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

Mechanical engineering is the branch of engineering that designs, analyzes, builds, and maintains machines and systems that move, transmit force, or convert energy — engines, vehicles, HVAC and refrigeration plants, robots, medical devices, and the manufacturing equipment that produces them. It rests on applied physics and mathematics: statics and dynamics, thermodynamics and heat transfer, fluid mechanics, and mechanics of materials. 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.

In this guide: what the field studies and the four core subjects; what mechanical engineers do day to day; the main branches; how it relates to neighboring fields; who funds the research; the tools and methods used; and how education, FE/PE licensure, and ASME fit together, followed by a short FAQ.

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.

What mechanical engineers do

The U.S. Bureau of Labor Statistics describes the work as researching, designing, developing, building, and testing mechanical and thermal sensors and devices, including tools, engines, and machines. In practice a project usually moves through the same loop: analyze the problem and set requirements, model the design with computer-aided design (CAD), predict its behavior with simulation, build and test a prototype, investigate failures when something does not perform as expected, and then support the manufacturing process that produces it. BLS notes that mechanical engineers generally work in offices, with occasional visits to worksites where equipment needs their attention, and lists architectural and engineering services, machinery manufacturing, and transportation equipment manufacturing among the largest employers.

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. NSF’s CMMI page lists its core programs as Advanced Manufacturing, Design, and Operations; Engineering for the Built Environment; Foundational Research in Robotics; Intelligent and Interactive Dynamic Systems; and Mechanics of Advanced Materials Systems. 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.

BLS lists a bachelor’s degree in mechanical engineering or mechanical engineering technology as the typical entry-level education. ABET, the main accreditor in the US, accredits programs only, not degrees, departments, or institutions, so when checking a school the question to ask is whether the specific mechanical engineering program is accredited.

Professional licensure follows the same path as other engineering disciplines in the US: a degree from an accredited engineering program, a passing score on the Fundamentals of Engineering (FE) exam, relevant work experience (BLS says typically at least four years), and then a passing score on the Professional Engineer (PE) exam; both exams are administered by the National Council of Examiners for Engineering and Surveying (NCEES). NCEES describes the FE as computer-based, offered year-round at approved test centers, and designed for recent graduates and students close to finishing an EAC/ABET-accredited degree; passing it makes you an engineer in training or engineer intern. On the PE side, NCEES offers three separate Mechanical exams: HVAC and Refrigeration; Machine Design and Materials; and Thermal and Fluids Systems. 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), founded in 1880, 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.

Getting started. Strong preparation is calculus-based physics and mathematics; the early undergraduate years build the four core subjects above, with CAD, hands-on lab work, and internships or co-ops adding the practical side that employers look for. Taking the FE exam near graduation, while the coursework is fresh, is the first formal step toward a PE license for anyone who may eventually want one, and student or professional membership in ASME gives access to its codes, publications, and conferences.

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 do mechanical engineers do?

They design, develop, build, and test machines, engines, tools, and thermal systems, using CAD and simulation to predict performance, prototypes to test it, and failure investigation and manufacturing support to refine it. See the section on what mechanical engineers do above.

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.

How do you become a licensed mechanical engineer (PE)?

Earn a degree from an accredited engineering program, pass the FE exam, gain qualifying work experience (BLS says typically at least four years), and pass the PE exam in one of NCEES’s three Mechanical disciplines. Requirements are set by each state licensing board, so confirm yours with it.

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 fields

Mechanical engineering overlaps with many neighboring fields. Its thermal-fluid core connects it to chemical engineering and nuclear engineering, whose reactors and power systems depend on heat transfer and fluid flow. Flight vehicles are the territory of aerospace engineering, and fixed structures that of civil engineering. Feedback and automation draw on control theory and robotics; sensor-based vibration and condition monitoring lean on signal processing; component design depends on materials science; and the mechanics of living tissue and movement is the subject of biomechanics. For the parent discipline, see what engineering is.

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.