I welcome and look for opportunities to extend and transfer high-profile computational modeling and machine learning tools into many engineering roles for case-specific numerical recipes and problem-solving.

Advanced Welding Engineering
  • Computational Weld Modeling and Simulation
  • Distortion Control Plan and Residual Stress Mitigation
  • Welding Residual Stress by the Contour Method Map
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    Fracture and Failure Analysis
  • Complex Fitness-for-Service under BS 7910 / API 579
  • Non-Planar 3D Crack Growth Analysis in Weld & HAZ
  • Fracture Load Calculation from the Fracture Surface
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    Machine Learning in Welding
  • Limited-Data Machine Learning for Engineering Application
  • Digitization of Welding and Digital Twins of Welded Structure
  • Autonomous Distortion Control Programming and Mitigation
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    Computational Engineering Training
  • Practical Weld Modeling and Simulation
  • Computational Fracture Analysis
  • Simulation-Based Fitness-for-Service
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    Digital Engineering

    Today’s engineering analysis cannot be a general discipline and we need a case-specific problem-solving skill to precisely compute large scale mechano-material effects using coupled physic-based algorithms on a case-by-case analysis in order to justify making right engineering decisions. When it comes to analysis and model of today’s complex problems, the complexity and interactive physics of governing constitutive equations make the use of existing software less successful. Buying a general modeling software, I believe, is now facing limitation for enabling our engineers to find a solution for our case-specific problems. My approach is to enable our engineers to develop applications by constructing physic-based numerical recipes to create, test and program an innovative computational application for our case-specific problems. This applies the new and rapidly growing multidisciplinary field called “Computational Engineering” in many fields of engineering that uses advanced computational methods and analysis to case-specific engineering practice. Computational engineers have extensive education and training in fundamental engineering and science, and advanced knowledge of mathematics, algorithms and computer languages. They use the computer and math algorithms to solve physics-based equations to make predictions and simulate scenarios for a variety of industries. Keep in mind, computational engineers are not a computer scientist or computer engineer, they are material or mechanical or civil engineers.

    Computational Welding Mechanics (CWM)

    The use of computational models is well established in many areas of engineering; and using the state of the art algorithm and platform for modeling and simulation tools enables our engineers applying their creativity, expertise, and skill to be optimal, more productive, and innovative when dealing with design for failure. However, the mechanics of weld is among few fields where design, control, and optimization remain generally traditional and not yet well advanced. We have done a good job of making a large variety of high strength materials and designed structures to tolerate failure such as fatigue, creep, rupture and so on. Yet, failure has been observed to occur in our structures after a relatively low in-service life and frequently reported in weld for a large portion of occurrences. The reason is because we are taking the mechanics of weld for granted in all discipline of engineering. Generally, the weld engineers rely on previous experience and the best practice of moment – a non-deterministic trial and error approach. That is why car’s safety is linked to weld resistance to rupture in the crash, and the degree of reliability is defined by the welds. New materials such as Aluminum, Magnesium, and High Strength Steels are now available to improve power-to-weight ratio in cars, however, their welding concerns prevent them yet from seeing them in our streets. Broken welds are the biggest cause of train derailments as of claim by the Federal Rails Transportation. Historically, weld issues has repeatedly delayed Bombardier Transportation manufacturing of new rail cars, as well as fatigue in existing rail cars are frequently reported on welds. Welding comprises a significant portion of shipbuilding where the weld is now the major challenge of shipyards around the world, for example, a 5 year-old MOL container ship broke into two from weld in HSLA steel in 2013. Early in 2016, hundreds of wonky welds kept two west coast submarines stuck in Canada’s Pacific port [CBC]. Although welding is the fastest method of fabrication, the use of welding in the aircraft industry has been restricted, in general, due to the lack of fully reliable welding. Fusion line fracture is a known problem of 3D printed products that are ranked highly prone to cracking in long term service condition under fatigue and creep. The pipeline, energy, oil and gas industries recognize weld as the most fragile bottleneck of manufacturing and fabrication. The controversial Kinder Morgan trans-mountain natural gas pipeline and many other similar environmental controversies are because of failure in weld, not the pipeline. If we believe the green projects are essential for our environment on one hand and the safety of our workforce and safeguarding public are our due diligence on another hand, Welding is the key manufacturing segment to reduce hazards to our environment and enhanced safety to the workforce and safeguarding the public. The bottleneck that is complex engineering in nature because the science of welding is complex and therefore not many experts would takes the challenge of delivering a perfect weld. I found it a big opportunity for a decade of my carrier path to explore this challenging discipline.

    Additive Manufacturing (AM)

    Recent advancement in manufacturing moves toward Additive Manufacturing (AM) and 3D printing of solid metallic components. Welding creates a metal pool on the surface of the part; a recent form of welding is depositing metal pool along a tool path and layer by layer to build a part from a variety of alloys. Laser welding which uses a focused laser beam as the heat source for depositing powdered metals, is frequently employed for Laser Deposition Technologies (LDT) which is a blanket name that encompasses many processes namely, Laser Additive Manufacturing (LAM), Direct Metal Laser Sintering (DMLS), Selective Laser Sintering (SLS), Direct Metal Deposition (DMD), Laser Metal Deposition (LMD), Laser Freeform Manufacturing (LFM), and others. The Boing Company has been utilizing LAM / SLS for flight hardware in regular production since 2002, for both military and commercial programs e.g 787. The process is vastly developed and machinery is widely available to build parts; however deposit quality and consistency, manufacturing mechanics and materials’ behavior are still challenging, also there is lack of comprehensive modelling on AM. The laser deposit has an extremely high cooling rate. These cooling rates generate different mechanical properties and microstructure features comparing to the traditional process, also micro-porosity has shown to be a critical parameter in fatigue life of AM parts. Oak Ridge National Lab (ORNL) has started using the largest ever solid 3D printing machine for Boeing 777x wing trim. ORNL is now completing verification testing and production is scheduled to begin in 2017 and first delivery is targeted for 2020. The science and engineering of 3D printing is essentially a guided welding head that deposits molten metal in a trajectory of geometry. The most frequent problem of 3D printing is warping (i.e. distortion in stacking direction), bulging (i.e. lateral distortion), first layers (i.e. discard), non-uniform shrinkage, and cracks in tall and thin objects. The development gap between production in 2017 and delivery in 2020 is on the welding science of 3D printing to solve these challenges using an optimal thermal delivery and building uniform microstructural features. Distortion and induced stress during the deposition process, which comes from the high gradient of temperature at the molten deposit, are old welding topics that are now maturing for the craft of digital production where predictive models of weld are coupled with sensors and control algorithm in real time for making a sound 3D printed product. For example, ongoing work on field-digital-production (rather than shop production) is a welding robot compensates the solidification rate of deposition to follow a trajectory in the mid-air for building a steel bridge fabrication in the city of Amsterdam. On the other side of the spectrum, Micro Additive Manufacturing of metals is now growing by means of a guided deposition through an electrochemical process to fabricate micron-size features and products. Power and availability of Laser go hand-to-hand with AM for Laser Additive Manufacturing (LAM) and Direct Metal Laser Sintering (DMLS) to create a capability for manufacturing parts of high integrity for the primary and secondary structure as well as performing critical and effective repair processes on existing damaged structures.

    Non-Destructive Crack Closure Engineering

    In-service internal crack is the principal cause of almost every mechanical failure in aircraft structure and hardware. Currently, the best safety practices attempt to minimize the risk of such disasters, but at very high costs. For example, a detailed economic analysis by Battelle showed that fracture costs $119 billion dollars per year in the USA alone, representing approximately 4% of the reporting year’s gross national product (GNP). Existing repair process of a damaged structure, for example in Bombardier, involves machining the surface to the crack location and subsequently reconditions it with new material deposition and machining. This is destructive and the state-of-the-art has no nondestructive technique. I introduced a novel nondestructive concept to weld and close internal cracks. The main advantage of my technique over current technology is that it is “nondestructive” which is highly desirable and attractive for the industry as opposed to the current methods that require machining of the material to the crack location and then re-conditioning it. With the new technique, there will be no side damage from typical repair processes and down-times will be significantly reduced, minimizing expenses and the number of human resources required to implement the process. However, this novel technology is in its initial stages and needs further development and validation in terms of the evolution of material-mechanical characteristics, time and space dependency, process optimization and control as well as employment in a variety of applications. There exists a high potential for patents, publications, and conference presentation as well as interactive collaboration with industry ranging from high-end to routine engineering that suffers from the high cost of crack failures.

    Paper Under Progress

    1. Mahyar Asadi, Ghazi Alsoruji, John Goldak, `` Exploring Sequential Combinatorial Weld Sequence for Minimal Welding Distortion in Panel Structures Using a Limited Number of Welding Simulation Analysis”, Journal of science and technology of welding & joining. Under Progress, TBD.

    2. Mahyar Asadi, Jun Zhao, Avi Banerjee, Ashok Koul, Lejun Li, `` A Coupled Computational Welding Mechanics and Physics-Based Damage Modeling for Prediction of Remaining Useful Life in Welded P91 Alloy”, J Materials Science and Engineering: A, Elsevier. Under Progress, TBD.

    3. Mahyar Asadi, Dominic Guillot, Arnaud Weck, Subray R. Hegde, Ashok K. Koul, Trevor Sawatsky, Henri Saari, Ahmad Chamanfar, Mohammad Jahazi, ``A Validated Creep Deformation Mechanisms Map using Low-Temperature Creep Strain Accommodation Processes for Alloy 718, A Nickel-Base Superalloy”, J of Engineering Failure Analysis, Elsevier. Under Progress, TBD.

    4. Mahyar Asadi, Mischael Raj, Julio Angel Infante Sedano, Abdolmajid Mohammadian, Ousmane Seidou, Arnaud Weck, ``Studying an Economical Solar Selective Coating for Parabolic Trough Solar Thermal Technology”, Journal of Renewable energy, Elsevier, 10 pages, Under Progress, TBD.