Talat Lecture 4703: Design And Calculation Of Adhesive Joints
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TALAT Lecture 4703
Adhesive Joints Design and Calculation 9 pages, 10 figures Basic Level prepared by Lutz Dorn, Technische Universität, Berlin
Objectives: − to describe the basic types of loadings of adhesive joints and to give examples of recommended joint designs − to calculate the strength of adhesive joints
Prerequisites: − general background in production engineering and material science − background in mechanics and polymer science
Date of Issue: 1994 EAA - European Aluminium Association
4703 Design and Calculation of Adhesive Joints Table of Contents 4703 Design and Calculation of Adhesive Joints ............................................2 4703.01 Design Recommendations for Adhesive Joints....................................... 2 Basic Types of Loadings of Adhesive Joint Geometries .........................................2 Examples for Joint Designs .....................................................................................4 4703.02 Calculation of Adhesive Joint Strength .................................................. 6 4703.03 Application Examples............................................................................... 7 4703.04 Literature/ References .............................................................................. 8 4703.05 List of Figures.............................................................................................. 9
4703.01 Design Recommendations for Adhesive Joints • •
Basic types of loadings of adhesive joint geometries Examples for joint designs: − Design of corner joints − Design of hollow section joints − Design of tube joints
Basic Types of Loadings of Adhesive Joint Geometries
Just as in the case of welding, the adhesive joint has to be specially optimised for adhesive joining in order to have a joint of optimal strength. Of the possible loading types which an adhesive joint can be subjected to, it is most suited for shear, torsion and compressive loads. Tensile and in particular cleavage or peeling forces should be avoided (Figure 4703.01.01).
TALAT 4703
2
Design of Adhesive Metal Joints F
F F F
Tension Tensile - Shear
F
F
Cleavage
Peeling M M
F
t
t
Torsion
alu
Types of Stressing for Adhesive Joint Geometries
4703.01.01
Training in Aluminium Application Technologies
Design types which avoid peeling stresses in adesive ints of metals are illustrated in Figure 4703.01.02.
Design of Adhesive Metal Joints Peeling Stress
Mechanical Reinforcement of a Joint Part End by :
Additional Riveting / Screwing
Folding
Increasing Rigidity
Increasing Area
alu
Possibilities of Reducing Peeling Stress
4703.01.02
Training in Aluminium Application Technologies
Besides the most widely used (one-sided) lap joints shown in Figure 4701.01.01, Figure 4703.01.03 illustrates further possible designs for constructing overlapping adhesive joints. Scarf joints are most suitable for tensile-shear loading since the load distribution is favourable. These joints can, however, be used only for large joint part thicknesses and are complicated to manufacture TALAT 4703
3
Design of Adhesive Metal Joints Double Lap
Joggle Lap
b
A=2 xb
A=xb
b x
x
Single-Sided Strapped Bevelled Single-Sided Lap A=xb/2
b
A=xb
b
x x
Double-Sided Strapped Scarf A=xb
b
b x
x
A=xb/cos(α)
α
Designing Overlapped Adhesive Joints alu
Designing Adhesive Lap Joints
4703.01.03
Training in Aluminium Application Technologies
Examples for Joint Designs Designs which have proved most successful for corner joints, closed-sectioned profile joints and tube joints are illustrated in Figure 4703.01.04, Figure 4703.01.05, and Figure 4703.01.06. While joining tubes of different coefficients of thermal expansion adhesively, the tube with the larger expansion should be designed to be on the outside.
Design of Adhesive Metal Joints
Corner Joints (Examples) alu
Examples for Joint Designs: Corner Joints
Training in Aluminium Application Technologies
TALAT 4703
4
4703.01.04
Design of Adhesive Metal Joints
Closed Profiles (Examples) Examples for Joint Designs: Closed Profiles
alu
4703.01.05
Training in Aluminium Application Technologies
Design of Adhesive Metal Joints
Tube Joints (Examples) alu
Examples for Joint Designs: Tube Joints
Training in Aluminium Application Technologies
TALAT 4703
5
4703.01.06
4703.02 Calculation of Adhesive Joint Strength Figure 4703.02.01 shows a rough method of calculating the strength of a single-sided lap joint based on a simplified form of the Volker equation according to Schliekelmann.
Calculation of Adhesive Joints The Mean Tensile-Shear Stress at Failure of Adhesive τB m is:
τB m = K ⋅ M ⋅ f
where the Adhesive Factor is:
K = τ B max ⋅
2d G
τB max = max. Tensile-Shear Stress at Failure of Adhesive Joint d = Adhesive Layer Thickness G = Shear Modulus and the Metal Factor is:
M= E E = Modulus of Elasticity of Joint Material
and the Design Factor is:
f=
s lü
s = Joint Thickness lü = Overlap Length This results in the Following Final Equation for the Mean Tensile-Shear Stress:
τ B m = τ B max ⋅
alu
Calculation of Adhesive Joints
2Esd 2 Glü
4703.02.01
Training in Aluminium Application Technologies
Depending on the application, it is necessary to choose the appropriate safety factor as well as a number of design and load-dependent reducing factors.
TALAT 4703
6
4703.03 Application Examples Typical application examples for adhesively joint metal constructions are layered or laminated, shell and sandwich constructions Figure 4703.03.01, Figure 4703.03.02, and Figure 4703.03.03. Sandwich constructions are only possible with adhesive joining.
Practical Examples
Laminated Constructions alu
Example of Joints: Laminated Construction
4703.03.01
Training in Aluminium Application Technologies
Practical Examples
Shell Constructions
alu
Example of Joints: Shell Construction
Training in Aluminium Application Technologies
TALAT 4703
7
4703.03.02
Practical Examples
Corrugated Sheet
Balsa Cross-Cut Wood
Supported Core Sandwich Constructions
alu Training in Aluminium Application Technologies
Examples of Joints: Supported Core Sandwich Constructions
4703.03.03
Other applications where adhesive joints are being successfully used are, for example, shaft-hub joints, screw-locking, sealing, in combination with other joining methods i.e., spot welding, riveting or folding.
4703.04 Literature/ References 1. Schliekelmann, R.J.: Klebtechnische Erfahrungen aus dem Flug- und Raumfahrzeugbau. Zeitschriften für Schweißtechnik (Schweiz) 16 (1966), H. 8, S. 319-327. 2. Schliekelmann, R.J.: Metallkleben - Konstruktion und Fertigung in der Praxis. DVS Verlag Düsseldorf, 1972. 3. Adam, R. and Wake, W.: Structural adhesive joints in engineering. Elsevier Applied Science Publishers London and New York 1984. 4. Hart-Smith, L.J.: Designing adhesive bonds. Akhesives Age 21 (1978) 10, S. 3237. 5. Hart-Smith, L.J.: Further developments in the design and analysis of adhesivebonded structural joints. ASTM STP 749, ed by K.T. Kedward, American Society for Testing and Materials 1980, pp-3-31.
TALAT 4703
8
6. Dorn, L. und Salem, N.: Klebgerechtes Gestalten von Kunststoff-MetallKlebverbindungen. Maschinenmarkt Würzburg 99 (1993) Nr. 35, S. 66-72. 7. Schlimmer, M.: Formulierung des Klebstoffverhaltens im Zugscherversuch mit Berücksichtigung der Schädigung. Schweißen und Schneiden 38 (1986) H. 11, S. 545-550. 8. Kinloch, A.J. and Smart, N.R.: Bonding and failure mechanisms in aluminium alloy adhesive joints. Journal of Adhesion 12 (1981), pp. 23-35.
4703.05 List of Figures
Figure No. 4703.01.01 4703.01.02 4703.01.03 4703.01.04 4703.01.05 4703.01.06
Figure Title (Overhead) Types of Stressing for Adhesive Joint Geometries Possibilities of Reducing Peeling Stress Designing Adhesive Lap Joints Examples for Joint Designs: Corner Joints Examples for Joint Designs: Closed Profiles Examples for Joint Designs: Tube Joints
4703.02.01
Calculation of Adhesive Joints
4703.03.01 4703.03.02 4703.03.03
Example of Joints: Laminated Construction Example of Joints: Shell Construction Example of Joints: Supported Core Sandwich Constructions
TALAT 4703
9
Adhesive Joints Design and Calculation 9 pages, 10 figures Basic Level prepared by Lutz Dorn, Technische Universität, Berlin
Objectives: − to describe the basic types of loadings of adhesive joints and to give examples of recommended joint designs − to calculate the strength of adhesive joints
Prerequisites: − general background in production engineering and material science − background in mechanics and polymer science
Date of Issue: 1994 EAA - European Aluminium Association
4703 Design and Calculation of Adhesive Joints Table of Contents 4703 Design and Calculation of Adhesive Joints ............................................2 4703.01 Design Recommendations for Adhesive Joints....................................... 2 Basic Types of Loadings of Adhesive Joint Geometries .........................................2 Examples for Joint Designs .....................................................................................4 4703.02 Calculation of Adhesive Joint Strength .................................................. 6 4703.03 Application Examples............................................................................... 7 4703.04 Literature/ References .............................................................................. 8 4703.05 List of Figures.............................................................................................. 9
4703.01 Design Recommendations for Adhesive Joints • •
Basic types of loadings of adhesive joint geometries Examples for joint designs: − Design of corner joints − Design of hollow section joints − Design of tube joints
Basic Types of Loadings of Adhesive Joint Geometries
Just as in the case of welding, the adhesive joint has to be specially optimised for adhesive joining in order to have a joint of optimal strength. Of the possible loading types which an adhesive joint can be subjected to, it is most suited for shear, torsion and compressive loads. Tensile and in particular cleavage or peeling forces should be avoided (Figure 4703.01.01).
TALAT 4703
2
Design of Adhesive Metal Joints F
F F F
Tension Tensile - Shear
F
F
Cleavage
Peeling M M
F
t
t
Torsion
alu
Types of Stressing for Adhesive Joint Geometries
4703.01.01
Training in Aluminium Application Technologies
Design types which avoid peeling stresses in adesive ints of metals are illustrated in Figure 4703.01.02.
Design of Adhesive Metal Joints Peeling Stress
Mechanical Reinforcement of a Joint Part End by :
Additional Riveting / Screwing
Folding
Increasing Rigidity
Increasing Area
alu
Possibilities of Reducing Peeling Stress
4703.01.02
Training in Aluminium Application Technologies
Besides the most widely used (one-sided) lap joints shown in Figure 4701.01.01, Figure 4703.01.03 illustrates further possible designs for constructing overlapping adhesive joints. Scarf joints are most suitable for tensile-shear loading since the load distribution is favourable. These joints can, however, be used only for large joint part thicknesses and are complicated to manufacture TALAT 4703
3
Design of Adhesive Metal Joints Double Lap
Joggle Lap
b
A=2 xb
A=xb
b x
x
Single-Sided Strapped Bevelled Single-Sided Lap A=xb/2
b
A=xb
b
x x
Double-Sided Strapped Scarf A=xb
b
b x
x
A=xb/cos(α)
α
Designing Overlapped Adhesive Joints alu
Designing Adhesive Lap Joints
4703.01.03
Training in Aluminium Application Technologies
Examples for Joint Designs Designs which have proved most successful for corner joints, closed-sectioned profile joints and tube joints are illustrated in Figure 4703.01.04, Figure 4703.01.05, and Figure 4703.01.06. While joining tubes of different coefficients of thermal expansion adhesively, the tube with the larger expansion should be designed to be on the outside.
Design of Adhesive Metal Joints
Corner Joints (Examples) alu
Examples for Joint Designs: Corner Joints
Training in Aluminium Application Technologies
TALAT 4703
4
4703.01.04
Design of Adhesive Metal Joints
Closed Profiles (Examples) Examples for Joint Designs: Closed Profiles
alu
4703.01.05
Training in Aluminium Application Technologies
Design of Adhesive Metal Joints
Tube Joints (Examples) alu
Examples for Joint Designs: Tube Joints
Training in Aluminium Application Technologies
TALAT 4703
5
4703.01.06
4703.02 Calculation of Adhesive Joint Strength Figure 4703.02.01 shows a rough method of calculating the strength of a single-sided lap joint based on a simplified form of the Volker equation according to Schliekelmann.
Calculation of Adhesive Joints The Mean Tensile-Shear Stress at Failure of Adhesive τB m is:
τB m = K ⋅ M ⋅ f
where the Adhesive Factor is:
K = τ B max ⋅
2d G
τB max = max. Tensile-Shear Stress at Failure of Adhesive Joint d = Adhesive Layer Thickness G = Shear Modulus and the Metal Factor is:
M= E E = Modulus of Elasticity of Joint Material
and the Design Factor is:
f=
s lü
s = Joint Thickness lü = Overlap Length This results in the Following Final Equation for the Mean Tensile-Shear Stress:
τ B m = τ B max ⋅
alu
Calculation of Adhesive Joints
2Esd 2 Glü
4703.02.01
Training in Aluminium Application Technologies
Depending on the application, it is necessary to choose the appropriate safety factor as well as a number of design and load-dependent reducing factors.
TALAT 4703
6
4703.03 Application Examples Typical application examples for adhesively joint metal constructions are layered or laminated, shell and sandwich constructions Figure 4703.03.01, Figure 4703.03.02, and Figure 4703.03.03. Sandwich constructions are only possible with adhesive joining.
Practical Examples
Laminated Constructions alu
Example of Joints: Laminated Construction
4703.03.01
Training in Aluminium Application Technologies
Practical Examples
Shell Constructions
alu
Example of Joints: Shell Construction
Training in Aluminium Application Technologies
TALAT 4703
7
4703.03.02
Practical Examples
Corrugated Sheet
Balsa Cross-Cut Wood
Supported Core Sandwich Constructions
alu Training in Aluminium Application Technologies
Examples of Joints: Supported Core Sandwich Constructions
4703.03.03
Other applications where adhesive joints are being successfully used are, for example, shaft-hub joints, screw-locking, sealing, in combination with other joining methods i.e., spot welding, riveting or folding.
4703.04 Literature/ References 1. Schliekelmann, R.J.: Klebtechnische Erfahrungen aus dem Flug- und Raumfahrzeugbau. Zeitschriften für Schweißtechnik (Schweiz) 16 (1966), H. 8, S. 319-327. 2. Schliekelmann, R.J.: Metallkleben - Konstruktion und Fertigung in der Praxis. DVS Verlag Düsseldorf, 1972. 3. Adam, R. and Wake, W.: Structural adhesive joints in engineering. Elsevier Applied Science Publishers London and New York 1984. 4. Hart-Smith, L.J.: Designing adhesive bonds. Akhesives Age 21 (1978) 10, S. 3237. 5. Hart-Smith, L.J.: Further developments in the design and analysis of adhesivebonded structural joints. ASTM STP 749, ed by K.T. Kedward, American Society for Testing and Materials 1980, pp-3-31.
TALAT 4703
8
6. Dorn, L. und Salem, N.: Klebgerechtes Gestalten von Kunststoff-MetallKlebverbindungen. Maschinenmarkt Würzburg 99 (1993) Nr. 35, S. 66-72. 7. Schlimmer, M.: Formulierung des Klebstoffverhaltens im Zugscherversuch mit Berücksichtigung der Schädigung. Schweißen und Schneiden 38 (1986) H. 11, S. 545-550. 8. Kinloch, A.J. and Smart, N.R.: Bonding and failure mechanisms in aluminium alloy adhesive joints. Journal of Adhesion 12 (1981), pp. 23-35.
4703.05 List of Figures
Figure No. 4703.01.01 4703.01.02 4703.01.03 4703.01.04 4703.01.05 4703.01.06
Figure Title (Overhead) Types of Stressing for Adhesive Joint Geometries Possibilities of Reducing Peeling Stress Designing Adhesive Lap Joints Examples for Joint Designs: Corner Joints Examples for Joint Designs: Closed Profiles Examples for Joint Designs: Tube Joints
4703.02.01
Calculation of Adhesive Joints
4703.03.01 4703.03.02 4703.03.03
Example of Joints: Laminated Construction Example of Joints: Shell Construction Example of Joints: Supported Core Sandwich Constructions
TALAT 4703
9
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