Designing with Plastics

Contents

1 Market Overview

1.1 Examples of Applications from Various Industry Sectors

1.1.1 Aerospace

1.1.2 Precision Engineering

1.1.3 Automotive Engineering

1.1.4 General Mechanical Engineering

1.1.5 Design of Technical Equipment

1.1.6 Construction Industry

1.2 Forecast

2 Structure and Properties

2.1 Chemical Structure (Constitution)

2.1.1 Degree of Polymerization – Relative Molecular Weight

2.1.2 Homopolymerization and Copolymerization

2.2 Intermolecular Binding Energies (Secondary Valence Bonds)

2.2.1 Absorption of Water by Polyamides

2.3 Spatial Arrangement of Atoms and Groups of Atoms in Molecules (Configuration)

2.3.1 Tacticity

2.3.2 Branching

2.3.3 Cross-Linking

2.4 Architecture of Polymer Systems

2.4.1 Homogeneous and Heterogeneous Polymer Mixtures

2.4.2 Plasticization

2.4.3 Fillers and Reinforcement

2.5 Morphology (Supermolecular Structures)

2.5.1 Amorphous Microstructure

2.5.2 Crystalline Microstructure

2.5.3 Anisotropy

2.6 Thermomechanical Ranges

2.6.1 Thermoplastics with Amorphous Structure

2.6.2 Thermoplastics with Semicrystalline Structure

2.6.3 Elastomers

2.6.4 Thermosets

3 Brief Description of the Properties of Generic Polymeric Materials

3.1 Thermoplastics

3.1.1 Polymer Blends

3.1.2 Functional Polymers

3.2 Elastomers

3.3 Thermosets

3.4 Fibrous Reinforcements

3.4.1 Glass Fibers

3.4.2 Carbon Fibers

3.4.3 Aramid Fibers

3.4.4 Metal Fibers, Whiskers, and Ceramic Fibers

4 Physical Properties – Characteristic Values – Test Methods and Procedures

4.1 Deformation Behavior under Uniaxial Dynamic Tensile Stress (Stress-Strain Experiments)

4.1.1 Molecular Deformation and Fracture Mechanisms

4.1.2 Characteristic Stress-Strain Curves

4.1.3 Determination of Stress-Strain Diagrams and Characteristic Properties of Materials

4.1.4 Effects of Temperature, Time, and Humidity on Stress-Strain Curves

4.1.5 Mathematical Description of Stress-Strain Curves

4.2 Deformation Behavior under Uniaxial, Long-Term, Static Tensile Loads (Tensile Creep Testing)

4.2.1 Mathematical Description of Creep Curves

4.3 Toughness and Impact Resistance

4.3.1 Determination of Tensile Stress-Strain Toughness

4.3.2 Determination of Toughness by Flexural Impact Test

4.3.3 Penetration or Dart Drop Impact Test

4.4 Behavior under Cyclic Loads

4.4.1 Determination of Characteristic Features of Fatigue

4.5 Poisson’s Ratio

4.6 Thermal Properties

4.6.1 Thermal Expansion

4.6.2 Dimensional Stability

4.6.3 Heat Aging

4.6.4 Summary Analysis of the Effects of Temperature

4.7 Tribological Properties

4.7.1 Fundamentals

4.7.2 Friction and Wear in Mated Polymer and Steel Surfaces

4.7.3 Friction and Wear in Mated Pairs of Polymeric Materials

4.7.5 Effect of Additives on Friction and Wear Properties

4.7.6 Stick-Slip

4.7.7 Jet Erosion

5 Calculations for Structures under Mechanical Load – Examples of Geometrically Simple Structural Parts under Static Loads

5.1 Specific Materials and Processing Problems

5.1.1 Deformation Behavior under Uniaxial Dynamic Tensile Stress

5.2 Determination of Strength

5.2.1 Basic Procedure for Structural Part Design

5.2.2 Uniaxial State of Stress

5.2.3 Multiaxial State of Stress

5.3 Calculation of Strains and Deformations

5.3.1 Linear Elastic Behavior

5.3.2 Nonlinear Elastic Behavior

5.4 Analysis of Stress and Deformation in Structures under Flexural Loads with the Aid of a Simple FE Approach

5.5 Calculation of Structural Parts Subjected to Impact Loads

5.6 Structural Design of Fiber-Composite Structures

5.6.1 Mechanical Properties of Laminates

5.6.2 Methods of Calculation

5.7 Computer-Aided Development

5.7.1 Computer-Aided Design (CAD)

5.7.2 Rapid Prototyping

5.7.3 Rapid Tooling

6 Design and Material Considerations for Parts Subjected to Mechanical Loads

6.1 Flexible Structures

6.1.1 Modulus of Elasticity

6.1.2 Design Geometry – Moment of Inertia

6.1.3 Load–Geometry Interactions

6.2 Flexurally Rigid Structures

6.3 Flexurally Flexible, Torsionally Rigid Structures

6.4 Flexurally Rigid, Torsionally Flexible Structures

6.5 Torsion-Resistant, Torsionally Rigid Structures

6.6 Flexurally and Torsionally Rigid Structures

6.7 Torsionally Flexible Structures

6.8 Tension-Proof, Tensionally Rigid and Torsionally Flexible Structures

6.9 High Shear-Strength, Shear-Resistant Structures

6.10 Pressure-Yielding and Compression-Resistant Structures

6.11 Multifunctional Structures

6.12 Thermal Expansion and Thermal Stress

6.13 Universal Joints

7 Designing for Production

7.1 Mold Filling

7.1.1 Simulation of the Filling Operation

7.1.2 Causes of Orientation in Moldings

7.1.3 Causes for Formation of Weld Lines and Air Pockets

7.2 Cooling and Solidification

7.2.1 Cooling Rate

7.2.2 Changes in Dimensions and Tolerances

7.2.3 Warpage

7.3 Demolding

7.3.1 Draft

7.3.2 Demolding of Undercuts

7.3.3 Avoidance of Undercuts

7.4 Sandwich Molding (Co-Injection Molding)

7.4.1 Two-Color Injection Molding

7.4.2 Rigid-Flexible Combinations

7.4.3 Gas Injection Technology (GIT)

7.4.5 External Gas Pressure Technology

8 Flexing Elements

8.1 Snap-Fit Joints

8.1.1 Snap-Fit Beams

8.1.2 Torsional Snap-Fit Joints

8.1.3 Annular Snap-Fit Joints

8.1.4 Segmented Annular Snap-Fit Joints

8.2 Elastic Elements

8.2.1 Elastic Thermoplastic Materials

8.2.2 Springs Made of Fiber-Plastic Composites (Glass-Fiber and Carbon-Fiber Reinforced Plastic)

8.3 Integral Hinges and Integral Joints

8.3.1 Manufacture of Integral Hinges and Integral Joints

8.3.2 Design

8.3.3 Materials

8.3.4 Integral Hinge Design Calculations

8.3.5 Applications with Integral Hinges

9 Mechanical Fasteners

9.1 Molded Threads and Threads Produced by Machining

9.1.1 Screws and Bolts Made of Polymeric Material

9.1.2 Injection-Molded, Blow-Molded, and Machined Threads

9.2 Threaded Inserts

9.2.1 Encapsulated Threaded Inserts

9.2.2 Threaded Inserts Embedded by Ultrasound

9.2.3 Press-In Threaded Inserts

9.2.4 Expansion Inserts

9.2.5 Screw-In Inserts

9.2.6 Inserts Made of Polymeric Materials

9.2.7 Comparative Evaluation of the Various Inserts

9.2.8 Behavior under Dynamic Loads

9.3 Self-Threading Screws

9.3.1 Screw Shapes and Geometries

9.3.2 Design of the Screw Boss

9.3.3 Calculation of Key Variables in a Self-Threading Screw Joint

10 Ribbed Structures

10.1 Comparison with Other Methods of Reinforcement

10.1.1 Increasing the Modulus of Elasticity

10.1.2 Increasing Wall Thickness

10.1.3 Crimps and Corrugations

10.2 General Considerations in Ribbed Structures

10.2.1 Rib Height

10.2.2 Rib Position

10.2.3 Number of Ribs (Consumption of Material)

10.2.4 Support

10.3 Design Rules for Injection-Molded Ribs

10.3.1 Rib Thickness

10.3.2 Cooling Time

10.3.3 Injection Direction

10.3.4 Rib Intersection Points (Nodes)

10.4 Design Rules for Ribs Produced by Gas-Assist Molding Methods

10.5 Design Rules for Blow-Molded Ribs and Corrugations

10.5.1 Blow-Molded Corrugations

10.5.2 Blow-Molded Ribs

10.6 Design Rules for Compression-Molded Ribs

10.6.1 Manual Processing (Hand Lay-Up Process)

10.6.2 Compression Molding

11 Gear Wheels

11.1 Calculation of the Tooth and Tooth Face Temperatures in Spur Gears

11.1.1 Blok’s Flash Temperature Hypothesis

11.1.2 Takanashi Method for Calculating Temperature

11.1.3 Hachmann and Strickle Method for Calculating Temperature

11.1.4 Comparison of Methods of Calculating Temperature

11.1.5 Optimized Temperature Calculation

11.2 Calculation of Load-Bearing Capacity

11.2.1 Tooth Damage

11.2.2 General Parameters

11.2.3 Calculation of the Load-Bearing Capacity of the Tooth Base

11.2.4 Calculation of the Load-Bearing Capacity of the Tooth Flank

11.2.5 Calculation of Tooth Deformation

11.3 Design

11.3.1 Injection Molding

11.3.2 Production of Gears by Machining

11.3.3 Shaft-Hub Joints

12 Friction Bearings

12.1 Friction Bearing Damage

12.2 Calculation of Load-Bearing Capacity for Bearings

12.2.1 Calculation of Mean Bearing Temperature

12.2.2 Calculation of Temperature of Sliding Surface

12.2.3 Static Load-Bearing Capacity

12.2.4 Dynamic Load-Bearing Capacity

12.3 Bearing Design

12.3.1 Bearing Clearance

12.3.2 Bearing Wall Thickness

12.3.3 Bearing Production

12.3.4 Design Examples of Bearings

13 Wheels and Rollers

13.1 Roller Damage

13.2 Calculation of Load-Bearing Capacity

13.2.1 Pressure Parameter as an Approximate Design Limit

13.2.2 Deformation of Rollers under Static Load

13.2.3 Rollers under Dynamic Load

Index