Poor grades in courses related to my PhD thesis. Is that an indication to my research and future academic career potential? My PhD research will be in numerical modeling of Selective laser melting (SLM) process. I will be using finite element method, Fortran and python programming and a bit of machine learning in my research. My research is going to be completely computational based. I will be using Abaqus finite element analysis software for my research.

I took three courses (Finite Element Analysis, Mechanical behavior of materials and Numerical methods in scientific research) as part of my grad school requirements. I have a background in metallurgical engineering.

Now, I have got B-, A-, B+ grades in the three courses respectively. And I had worked hard for these courses, probably should have worked harder. My advisor says the grades and courses are a formality and I should focus on my research as I will learn more by doing than through any coursework.

It's true that I won't be developing any finite element code for my research and I will learn programming and fundamentals of material behavior as I go about my research, I am concerned that the abysmal grades in the courses is an indication to my research and future academic career inability. Is it? Any advice?
My advisor says the grades and courses are a formality and I should focus on my research as I will learn more by doing than through any coursework.


Your advisor is right.  Listen to him.  Class in an engineering Ph. D. program mean very little.  Research is more important by an order of magnitude.