1 Introduction
2 Experimental procedure
2.1 Materials
Chemical composition EN AW-6014, T4 (weight %) | |||||||||
---|---|---|---|---|---|---|---|---|---|
Si | Fe | Cu | Mn | Mg | Cr | Zn | Ti | V | |
Min | 0.30 | 0.05 | 0.40 | ||||||
Max | 0.60 | 0.35 | 0.25 | 0.20 | 0.80 | 0.20 | 0.10 | 0.10 | 0.10 |
Mechanical properties EN AW-6014, T4 | ||||
---|---|---|---|---|
Density (kg/m3) | Young modulus (N/mm2) | Yield stress (MPa) | UTS (MPa) | Ag (%) |
2.7 × 108 | 70,000 | 130 | 190 | 23 |
Chemical composition 38B2 (weight %) | |||||||||
---|---|---|---|---|---|---|---|---|---|
Si | C | Cu | Mn | P | S | Cr | Mo | B | |
Min | 0.35 | 0.60 | 0.0005 | ||||||
Max | 0.3 | 0.40 | 0.25 | 0.90 | 0.025 | 0.025 | 0.3 | – | 0.0008 |
Mechanical properties 38B2 | ||||
---|---|---|---|---|
Density (kg/m3) | Young modulus (N/mm2) | Hardness (HV) | ||
7.87 × 108 | 210,000 | 480 |
Chemical composition C35 (weight %) | |||||||||
---|---|---|---|---|---|---|---|---|---|
C | Si | Mn | P | S | Cr | Mo | Ni | Cu | |
Min | 0.32 | 0.50 | |||||||
Max | 0.39 | 0.30 | 0.80 | 0.025 | 0.025 | 0.25 |
Mechanical properties C35 | ||||
---|---|---|---|---|
Density (kg/m3) | Young modulus (N/mm2) | Hardness (HV) | ||
7.87 × 108 | 210,000 | 480 |
2.2 Multi-range capable rivets
2.3 Joining systems
2.4 Evaluation of the joint
2.5 Determination of the load-bearing capacity
3 Results and discussion
Punch-sided sheet | Thickness (mm) | Die-sided sheet | Thickness (mm) | |
---|---|---|---|---|
Combination A | EN AW-6014 | 1.0 | EN AW-6014 | 2.0 |
Combination B | EN AW-6014 | 1.5 | EN AW-6014 | 2.0 |
Combination C | EN AW-6014 | 2.0 | EN AW-6014 | 2.0 |
3.1 Joint formation
3.1.1 Without rivet head deformation
3.1.2 With rivet head deformation
3.2 Shear-load
3.2.1 Without rivet head deformation
3.2.2 With rivet head deformation
3.3 Cross tensile load
3.3.1 Without rivet head deformation
3.3.2 With head deformation
3.4 Comparison of the load-bearing capacities
SPR | V-SPR (without head deformation) | V-SPR (with head deformation) | |||||||
---|---|---|---|---|---|---|---|---|---|
f | tr | ph | f | tr | ph | f | tr | ph | |
Combination A | 0.52 | 0.15 | 0.04 | 0.45 | 0.37 | 0.02 | 0.38 | 0.32 | 0.35 |
Combination B | 0.45 | 0.25 | 0.05 | 0.38 | 0.60 | − 0.26 | 0.28 | 0.53 | 0.02 |
Combination C | 0.35 | 0.18 | 0.11 | 0.35 | 0.79 | − 0.58 | 0.15 | 0.82 | − 0.17 |
3.4.1 Shear load
3.4.2 Cross tensile load
4 Summary and outlook
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In the conducted research, the process sequence of a versatile semi-tubular self-piercing riveting process is presented. The versatility is achieved by multi-range capable semi-tubular self-piercing rivets, in which the rivet head is either deformed or non-deformed. Therefore, a joining system with extended punch-sided tool actuator technology, which consists of independent and freely parameterisable punches is set up.
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The process presented enables the versatility of semi-tubular self-piercing riveting to be increased while at the same time achieving high joint load-bearing capacities. At the same time, a reduction of the rivet and die geometries is achieved, which increases the process efficiency.
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Both rivet geometries (with and without head deformation) offer the possibility of a large multi-range capability. Sheet thickness changes of up to 1.0 mm can be covered. At the same time, only one die geometry is needed to create the joints. For the same joints with conventional rivets, three rivet length and three die geometries are required.
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High load bearing capacity under shear tensile and cross tensile load is demonstrated by both rivet geometries. The forces, displacements and energy absorption achieved is significantly greater for the rivet geometry with head deformation than for the rivet geometry without head deformation.
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The load-bearing capacity of the multi-range capable rivet without head deformation is significantly influenced by the number and degree of filling of the annular ring grooves in the head area. If more ring grooves are filled, the cross-section of the loaded surface increases, which reduces occurring stresses and allows greater load-bearing capacities to be achieved. In addition, the load-bearing capacity is influenced by the stiffness of the punch-sided joining part.
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The load-bearing capacity of the riveted joints with head deformation is comparable to the behaviour of conventionally SPR joints. In part, greater forces can be reached and higher energy can be absorbed. The load-bearing capacity of the joint depends in particular on the formation of the interlock in the die-sided joining part. Due to lower penetration depths, the expansion of the rivet is reduced in case of large sheet thicknesses used, resulting in a smaller interlock formation. For this reason, a lower load-bearing capacity could be identified here. A negative influence on the load-bearing capacity due to the deformation of the rivet head could not be determined.