What Is Mechanical Engineering? Research Areas, Funding, and Career Paths

Mechanical engineering is the branch of engineering concerned with the design, analysis, manufacturing, and maintenance of mechanical systems — anything that involves motion, forces, energy conversion, or the physical behavior of materials under load. It rests on a common core of applied physics and mathematics: statics and dynamics (how forces act on bodies at rest and in motion), thermodynamics and heat transfer (how energy moves and converts between forms), fluid mechanics (how liquids and gases behave and exert forces), and mechanics of materials (how solid objects deform, bend, and fail under stress). Mechanical engineers apply these principles to design, build, and maintain machines, engines, vehicles, HVAC and refrigeration systems, robots, medical devices, and the manufacturing processes that produce them — in short, almost any system with moving parts or that has to manage energy and forces. It is one of the oldest and broadest engineering disciplines, and its core coursework underlies large parts of aerospace, automotive, energy, robotics, and manufacturing engineering.

What mechanical engineering actually studies

At its core, mechanical engineering asks a small set of recurring questions about any physical system: How will this component or structure behave under load, and when will it fail? How efficiently can this system convert one form of energy into another (fuel into motion, electricity into heat, wind into rotation)? How will fluids and gases move through or around it? How can it be manufactured reliably and economically, and how will its parts interact, wear, and degrade over time? Answering these questions draws on four foundational subject areas taught in essentially every mechanical engineering curriculum:

• Statics and dynamics — how forces and moments act on rigid bodies at rest and in motion, the basis for analyzing everything from a bridge truss to a rotating engine crankshaft.
• Thermodynamics and heat transfer — how energy moves and converts between forms, and how heat is generated, transferred, and dissipated in engines, power plants, and electronics.
• Fluid mechanics — how liquids and gases flow and exert forces, central to everything from aircraft aerodynamics to pump and pipeline design.
• Mechanics of materials — how solid materials deform, bend, fatigue, and ultimately fail under mechanical stress, which governs how components are sized and selected.

Methodologically, mechanical engineering is applied rather than purely theoretical: problems are typically solved through a combination of analytical modeling, computational simulation, and physical testing, with an explicit design-build-test cycle that distinguishes it from adjacent basic-science fields.

Major sub-disciplines within mechanical engineering

Mechanical engineering has grown broad enough that most practitioners specialize. The major sub-disciplines include:

• Solid mechanics and structural analysis — stress, strain, deformation, fatigue, and failure analysis of load-bearing components and structures.
• Thermal-fluid sciences — applied thermodynamics, heat transfer, and fluid mechanics, including HVAC, refrigeration, and combustion systems.
• Dynamics, vibrations, and controls — the motion of mechanical systems over time, vibration and acoustics, and the feedback control systems that regulate machine behavior.
• Design and manufacturing engineering — machine design, computer-aided design and manufacturing (CAD/CAM), production processes, tolerancing, and quality engineering.
• Mechatronics and robotics — integrating mechanical systems with sensors, actuators, electronics, and control software, an area that overlaps heavily with electrical engineering and computer science.
• Energy systems — power generation, propulsion, renewable-energy conversion (wind turbines, solar-thermal systems), and energy storage.
• Biomechanical engineering — applying mechanical-engineering principles (statics, dynamics, materials behavior) to biological tissues, prosthetics, orthopedic implants, and medical devices; this sub-discipline shares substantial common ground with the study of human movement covered in CASRAI’s guide to kinesiology.
• Tribology — the study of friction, wear, and lubrication between surfaces in relative motion.
• Materials engineering — selecting, processing, and characterizing the materials (metals, polymers, composites, ceramics) that mechanical designs depend on, an area that overlaps directly with materials science.

How mechanical engineering relates to neighboring disciplines

Mechanical engineering sits at the center of a dense web of related engineering and physical-science fields, and the boundaries between them are more about emphasis than hard divisions. It shares its thermodynamics and fluid-mechanics core with chemical engineering, which applies those same principles to chemical process design rather than machine design. It shares structural-mechanics methods with civil engineering, though civil engineering applies them chiefly to buildings, bridges, and infrastructure rather than machines — see CASRAI’s guide on what civil engineering is for that distinction in detail. It overlaps heavily with electrical engineering in mechatronics, robotics, and control systems, where mechanical hardware and electronic control merge — see CASRAI’s guide on what electrical engineering is. Historically, aerospace engineering grew directly out of mechanical engineering departments and still shares its core thermodynamics, structures, and fluid-dynamics coursework. And where mechanical principles are applied to biological systems and medical devices, mechanical engineering shades into biomedical engineering. For how mechanical engineering fits within engineering as a whole, see CASRAI’s parent guide on what engineering is.

Who funds mechanical engineering research

In the United States, mechanical engineering research is funded predominantly by federal agencies, supplemented by substantial industry R&D investment in applied areas. The main public funders are:

• National Science Foundation (NSF) — the primary funder of fundamental mechanical-engineering research, chiefly through its Directorate for Engineering (ENG). Within ENG, the Civil, Mechanical and Manufacturing Innovation (CMMI) division funds core mechanical-engineering territory — manufacturing, machine design, robotics and controls, materials and structures, and infrastructure resilience — while the Chemical, Bioengineering, Energy and Transport Systems division funds thermal-fluid and energy-conversion research with mechanical-engineering relevance.
• Department of Energy (DOE) — the Office of Energy Efficiency and Renewable Energy (EERE) funds applied research in energy systems, propulsion, and industrial efficiency; the Office of Science’s Office of Basic Energy Sciences funds more fundamental materials and thermal-science research that underlies mechanical engineering. See CASRAI’s guide on writing a DOE Office of Science grant proposal narrative and its comparison of ARPA-E and DOE Office of Science funding.
• NASA — funds mechanical-engineering research with aerospace relevance: propulsion, structures, thermal-control systems, and materials for flight applications.
• Department of Defense (DOD) — the Office of Naval Research (ONR), Army Research Office (ARO), and Air Force Office of Scientific Research (AFOSR) fund mechanical-engineering research with defense applications (structures, propulsion, materials, autonomous/robotic systems), and DARPA funds higher-risk, more applied mechanical and robotic systems research. See CASRAI’s overview of the DOD research funding landscape.
• National Institutes of Health (NIH) — a much smaller funder of mechanical engineering specifically, but relevant where the field intersects biomedical research: the National Institute of Biomedical Imaging and Bioengineering (NIBIB) funds biomechanics and medical-device engineering research.

Beyond federal funding, a substantial share of applied mechanical-engineering research and development happens inside industry itself — automotive, aerospace, energy, and manufacturing companies fund significant internal and university-partnered R&D, which is a distinguishing feature of mechanical engineering relative to more purely federally-funded basic-science fields.

Research methods, tools, and equipment

Mechanical engineering research and practice combine computational modeling, physical experimentation, and increasingly data-driven analysis:

• Computational modeling — computer-aided design (CAD) for geometry and assembly modeling; finite element analysis (FEA) for simulating stress, deformation, and heat transfer in structures; computational fluid dynamics (CFD) for simulating fluid and thermal behavior; and multibody dynamics simulation for systems with moving, interacting parts.
• Physical testing and instrumentation — universal testing machines for tensile and compression testing of materials; wind tunnels for aerodynamic testing; vibration shakers and accelerometers for dynamics and vibration studies; strain gauges, thermocouples, and pressure transducers for instrumenting physical prototypes; and high-speed cameras for capturing rapid mechanical events.
• Manufacturing and prototyping — CNC machining and additive manufacturing (3D printing) for building physical prototypes and test articles, allowing rapid iteration between simulation and physical validation.
• Data-driven methods — an increasing share of mechanical-engineering research applies sensor-based condition monitoring and machine-learning techniques to problems like predictive maintenance, design optimization, and materials discovery, alongside the field’s traditional analytical and experimental methods.

Careers and training in mechanical engineering

The standard entry credential for practicing mechanical engineering is a bachelor’s degree from an ABET-accredited mechanical engineering program, which most US employers and licensing bodies expect as a baseline. Graduate study follows the same general structure common across engineering and the physical sciences: a master’s degree typically combines advanced coursework with either a research thesis or a non-thesis project option, while a PhD program layers original dissertation research — usually including qualifying/candidacy exams and a defended dissertation — on top of an initial period of coursework, and is oriented toward research careers in academia, national laboratories, or industrial R&D.

Professional licensure follows the same path as other engineering disciplines in the US: candidates typically pass the Fundamentals of Engineering (FE) exam, gain several years of qualifying work experience, and then pass the Professional Engineer (PE) exam, both administered by the National Council of Examiners for Engineering and Surveying (NCEES). A PE license is generally required for engineers who offer services directly to the public or sign off on designs affecting public safety, though many mechanical engineers in industry roles (automotive, consumer products, aerospace) practice without one. The American Society of Mechanical Engineers (ASME) is the field’s principal professional society — it publishes widely used engineering codes and standards (including the ASME Boiler and Pressure Vessel Code), technical journals, and professional-development and certification programs.

Mechanical engineers work across an unusually wide range of industries: automotive, aerospace, energy and power generation, industrial and consumer manufacturing, robotics and automation, HVAC and building systems, and medical-device development, in addition to academic and national-laboratory research roles.

Frequently asked questions

What is mechanical engineering in simple terms?

Mechanical engineering is the engineering discipline focused on designing, analyzing, and building things that move or manage energy — machines, engines, vehicles, HVAC systems, and manufacturing equipment — using the core principles of statics and dynamics, thermodynamics, fluid mechanics, and materials behavior.

What are the main branches of mechanical engineering?

The major sub-disciplines are solid mechanics and structural analysis, thermal-fluid sciences, dynamics/vibrations/controls, design and manufacturing engineering, mechatronics and robotics, energy systems, biomechanical engineering, tribology, and materials engineering.

Who funds mechanical engineering research?

In the US, the main federal funders are the National Science Foundation (particularly its Directorate for Engineering, through the CMMI division), the Department of Energy (EERE and the Office of Basic Energy Sciences), NASA, and Department of Defense research offices (ONR, ARO, AFOSR, DARPA), with NIH’s NIBIB funding the biomedical-engineering overlap. Industry R&D also funds a substantial share of applied mechanical-engineering work.

Do you need a PE license to work as a mechanical engineer?

Not always. A Professional Engineer (PE) license, earned via the FE and PE exams administered by NCEES plus qualifying work experience, is generally required for engineers who offer services directly to the public or certify designs affecting public safety. Many mechanical engineers working in industry (automotive, consumer products, aerospace) practice without a PE license.

What is the difference between mechanical engineering and civil engineering?

Both rely on structural-mechanics principles, but mechanical engineering applies them chiefly to machines and moving mechanical systems, while civil engineering applies them chiefly to fixed infrastructure — buildings, bridges, roads, and water systems. See CASRAI’s guide on what civil engineering is for more detail.

What is the difference between mechanical engineering and electrical engineering?

Mechanical engineering focuses on mechanical systems, motion, and energy conversion involving physical forces and materials, while electrical engineering focuses on electrical systems, circuits, and electromagnetic phenomena; the two overlap substantially in mechatronics and robotics. See CASRAI’s guide on what electrical engineering is.

What degree do you need to become a mechanical engineer?

A bachelor’s degree from an ABET-accredited mechanical engineering program is the standard entry credential. Research-oriented and advanced design roles typically require a master’s or PhD, following the same coursework-plus-thesis (MS) or coursework-plus-dissertation (PhD) structure common across engineering and the physical sciences.

Related CASRAI resources

Mechanical engineering is one of many major scientific and engineering disciplines covered in CASRAI’s overview guide to the branches of science, which maps how it relates to neighboring fields across the natural and applied sciences. For the broader parent discipline, see CASRAI’s guide on what engineering is; for closely related engineering fields covered in this same series, see CASRAI’s guides on civil engineering, electrical engineering, and — for the human-movement side of biomechanics — kinesiology. Mechanical engineering’s thermodynamics core is covered from the physics side in CASRAI’s guide on what physics is. On the funding side, see CASRAI’s guides to the DOD research funding landscape, writing a DOE Office of Science grant proposal narrative, and the comparison of ARPA-E and DOE Office of Science funding.