Cladding Stress and Deformation Analysis System Based on ANSYS Secondary Development

Literature Overview

This study presents the development of a specialized numerical analysis system for cladding stress and deformation prediction, built upon ANSYS finite element analysis software through secondary development. The system integrates thermal-mechanical coupling analysis, material property databases, and welding process simulation capabilities to provide engineers with a practical tool for predicting residual stress distributions and deformation patterns in cladding operations. The motivation for this development stems from the increasing complexity of modern cladding applications—particularly in nuclear, petrochemical, and power generation industries—where the inability to predict deformation accurately leads to excessive machining allowances, rework, and quality failures.

System Architecture and Methodology

The developed system follows a modular architecture with the following key components:

1. Thermal analysis module: Simulates the transient temperature field during multi-pass cladding using a moving heat source model (Goldak double-ellipsoidal model for GTAW/GMAW, rectangular model for SAW). The thermal analysis employs adaptive mesh refinement to capture the steep thermal gradients near the fusion boundary.
2. Mechanical analysis module: Couples with the thermal results to compute residual stress and deformation using an elastic-plastic material model with kinematic hardening. The system accounts for phase transformation effects through the Q-T method for materials undergoing martensitic transformation.
3. Material database: Contains temperature-dependent material properties for common substrate and overlay materials including Q235, 16Mn, 304, 316L, Inconel 625, Hastelloy C276, and various CuNi alloys.
4. Post-processing and visualization module: Provides stress contour plots, deformation vector fields, and quantitative output of stress distributions at critical locations such as the fusion boundary, cladding layer surface, and weld toe.

Key Simulation Results

The study validates the system against experimental measurements from strain gauge and neutron diffraction studies. The following table summarizes the validation accuracy:

The system demonstrates that residual stresses in the cladding layer typically reach 60–80% of the material yield strength, with the highest tensile stresses concentrated at the fusion boundary and at the termination points of the cladding tracks. Deformation predictions show that cladding-induced distortion is primarily in the form of angular distortion at the cladding edge and longitudinal bowing along the cladding direction.

Engineering Applications and Process Optimization

The system has been applied to optimize cladding procedures for several industrial scenarios:

• Hydrogenation reactor cladding: Predicted deformation of 2.3 mm per meter of cladding length on a 25 mm thick 16Mn shell, informing the selection of a machining allowance of 3.0 mm.
• Heat exchanger tube sheet cladding: Identified asymmetric stress distribution due to the tube layout pattern, leading to the development of a symmetrical cladding sequence that reduced angular distortion by 45%.
• Spherical tank cladding: Demonstrated that the curvature effect amplifies residual stress by approximately 15% compared to flat plate simulations, necessitating the use of a 3D curved model rather than a simplified planar approximation.

Key Questions and Reflections

A significant limitation identified in the study is the simplification of the material model. The Q-T method, while widely used, does not fully capture the complex phase transformation behavior in dilution zones where multiple phases coexist. Additionally, the system assumes idealized heat source models that may not accurately represent the actual energy distribution in processes such as PTA cladding or laser cladding, where the interaction between the heat source and the molten pool is highly dynamic.

Another reflection concerns the computational efficiency. While the system provides accurate predictions, the computational time for large-scale models (such as full reactor vessel cladding) can be prohibitive. The study suggests that a hybrid approach—using detailed 3D models for critical regions and simplified 2D or axisymmetric models for less critical areas—could significantly reduce computation time while maintaining acceptable accuracy.

Study Insights and Implications

This literature represents a significant advancement in the computational tools available for cladding process design. The secondary development approach demonstrates that general-purpose FEA software can be effectively adapted for specialized welding applications, providing engineers with a powerful tool for process optimization before physical trials are conducted. The validation against experimental data confirms that the system achieves engineering-grade accuracy (within 10% deviation), which is sufficient for predicting deformation magnitudes and optimizing cladding sequences. For pressure vessel fabrication governed by ASME VIII Div. 2 or NB/T 47002, where deformation control is critical for dimensional accuracy and subsequent welding operations, this type of predictive tool can reduce rework costs and improve first-time quality. The system also supports the qualification process by providing the stress analysis documentation required for fitness-for-service assessments under API 579 or NB/T 20002. Engineers should consider integrating such numerical tools into their standard design workflow, particularly for complex geometries where analytical methods are insufficient.