Mathias Bobbert
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View article: Application of stress-state-dependent ductile damage and failure model to clinch joining for a wide range of tool and material combinations
Application of stress-state-dependent ductile damage and failure model to clinch joining for a wide range of tool and material combinations Open
The clinch joining process is simulated for 22 different tool- and material-combinations, using a modular axisymmetric finite element simulation model. Two ductile metals are considered for the sheets, namely the dual-phase steel HCT590X a…
View article: Mechanical joinability of microstructurally graded structural components manufactured from hypoeutectic aluminium casting alloys
Mechanical joinability of microstructurally graded structural components manufactured from hypoeutectic aluminium casting alloys Open
Lightweight design is a driving concept in modern automotive engineering to minimize resource consumption over a vehicle's lifecycle through multi-material design, which relies on the use of joining techniques in car body fabrication. Mult…
View article: Development of a friction model for the numerical simulation of clinching processes
Development of a friction model for the numerical simulation of clinching processes Open
In numerical simulations of mechanical joining processes, such as clinching, modeling of material behavior is of decisive importance. In addition to the correct representation of plasticity and damage mechanisms, this primarily includes mo…
View article: Material Parameter Identification for a Stress-State-Dependent Ductile Damage and Failure Model Applied to Clinch Joining
Material Parameter Identification for a Stress-State-Dependent Ductile Damage and Failure Model Applied to Clinch Joining Open
Similar to bulk metal forming, clinch joining is characterised by large plastic deformations and a variety of different 3D stress states, including severe compression. However, inherent to plastic forming is the nucleation and growth of de…
View article: Influence of local heat treatment of rivets on the joint formation of a versatile joining process
Influence of local heat treatment of rivets on the joint formation of a versatile joining process Open
An efficient lightweight construction method is the combination of different materials in order to adapt the structure to the applied load. To join these multi-material structures mechanical joining technologies are applied. However, the r…
View article: Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting
Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting Open
AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks dur…
View article: Joining of multi-material structures using a versatile self-piercing riveting process
Joining of multi-material structures using a versatile self-piercing riveting process Open
Due to the increasing use of multi-material constructions and the resulting material incompatibilities, mechanical joining technologies are gaining in importance. The reasons for this are the variety of joining possibilities as well as hig…
View article: Experimental and Numerical Investigation on Manufacturing-Induced Pre-Strain on the Load-Bearing Capacity of Clinched Joints
Experimental and Numerical Investigation on Manufacturing-Induced Pre-Strain on the Load-Bearing Capacity of Clinched Joints Open
Background. Clinching is a conventional cold forming process in which two or more sheets can be joined without auxiliary parts. A pre-forming of the parts to be joined, which is introduced by previous manufacturing steps, has an influence …
View article: Functionality Study of an Optical Measurement Concept for Local Force Signal Determination in High Strain Rate Tensile Tests
Functionality Study of an Optical Measurement Concept for Local Force Signal Determination in High Strain Rate Tensile Tests Open
Many mechanical material properties show a dependence on the strain rate, e.g. yield stress or elongation at fracture. The quantitative description of the material behavior under dynamic loading is of major importance for the evaluation of…
View article: Mechanical joining in versatile process chains
Mechanical joining in versatile process chains Open
The use of mechanical joining technologies offers the possibility of joining mixed material structures, which are used in particular in lightweight construction. An integrated securing of the joinability in versatile process chains is curr…
View article: Numerical and experimental identification of fatigue crack initiation sites in clinched joints
Numerical and experimental identification of fatigue crack initiation sites in clinched joints Open
In this paper, a study based on experimental and numerical simulations is performed to analyze fatigue cracks in clinched joints. An experimental investigation is conducted to determine the failure modes of clinched joints under cyclic loa…
View article: Provision of cross-domain knowledge in mechanical joining using ontologies
Provision of cross-domain knowledge in mechanical joining using ontologies Open
Since the application of mechanical joining methods, such as clinching or riveting, offers a robust solution for the generation of advanced multi-material connections, the use in the field of lightweight designs (e.g. automotive industry) …
View article: Numerical investigation of the clinched joint loadings considering the initial pre-strain in the joining area
Numerical investigation of the clinched joint loadings considering the initial pre-strain in the joining area Open
The components of a body in white consist of many individual thin-walled sheet metal parts, which usually are manufactured in deep-drawing processes. In general, the conditions in a deep-drawing process change due to changing tribology con…
View article: Determining the properties of multi-range semi-tubular self-piercing riveted joints
Determining the properties of multi-range semi-tubular self-piercing riveted joints Open
By applying a variety of strategies, including both the development of new drive concepts as well as the use of lightweight constructions, it is intended to meet the climate targets set by the Paris Agreement. Multi-material design is ofte…
View article: Concept development of a method for identifying friction coefficients for the numerical simulation of clinching processes
Concept development of a method for identifying friction coefficients for the numerical simulation of clinching processes Open
In order to reduce fuel consumption and thus pollutant emissions, the automotive industry is increasingly developing lightweight construction concepts that are accompanied by an increasing usage of aluminum materials. Due to poor weldabili…
View article: NFDI-MatWerk: Participant Projects & Infrastructure Use Cases
NFDI-MatWerk: Participant Projects & Infrastructure Use Cases Open
This document includes the complete list and descriptions of the Participant Projects (PPs) and related Infrastructure-Use-Cases (IUCs) the consortium NFDI-MatWerk referred to within its proposal. For the NFDI-MatWerk proposal, refer to ht…
View article: Joining suitability of cast aluminium for self-piercing riveting
Joining suitability of cast aluminium for self-piercing riveting Open
Due to the increasing importance of reducing CO 2 emissions, lightweight construction strategies are highly emphasized in the automotive industry. One of these strategies is lightweight moulding, which is used, for example, in the space fr…
View article: Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters
Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters Open
Driven by the CO2-emission law by the European government and the increasing costs for raw materials as well as energy, the automotive industry is increasingly using multi-material constructions. This leads to a continuous increase in the …
View article: Further development of a numerical method for analyzing the load capacity of clinched joints in versatile process chains
Further development of a numerical method for analyzing the load capacity of clinched joints in versatile process chains Open
In many branches of production, components using large number of joints are combined together to make complex structures. The use of mechanical joining techniques offers the possibility to join structures with a wide range of material/geom…
View article: Novel Process Approach for in-situ Insertion of Functional Elements in RTM-Applications
Novel Process Approach for in-situ Insertion of Functional Elements in RTM-Applications Open
Lightweight design in vehicles leads to an increasing use of fibre-reinforced-plastics (FRP). To ensure the possibility of detachable joints in those constructions specific joining technologies have to be developed. Available technologies …
View article: Tolerance Analysis of Adhesive Bonds in Crash Simulation
Tolerance Analysis of Adhesive Bonds in Crash Simulation Open
The influences of geometrical parameters like adhesive layer thickness and gap-filling on the mechanical properties of adhesively bonded joints are investigated by means of experimental studies with controlled parameter variations. In addi…