SBIR-STTR Award

In response to NASA’s topic T12.02 of “Extensible Modeling of Metallurgical Additive Manufacturing Processes”, Sentient proposes to incorporate its DigitalClone technique to develop a multiscale and multiphysics computational modeling suite to predict comprehensive outcomes from AM building processes, including geometrical accuracy, and resulting microstructure and defects. Figure 1 shows the proposed framework for the multiscale modeling suite. The process model will first predict the microscale thermal evolution in respect of various parameters. The temperature results will feed a subsequent macroscale model for prediction of stress and distortion at part scale. Moreover, the predicted thermal history and distribution will feed subsequent microstructure model to further predict the micro-scale features including grain morphology and porosity. The proposed computational modeling framework allows a comprehensive prediction and understanding of the metal AM process at multiple levels. In Phase I, Sentient will upgrade and demonstrate DigitalClone’s capability to integrate process-microstructure simulation for metal AM process. Specifically, selective laser melting of IN 718 alloy will be used for development and demonstration purposes in Phase I. AM coupons with different geometries will be fabricated by Selective Laser Melting (SLM) at different parameters. DigitalClone will be used to simulate all different scenarios of coupons made from IN718 alloys, and predict temperature, stress, part distortion, and grain structure. Materials characterization will be performed on the coupons to examine geometrical accuracy, microstructure, residual stress, all of which will be used to validate the DigitalClone model. In Phase II, different materials and AM platforms and more complex geometrical components will be tested for model validation. Additionally, close-loop optimization framework will be explored for improving geometrical design and microstructure features. Potential NASA Applications A successful completion of this project will lead to a robust AM modeling suite that provides accurate prediction of dimensional accuracy, microstructure, and defects in AM process. The proposed modeling suite will significantly reduce the uncertainty and conservatism in design of new AM components and processes. NASA would directly benefit from this software via virtually pre-testing the new AM component design, process effects and part quality. Potential Non-NASA Applications The proposed modeling software will benefit several other industries incorporating AM technique, including aerospace, medical device, automotive industries. This will not only allow customers virtually evaluating the AM part qualities, more importantly, it will provide the “best solution” for customer in respect of optimizing AM design, selecting process and materials, increasing performance, reliability and durability, and reducing cost of operation the process.

In the Phase I period, Sentient upgraded its DigitalClone for Additive Manufacturing (AM) technology and successfully demonstrated and validated its “Process model” and “Microstructure model” for simulating metal AM processes. Sentient has partnered with University of Nebraska – Lincoln for model validation. Specifically, Sentient has implemented a new “Process model” to predict part-level residual stress and distortion for parts built using AM processes. The new model shows high simulation efficiency and accuracy. In addition, Sentient has improved the simulation speed of its “Microstructure model” by 100% for predicting the grain structure and porosity. The proposed DigitalClone for Additive Manufacturing (DCAM) simulation suite will fill the technical gap NASA is currently facing, and meet NASA’s requirement very well. The proposed solution allows NASA to: 1) simulate the part-level distortion and residual stress with respect to various key process parameters; 2) simulate the microstructure of as-built AM components with respect to key parameters and locations of interest; and 3) simulate the fatigue performance of as-built AM components at specific mechanical loading conditions. This physics-based simulation suite has been well demonstrated in different AM platforms (i.e. powder bed fusion and direct energy deposition) and several alloys systems that NASA is interested in. Those materials include Inconel 625, Inconel 718, 17-4 PH, 15-5 PH stainless steel, Ti64, and AlSi10Mg alloy. Additionally, the simulation suite can be applied to any new alloy with minimum calibration needed. This physics-based simulation suite directly benefits NASA via allowing computational testing for new component design, new materials, and new process, which will significantly reduce cost and time compared to conventional physical testing. In the Phase II effort, Sentient will focus on developing of prototype software and further validating different materials and components. Potential NASA Applications (Limit 1500 characters, approximately 150 words) NASA is currently on a path to implement additive processes in space flight systems. The technology developed under this STTR will help NASA to successfully build components (e.g. MOXIE, SHERLOC, ion engines and other spacecraft structural) using additive manufacturing process at minimal cost and time. Relevant personnel in NASA Jet Propulsion Laboratory (JPL) have showed a strong interest in using the developed technology. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) The proposed software module will enable designers, AM suppliers, and operators/purchasers of AM components to expand their implementation of their strategies to take advantage of AM technology. Our initial target list includes customers in aerospace and defense that have ongoing AM initiatives and have already expressed some level of interest in our physics-based solutions.