The SSA® (Scratch-Stress Analyzer) module is an easy-to-use software module of FilmDoctor® Studio which allows you to physically analyze any scratch test (adhesion test) including all measurement data provided by the test instrument. The SSA® module enables you to conduct a physical analyzis of scratch tests as it evaluates the distribution of 33 field components (e.g. von Mises stress, normal stresses, shear stresses, etc.) in the contact-stress field of the sample for each breakpoint of the scratch test and presents them as an animation. Thus, generic physical material properties such as critical stresses of all fracture modes can be determined exactly. Therefore, the Scratch-Stress Analyzer (SSA®) module does not only take into account simple material structures (e.g. monolithic samples), but also includes surface structures (e.g. superlattice coating systems with up to 100 layers, gradients etc.).
Additionally, the Scratch-Stress Analyzer module enables you to simulate scratch tests on potentially relevant surfaces (e.g. depending on surface roughness) and, hence, safes a lot for time of the experimental measurements. The required physical material parameters of the system can be determined by using our measurement analysis service, our software module OPfC®, or our Material DataBase.
Evolution of normal stress distribution (as cross section in scratch direction and depth) of a scratch test in a 1µm thick TiAlN coating on a rim hardened steel with a spherical indenter, 50µm radius, an initial normal load of 10mN, and end normal load of 100mN.
The features covered below are features of the model on which this product series is based. Therefore, they may differ from the capabilities of the individual editions as they are not all completely implemented in all editions.
Supported Material Structures
This module allows you to analyze among others the following surface structures by evaluation of mechanical contact measurements:
- multi-layer coatings (up to 100 layers)
- thin films (theoretically down to 1 angstroem*)
- thick films (theoretically unlimited*)
- with intrinsic/thermal stresses and gradients of it (functional)
- laminate structures
- nano-particle-enhanced coatings (nanotubes, fullerenes, …)
- inclusions and defects not only within layers but also at interfaces
- homogeneous monolithic bulk materials (e.g. substrate only)
Evolution of von Mises stress distribution of the above mentioned scratch test.
Among others, the following measurement conditions and measurement effects can be taken into account for the evaluation of mechanical surface measurements by this measurement analysis software module:
- multi-axial loads (normal, lateral, and rotating loads)
- tilting and deflection of the indenter
- actual indenter shape, hence also edges and asymmetry of indenter tips (e.g. required for Berkowich and Vickers tips)
- surface roughess, actual three-dimensional surface topography and surface curvature (e.g. from 3D pre-scan by AFM), respectively
- pile-up / residual stresses of ductile materials, plastic deformation, fractures/cracks of brittle materials
- temperature gradients / fields (e.g. necessary for high temperature measurements or tribology tests)
Evaluable Contact Measurements
The SSA®module enables you to analyze the following mechanical surface measurements:
- scratch tests, adhesion tests, and scratch resistance tests
- tribology tests like wear tests and friction tests (pin-on-disc, ball-on-disc and so on)
- also in high temperature range
- and many more
The most important aim of mechanical characterization is the evaluation of generic material properties, which are independent of measurement conditions (like material structure of the sample, initial and final load, velocity etc.). Hence, it is necessary to take all these measurement conditions into account to evaluate such a measurement properly. That is why we have developed a general analytic solution for all contact problems in the elastic regime. Thus, SSA® module is capable of calculating – among others – the following generic mechanical material properties:
- tensile strength
- adhesive strength
- critical stresses of all fracture modes (mode I crack, mode II crack, mode III crack)
Only these generic physical material properties can be reused in nearly any other surface structure (e.g. for surface optimization by means of modeling and simulation) without being obliged to repeat the characterization.
Connection to Measurement Equipment
The following measurement equipment manufacturers already provide a direct export interface to our software, which convert measurement data directly into our format:
- Anton Paar (formerly CSM Instruments)
- ASMEC GmbH – member of Zwick/Roell
Further manufacturers are still developing and will follow soon.
Our student Julius explains how to use the Scratch Stress Analyzer module in the FilmDoctor® software.
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