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Professorship Machine Elements and Product Development
Professorship MP

News

Particle-induced wear of plain bearings

01.07.2024

Thin film polymers are increasingly being used in plain bearing systems due to their excellent sliding and emergency running properties. Due to the relatively low modulus of elasticity, these systems are designed with very thin layers. Otherwise, the negative properties of compliance, creep and poor heat transfer would predominate. However, the low layer thicknesses make the bearing systems highly susceptible to particle penetration and wear. One focus of the research institute’s investigations is therefore on extreme adhesion, such as that caused by particle-induced wear.

Bearing creep

17.06.2024

Roller bearings are an essential component in machine systems. Point or line loads act in the bearing rings, which are superimposed with a rotation. The resulting elastic deformations of the bearing rings lead to a relative movement between the outer bearing ring and housing or inner bearing ring and shaft. This relative movement accumulates over time and can lead to wear in the contact surfaces. This phenomenon has been the subject of IKAT’s dynamic simulation research ever since. Numerous research projects deal with design methods and analyses to prevent ring creep.

Summer School Design Society

14.06.2024

Ms. Nettlenbusch attends the Design Society’s Summer School in Malta, which is celebrating its 25th anniversary. The school teaches methods for writing a dissertation. The focus is on the development of research questions and the extraction of research hypotheses. At the same time, methods for self-organisation and structuring the dissertation were taught. An interdisciplinary exchange of researchers from different countries took place. We are looking forward to the next event of the Design Society.

Multiaxial fatigue in contacts

03.06.2024

The research issues associated with the fatigue strength of multi-axially loaded shaft-hub-connections (WNV) combine two important core topics that are continuously addressed at IKAT. On the one hand, complicated stress states, so-called non-proportional stresses, occur at the point of failure, which can only be evaluated using special strength hypotheses. In addition, tribological influencing variables, such as relative movement in contact (slip) and frictional shear stresses, lead to modified failure mechanisms, which are more critical to evaluate compared to classic/known notches on the free surfaces. Using the multiaxial test rig shown here, we are able to realize any application-specific superposition of rotating bending and cyclic torsion. Subsequent simulations and numerical interpretations of the experimental results of the stress-mechanical and tribological loading finally lead to calculation methods, which are suitable for engineers to estimate the contact strength in the fatigue analysis.

Research

Growing ecological and economic pressure leads to ever higher and more complex stresses in the development of plain bearings. The research at the institute is therefore primarily concerned with the investigation and development of alternative sliding materials and the influence of geometric deviations. The main focus of the investigations is the wear behavior under the most varied operating conditions (particles, mixed friction, hydrodynamics).
The permissible loads of selected WNV (tapered and cylindrical interference fit as well as feather key, knurled, polygonal joints, etc.) have been investigated primarily at IKAT for decades in the area of fatigue, fatigue and fatigue strength. The behavior under individual loads (bending, torsion) as well as combined dynamic loads is analysed.
In contact with various components, deformations in connection with the prevailing joint pressure initiate the damage process of fretting fatigue. Current research activities at the institute focus on basic research on the damage phenomenon of fretting fatigue and pursue the objective of developing an impact-compliant calculation method.
While conventional mechanisms owe their deformability to the sliding or rolling interfaces in the joints, flexible mechanisms fulfill their function through elastic stretches in places that are deliberately designed to be flexible during design. This functional principle enables novel, shape-adaptive structures, which can be used, for example, in softrobotics or in variable-shape wings. The professorship focuses its research on optimization-based synthesis methods.
The strength tests focus on the tooth root load-bearing capacity of worm gear units. The challenge to numerical imaging lies in the complex geometry and the special material bronze.
The coefficient of static friction (also: coefficient of friction or coefficient of friction) is to be understood as a system variable with a multitude of influencing parameters. In order to use existing potentials in friction-locking connections (e.g. screw, flange, press-fit connections), an experimental investigation is indispensable. With the help of standardized test methods on model samples, a wide variety of tribological configurations are examined at the research centre with regard to their transmission behavior. A major field of research is the synthesis of new design/selection tools for friction-enhancing measures (e.g. micro/laser structures, hard particles, coatings) for static and dynamic load cases.