# A Comparative Analysis of 3D Software for Modeling Fatigue Crack Growth: A Review
## 2 Software
### Numerical-Based Approaches
#### 2.1.4 Lynx  
LYNX is a specialized 3D software developed specifically for analyzing fatigue crack growth. It provides a wide array of tools and functionalities to accurately simulate and assess crack behavior in various materials and structural elements [54; 55]. LYNX supports a broad range of geometric configurations commonly encountered in fatigue crack growth studies. Moreover, it incorporates an automatic transition feature that seamlessly models the progression of cracks, transitioning between surface or corner cracks and through cracks [56]. This capability proves especially valuable when investigating intricate crack growth scenarios with diverse initiation and propagation patterns. To ensure accurate representations of crack fronts and surrounding areas, LYNX employs advanced mesh generation techniques. These techniques combine spider web meshes, regular meshes, and transitional meshes to generate precise numerical simulations that efficiently depict crack propagation. It can simulate crack propagation under different loading conditions, including constant amplitude, variable amplitude, and random loading.  
LYNX offers numerous advantages for fatigue crack growth simulation, which can be summarized as follows:  
* The software also offers capabilities for analyzing crack closure, stress intensity factors, and crack growth rates. LYNX can integrate with a range of software commonly used in engineering, including CAD software for geometry creation, mesh generation software, and post-processing tools like ParaView or MATLAB.
* It also supports interoperability with structural analysis software such as ANSYS or Abaqus. LYNX 171 is the latest version of the software, which integrates with other software packages like ABAQUS for modeling fatigue crack growth.
* LYNX has been extensively validated through numerous studies and real-world applications. It has been successfully applied in various industries, including aerospace, automotive, and structural engineering, to analyze and predict fatigue crack growth behavior. Its accuracy and reliability have been demonstrated through comparisons with experimental data and benchmark problems [57; 58].  
Despite its versatility in fatigue crack growth analysis, it is essential to take into account the limitations of LYNX. Some of the limitations of LYNX are as follows:  
* Limited scope: LYNX is specifically designed for in-plane problems related to fatigue crack growth. It may not be suitable for analyzing out-of-plane or complex three-dimensional crack propagation scenarios [54; 59].
* Geometric configurations: While LYNX offers a comprehensive set of geometric configurations, including notched and unnotched plates, round bars, and bars with corner cracks, it may not cover all possible geometries. Users should check if their specific geometry is supported by LYNX before conducting their analysis.
* Material models: The range of available material models in LYNX for fatigue crack growth analysis may be limited. It is important to ensure that the selected material model accurately represents the behavior of the material under fatigue loading conditions.
* Integration limitations: While LYNX 171 integrates with other software packages like ABAQUS for modeling fatigue crack growth, there may be limitations or challenges in the integration process. Compatibility issues or difficulties in transferring models between different software platforms can arise.