ENGINEERING METROLOGY FOR PEDESTRIAN FALLS PREVENTION AND PROTECTION : theories to... applications for designing safer shoes and floors

This book explains how to improve the validity, reliability, and repeatability of slip resistance assessments amongst a range of shoes, floors, and environments from an engineering metrology viewpoint―covering theoretical and experimental aspects of slip resistance mechanics and mechanisms. Pedestrian falls resulting from slips or falls are one of the foremost causes of fatal and non-fatal injuries that limit people’s functionality. There have been prolonged efforts globally to identify and understand their main causes and reduce their frequency and severity. This book deals with large volumes of information on tribological characteristics such as friction and wear behaviours of the shoes and floors and their interactive impacts on slip resistance performances. Readers are introduced to theoretical concepts and models and collected evidence on slip resistance properties amongst a range of shoe and floor types and materials under various ambulatory settings. These approaches can be used to develop secure design strategies against fall incidents and provide a great step forward to build safer shoes, floors, and walking/working environments for industries and communities around the world. The book includes many case studies. Preface Background and Motivation Main Aims of This Book Construction of This Book Acknowledgements Contents Glossary Terms, Abbreviations and Acronyms List of Figures List of Tables Part I Engineering Metrology for Falls Safety Assessments 1 Introduction 1.1 Milieus 1.2 Current Hiatuses on Slip Resistance Assessments 1.2.1 Fundamental Issues 1.2.2 Common Mistakes 1.2.3 Practicality of Dry Tests 1.3 Tribology Fundamentals for the Shoe-Floor System 1.3.1 Tribology Concept 1.3.2 A Shoe-Floor Tribology System 1.3.3 Importance of Understanding on Friction Behaviour 1.3.4 Significance of Wear Phenomena 1.3.5 Slip Resistance Measurements 1.4 Validity, Reliability, and Repeatability 1.4.1 Validity 1.4.2 Reliability 1.4.3 Repeatability 1.5 Main Objectives 1.6 Important Messages 1.7 Conclusions 1.8 Precincts of the Current Chapter Study 1.9 Summary References 2 A New Research Challenge on Slip Resistance Measurements 2.1 Milieus 2.2 Significant Questions on COFs 2.2.1 Meaning of a COF 2.2.2 Dilemma of an Average or Mean COF 2.2.3 Limitations of a COF Index or Quantity 2.2.4 Frictional Force 2.3 Surface Analyses 2.3.1 Importance of Surface Analysis 2.3.2 Effects of Surface Roughness on Slip Resistance Properties 2.4 Theory Developments 2.4.1 A Tribological System Between the Shoe and Floor 2.4.2 Primary Aspects of Wear Characteristics 2.5 Suggestion of a Shoe-Floor Tribology Model 2.5.1 Main Hypotheses 2.5.2 Friction Model Development 2.5.3 Contact Zone Measurement 2.5.4 Wear Model 2.6 Conclusions 2.7 Summary References Part II Fundamentals of Tribology 3 Basic Principles of Tribology 3.1 Milieus 3.2 Basics in Tribology 3.2.1 What is Tribology? 3.2.2 Fundamentals of Tribology 3.2.3 Friction Mechanism 3.2.4 Wear Mechanism 3.2.5 Formation of Tribo-Films 3.2.6 Lubrication 3.3 Surface Structures and Measuring Methods 3.3.1 Background 3.3.2 What is a Surface? 3.3.3 Surface Analysis 3.3.4 Techniques for Surface Characterization 3.3.5 Shapes of Solid Surfaces 3.3.6 Surface Metrology Techniques (Surface Profile Probes) 3.4 Surface Natures and Their Contact Mechanisms 3.4.1 Background 3.4.2 Imperative Aspects of Surfaces and Their Contact Mechanism 3.4.3 Basic Theories of Surface Contact 3.5 Geometrical Characteristics of Surface Texture 3.5.1 Introduction 3.5.2 Surface Texture 3.6 Quantifying Surface Structures 3.6.1 Introduction 3.6.2 Measuring Lengths 3.6.3 Reference Line 3.6.4 Traditional Surface Texture Parameters 3.6.5 Statistical Analysis of Surface Profile 3.7 Surface Texture Measurements 3.7.1 Introduction 3.7.2 Surface Profilometry 3.7.3 Laser Scanning Confocal Microscopy 3.8 Conclusions 3.9 Summary References 4 Frictional Behaviours and Mechanisms 4.1 Milieus 4.2 Friction Mechanisms 4.2.1 Introduction 4.2.2 Factors Affecting Friction Force 4.2.3 Dry Friction 4.2.4 Normal Force 4.2.5 Coefficient of Friction 4.2.6 Static Friction 4.2.7 Kinetic Friction 4.2.8 Dry Friction and Instabilities 4.2.9 Lubricated Friction 4.2.10 Stick–Slip 4.3 Frictional Behaviours 4.3.1 Basic Frictional Behaviours 4.3.2 Pre-sliding Regime 4.3.3 Gross Sliding Regime 4.3.4 The Stribeck Curve 4.3.5 Friction Lag 4.4 Lubrication and Roughness 4.4.1 Introduction 4.4.2 Lubricants 4.4.3 Lubrication Regimes 4.5 Causes of Friction 4.6 Basic Friction Theories and Laws 4.6.1 Basic Theories 4.6.2 Friction Laws 4.6.3 Adhesion and Ploughing Forces 4.7 Development of a Simple Shoe-Floor Tribology Model 4.7.1 Introduction 4.7.2 Development of a Theoretical Model 4.8 Conclusions 4.9 Summary References 5 Wear Behaviours and Mechanisms 5.1 Milieus 5.2 Confronting Issues of Wear Development 5.2.1 Introduction 5.2.2 Definitions and Development of Wear Studies 5.2.3 Scopes and Challenges 5.3 Wear Mechanisms and Basic Theories 5.3.1 Introduction 5.3.2 Wear Behaviours and Mechanisms 5.3.3 Types of Wear 5.3.4 Relationship Between Friction and Wear 5.4 Basic Theories of Wear Mechanisms 5.4.1 Adhesive Wear 5.4.2 Abrasive Wear 5.4.3 Surface Fatigue 5.4.4 Erosive Wear 5.4.5 Two-Body and Three-Body Abrasion Mechanisms 5.4.6 Relationships Amongst Wear, Scuffing, and Fatigue 5.5 Other Characteristics of Wear Behaviours 5.5.1 Advanced Considerations 5.5.2 Wear Volumes and Surface Textures 5.5.3 Wear Rates and Worn Surfaces 5.6 Friction and Wear Mechanisms at the Shoe-Floor Contact-Sliding Interface 5.6.1 Introduction 5.6.2 Theoretical Model Development for the Wear Mechanism 5.7 Wear Model for the Shoe-Floor Tribology System 5.8 Conclusions 5.9 Summary References Part III Shoe-Floor Tribology Systems 6 Developments of Friction and Wear Models for the Shoe-Floor-Environment 6.1 Milieus 6.2 Friction Mechanism at the Shoe-Floor Sliding Interface 6.2.1 Introduction 6.2.2 Adhesion Component 6.2.3 Deformation Component 6.3 Theoretical Model Development for the Friction Mechanism 6.3.1 Introduction 6.3.2 Theory Background 6.3.3 Formulation of a Frictional Model 6.3.4 Real Contact Area Versus Average Slopes 6.4 Theoretical Model Development for the Wear Mechanism 6.4.1 Theoretical Background 6.4.2 Main Hypotheses 6.4.3 Parametric Characterization of Wear Behaviours 6.4.4 Optical Measurement of a Shoe Contact Area 6.5 Conclusions 6.6 Summary References 7 Observation of the Floor Surface Changes in the Pedestrian Slip Resistance Measurements 7.1 Milieus 7.2 Introduction 7.3 Experimental Methods and Materials 7.3.1 Dynamic Friction Tester 7.3.2 Dynamic Slip Resistance Measurements 7.3.3 Measurements of Surface Roughness 7.3.4 Description of Surface Profiles 7.4 Results and Discussion 7.4.1 Overall Slip Resistance Results 7.4.2 Surface Analyses 7.5 Conclusions 7.6 Summary References 8 Engineering Assessment of Floors/Walkways: Practice for the Prevention of Pedestrian Fall Incidence 8.1 Milieus 8.2 Introduction 8.3 Development of Main Theory 8.4 Experimental Materials and Methods 8.4.1 Dynamic Friction Tester 8.4.2 Floor Specimens 8.4.3 Shoe Specimens 8.4.4 Environmental Conditions 8.4.5 Measurements of Surface Texture 8.4.6 Statistical Design and Analysis 8.5 Results 8.5.1 Slip Resistance Performances 8.5.2 Effect of the Floor Surface Finishes on Slip Resistance 8.5.3 Effect of the Shoes on Slip Resistance 8.6 Discussion 8.6.1 Overall Slip Resistance Performance 8.6.2 Interactions Between the Floor Types and Environments 8.6.3 Interactions Between the Shoe Types and Environments 8.6.4 Effect of the Surface Finishes on Slip Resistance 8.6.5 Peak Density Analysis 8.7 Conclusions 8.8 Precincts of the Current Chapter Study 8.9 Summary References 9 Development of a Tribology Model for Quantifying Slip Resistance Characteristics: Basic Concepts, Theories, Experiments, and Validations 9.1 Milieus 9.2 Introduction 9.3 Significance of This Chapter Study 9.4 Basic Theory Developments 9.4.1 Background 9.4.2 Comparative Surface Roughness (CSR) and Harmony (CSH) 9.4.3 Comparative Surface Harmony Index (CSHI) 9.5 Experimental Materials and Methods 9.5.1 Slip Resistance Measurements 9.5.2 Test Specimens 9.5.3 Slip Resistance Measurements 9.5.4 Measurements of Surface Texture 9.5.5 Dynamic Friction Test Conditions 9.5.6 Statistical Assessments 9.6 Results and Discussion 9.6.1 Overall Slip Resistance Performances 9.6.2 Surface Height Distributions and Profile Shapes 9.6.3 Surface Roughness Parameters 9.6.4 Wear Observations 9.6.5 Comparative Surface Mating (CSM) 9.7 Conclusions 9.8 Summary References Part IV Tribological Assessments of Shoes and Floors—Case Studies 10 Tribological Assessments of Shoe Surfaces: Identification of Wear Mechanisms and Applications for Slip Resistance Assessments—Case Study No. 1 10.1 Milieus 10.2 Introduction 10.3 Development of a Basic Theory 10.3.1 Background 10.3.2 Theoretical Development 10.3.3 Parametric Characterizations of the Shoe Wear 10.4 Experimental Materials and Methods 10.4.1 Friction Measuring Tester 10.4.2 Shoe Specimens 10.4.3 Floor Specimens 10.4.4 Slip Resistance Measurements 10.5 Results 10.5.1 Slip Resistance Performing 10.5.2 Surface Roughness Parameters and Correlations 10.5.3 SEM Observations 10.5.4 Morphological Characteristics 10.5.5 Initiation of Wear and Wear Patterns 10.6 Discussion 10.7 Conclusions 10.8 Summary References 11 Tribological Assessments of Shoe Surfaces: Identification of Wear Mechanisms and Applications for Slip Resistance Assessments—Case Study No. 2 11.1 Milieus 11.2 Introduction 11.3 Development of a Basic Theory 11.3.1 Main Hypothesis 11.3.2 Shoe Wear Model 11.4 Experimental Materials and Methods 11.4.1 Dynamic Friction Tester 11.4.2 Shoe Specimens 11.4.3 Floor Specimens 11.4.4 Test Conditions 11.4.5 Slip Resistance Measurements 11.4.6 Characterizations of Shoe Wear Behaviours 11.4.7 Statistical Analysis 11.5 Results and Discussion 11.5.1 Slip Resistance Performing 11.5.2 Quantitative Analysis 11.5.3 Qualitative Analysis 11.6 Conclusions 11.7 Precincts of the Current Chapter Study 11.8 Summary References 12 Tribological Assessments of Shoe Surfaces: Identification of Wear Mechanisms and Applications for Slip Resistance Assessments—Case Study No. 3 12.1 Milieus 12.2 Introduction 12.3 Development of Main Theory 12.4 Experimental Materials and Methods 12.4.1 Shoe Samples 12.4.2 Floor Samples 12.4.3 Dynamic Friction Measuring Tester 12.4.4 Slip Resistance Measurements 12.4.5 Surface Analysis: Two-Dimensional Characterisation 12.4.6 Wear Analysis: Three-Dimensional Characterisation 12.5 Results 12.5.1 Dynamic Friction Measurements 12.5.2 Surface Analysis 12.5.3 Wear Observation 12.5.4 Wear Debris and Particles 12.6 Discussion 12.6.1 Abrasion Patterns and Crack Formations 12.6.2 Crack Propagations 12.7 Conclusions 12.8 Summary References 13 Observation on Wear Developments of Floor/Walkway Surfaces: Applications to Pedestrian Fall Safety Assessments—Case Study No. 1 13.1 Milieus 13.2 Introduction 13.3 Experimental Materials and Methods 13.3.1 Floor Specimens 13.3.2 Shoe Specimens 13.3.3 Dynamic Friction Tester 13.3.4 Dynamic Friction Test Conditions 13.3.5 Test Arrangements 13.3.6 Quantitative Analyses 13.3.7 Qualitative Analyses 13.3.8 Statistical Assessments 13.4 Results 13.4.1 Dynamic Friction Tests 13.4.2 Surface Changes and Wear Assessments—Quantitative Analyses 13.4.3 Statistical Analyses 13.4.4 Surface Changes and Wear Assessments - Qualitative Analyses 13.5 Discussion 13.5.1 Evidence of Floor Wear Developments 13.5.2 Suggestion of a Flooring Wear Concept 13.6 Conclusions 13.7 Summary References 14 Observation on Wear Developments of Floor/Walkway Surfaces: Applications to Pedestrian Fall Safety Assessments—Case Study No. 2 14.1 Milieus 14.2 Introduction 14.3 Theory Model Development 14.3.1 Background 14.3.2 Flooring Wear Model 14.4 Experimental Materials and Methods 14.4.1 Floor Samples 14.4.2 Shoe Samples 14.4.3 Slip Tester 14.4.4 Test Conditions 14.4.5 Dynamic Friction Measurements 14.4.6 Surface Roughness Analysis 14.4.7 Microscopy Analysis 14.5 Results 14.5.1 Dynamic Friction Measurements 14.5.2 Flooring Wear Assessment: Numerical Analysis 14.5.3 Flooring Wear Assessment: Microscopy Analysis 14.5.4 Wear Products 14.6 Discussion 14.6.1 Flooring Wear Development: Numerical Observations 14.6.2 Flooring Wear Development: Surface Texture Analyses 14.6.3 Flooring Wear Development: Microscopy Observations 14.6.4 Validation of the Flooring Wear Model 14.7 Conclusions 14.8 Precincts of the Current Chapter Study 14.9 Summary References 15 Observation on Wear Developments of Floor/Walkway Surfaces: Applications to Pedestrian Fall Safety Assessments—Case Study No. 3 15.1 Milieus 15.2 Introduction 15.3 Experimental Materials and Methods 15.3.1 Floor Samples 15.3.2 Shoe Samples 15.3.3 Dynamic Friction Tester 15.3.4 Test Conditions 15.3.5 Measuring Surface Profiles 15.3.6 Observing Surface Structures 15.4 Results 15.4.1 Slip Resistance Performances 15.4.2 Wear Assessments—Measuring Surface Profiles 15.4.3 Wear Assessments—Observing Surface Structures 15.5 Discussion 15.5.1 Observation of Slip Resistance Performances 15.5.2 Recognition of Wear Developments 15.5.3 Verification of the Flooring Wear Model 15.6 Conclusions 15.7 Precincts of the Current Chapter Study 15.8 Summary References Part V Future Works and Recommendations 16 Future Works, Recommendations, and Conclusions 16.1 Milieus 16.2 Review of Overall Aims 16.3 Recommendations for Future Studies 16.3.1 Fundamental Issues 16.3.2 Effects of Surface Texture on Slip Resistance Properties 16.3.3 Practicality of Dry Slip Resistance Testing 16.3.4 Advanced Flooring Wear Theory and Model Developments 16.3.5 Advanced Shoe Wear Theory and Model Developments 16.4 Conclusions 16.5 Precincts of This Book References Author Index Subject Index