. The findings of this research can help researchers and construction practitioners to ascertain the appropriate mix design procedure to optimize the impact strength properties of recycled mortar for protective structural application.

The Impact of Hardened Steel Milling Surface Structure on Mould Service Load

2014 ◽  
Vol 800-801 ◽  
pp. 342-347
Author(s):  
Min Li Zheng ◽  
Jin Hui Xu ◽  
Wei Zhang ◽  
Zhao Xing Zhang ◽  
Tong Wu
Keyword(s):  
Hardened Steel ◽  
Surface Load ◽  
Surface Geometry ◽  
Surface Loading ◽  
Machined Surface ◽  
Geometry Model ◽  
Geometry Structure ◽  
Mould Surface ◽  
Service Load ◽  
The Impact

Mould surface loading state is one of the most important factors which would affect the mould performance in the course of service. According to the established hardened steel milling surface geometry model, a bending forming numerical simulation of hardened steel milling is conducted, the influence law of service process surface load state is analyzed under machined surface geometry structure which is formed by different milling parameters. The research results show: surface load concentrated area is mainly focusing on mould edge transition and fillet in the course of service; the surface geometry structure has an important influence on the mould service load in the course of service, service load more smaller which is more helpful to improve the mould service performance in the course of service.

A Study for Evaluating Local Damage to RC Panels Subjected to Oblique Impact: Part 1 — A Study for Evaluating Local Damage Caused by Oblique Impact of Rigid Projectiles

2017 ◽  
Author(s):  
Yoshimi Ohta ◽  
Akemi Nishida ◽  
Haruji Tsubota ◽  
Yinsheng Li
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Oblique Impact ◽  
Reinforced Concrete Structures ◽  
Local Damage ◽  
Normal Impact ◽  
Impact Tests ◽  
Oblique Impacts ◽  
New Formula ◽  
The Impact

Many empirical formulae have been proposed to evaluate the local damage to reinforced concrete structures caused by the impact of rigid projectiles. Most of these formulae have been derived based on impact tests perpendicular to the target structures. To date, few impact tests oblique to the target structures have been conducted. The purpose of this study is to propose a new formula for evaluating the local damage caused by oblique impacts based on experiments and simulations. The new formula is derived by modifying an empirical formulation for normal impact and the agreement with results of past oblique impact tests is discussed.

Wear behaviors of WC and TiC on co matrix composites under three-body impact abrasive wear condition

2019 ◽  
Vol 71 (7) ◽  
pp. 893-900 ◽  
Author(s):  
Lei Dong ◽  
Xiaoyu Zhang ◽  
Kun Liu ◽  
Xiaojun Liu ◽  
Ruiming Shi ◽  
...  
Keyword(s):  
Wear Rate ◽  
Abrasive Wear ◽  
Impact Energy ◽  
Wear Behavior ◽  
High Impact ◽  
Impact Wear ◽  
High Impact Energy ◽  
Content Type ◽  
Three Body ◽  
The Impact

Purpose The purpose of this paper is to investigate the tribological properties of the WC/TiC-Co substrate under different loading conditions under three impact abrasive wear conditions. Design/methodology/approach The three body collisional wear behavior of Co alloy with WC and TiC at three impact energy was studied from 1 to 3 J. Meanwhile, the microstructure, hardness, phase transformation and wear behavior of these specimens were investigated by scanning electron microscopy, Rockwell hardness (HRV), EDS and impact wear tester. The resulting wear rate was quantified by electronic balance measurements under different pressures. Findings The specific wear rate increases with the increase of the nonlinearity of the impact energy and the increase in the content of WC or TiC. The effect of TiC on wear rate is greater than that of WC, but the hardness is smaller. The wear characteristics of the samples are mainly characterized by three kinds of behavior, such as cutting wear, abrasive wear and strain fatigue wear. The WC-Co with fewer TiC samples suffered heavier abrasive wear than the more TiC samples under both low and high impact energy and underwent fewer strain fatigue wears under high impact energy. Originality/value The experimental results show that the wear resistance of the Co alloy is improved effectively and the excellent impact wear performance is achieved. The results can be used in cutting tools such as coal mine cutting machines or other fields.

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