Mardoqueu M. Costa
Researcher in instrumentation and materials engineering
Postdoctoral researcher in Biosystems Engineering at ESALQ/USP (2023–2025) and holder of an Industrial Postdoctoral Fellowship from CNPq (Brazil's National Council for Scientific and Technological Development). PhD (2015) and MSc (2010) in Electrical Engineering from EESC/USP, bachelor's degree in Exact Sciences with a major in Physics from IFSC/USP (2008) and mechatronics technician from SENAI São Carlos.
Since 2005 he has worked in instrumentation, materials engineering and technology-based entrepreneurship, focusing on the development of scientific devices and equipment, mechanical testing of materials, and software for data acquisition, control and analysis. He has been a researcher at Biopdi since 2011, in the research and development laboratory, and was a professor and researcher at Universidade Brasil (Brazil) from 2017 to 2025, training students and researchers from undergraduate research to postdoctoral level.
He has published 22 journal papers, 3 book chapters, 36 full papers and 33 abstracts in conference proceedings, holds 3 patents, and has taken part in the development and commercialization of more than 26 products and 9 software packages. He runs research, development and innovation projects funded by the Brazilian agencies CNPq, FAPESP and Embrapii, and provides technical and scientific consulting.
This combination of equipment design and applied research is the foundation of the technical content published here: the tests described in the articles are the same tests that Biopdi equipment performs.
Education
- Luiz de Queiroz College of Agriculture (ESALQ/USP)
- São Carlos School of Engineering (EESC/USP)
- São Carlos Institute of Physics (IFSC/USP)
Professional registrations
Areas of expertise
Topics covered by the 102 articles published here.
- Mechanical testing of materials
- Universal testing machine
- Tensile test
- Compression test
- Flexural test
- Mechanical properties of materials
- Strain measurement (extensometry)
- Scientific instrumentation
- Materials science and engineering
- Development of testing equipment
- Data acquisition and control software
- Biomedical engineering
- Mechanical metrology
- Technology-based entrepreneurship
Articles (102)
ASTM D882: tensile testing of plastic films, strip specimen, test speed and secant modulus
ASTM D882-26 covers tensile testing of plastic films under 1.0 mm thick in 5 to 25.4 mm strips: speed, grips, secant modulus, example and D638 differences.
Destructive and non-destructive testing: differences, types and when to use each
Destructive tests break or mark the sample to measure properties; NDT finds cracks and pores without scrapping the part. Types and standards.
Test specimen: what it is, types by test and material, standards and dimensions
A test specimen is a sample whose shape and dimensions are set by the test standard. See types, standards and sizes for metal, plastic, concrete, wood and welds.
Axial-torsion test: combined tension and torsion, von Mises and standards
The axial-torsion test applies axial force and torque to the same specimen. See the tube stresses, von Mises, examples, ASTM E2207 and the machine.
Crush test: ECT, FCT, RCT and BCT
The crush test compresses corrugated board until it collapses. See ECT, FCT, RCT, CMT and BCT, formulas, McKee, 32 ECT in kN/m, standards and examples.
Fracture toughness testing (KIc): test, formula, standards and values
Fracture toughness (KIc) is the resistance to crack propagation. See the formula, the ASTM E399 test with a clip gauge, J, CTOD and typical values.
IFD test (ILD): indentation force deflection testing of foam
IFD (ILD) is the force for a 323 cm² indenter foot to compress foam by 25%. ASTM D3574 and ISO 2439 test, support factor, IFD vs CFD, density vs firmness.
Peel test: 90°, 180°, T-peel and peel strength calculation
The peel test measures the force per unit width needed to separate bonded materials. See 90°, 180° and T-peel, formula, units and ASTM and ISO standards.
Puncture resistance test: standards, methods and calculation
Puncture resistance test: the force and energy for a probe to pierce films, geomembranes, geotextiles and gloves. ASTM, ISO, EN standards and calculation.
Tear test: tear strength testing, standards and calculation
The tear test measures the force to start or grow a tear in rubber, film, fabric and leather. ASTM D624, ISO 34-1, D1938, D2261 standards and calculation.
Tensile tester: types, specifications and how to choose
How to choose a tensile tester: types, capacity, load cell, ISO 7500-1 class, grips, extensometer, cost and a quote checklist.
Bond test: mortar (NBR 13528), ceramic tile, paint and adhesives
The bond test measures the force to detach a coating, paint, mortar, tile or adhesive from its substrate. NBR 13528, NBR 13749, NBR 11003, pull-off, peel.
Torsion test: formulas, shear modulus G, fracture and standards
Torsion test: torque is applied to a cylindrical specimen and twist angle measured. Formulas (τ = T·r/J), shear modulus G, fracture, standards.
Toughness of materials: what it is, how to calculate it and units
Toughness is the energy a material absorbs before fracturing. Learn how to calculate it, units, the Charpy test, fracture toughness and reference values.
Universal testing machine: what it is, how it works and types
Universal testing machine (UTM): what it is, how it works, electromechanical and hydraulic types, tests, standards, calibration and how to choose.
Compression test: what it is, how to calculate it, concrete (NBR 5739 and fck) and standards
A compression test shortens a specimen until it fractures or yields. Learn to calculate compressive strength, plus NBR 5739, concrete fck and standards.
Atterberg limits: liquid limit and plastic limit
Atterberg limits per NBR 6459:2025 and NBR 7180:2025: how to calculate LL, PL and PI, the 25-blow plot, the plasticity chart and a worked example.
Mechanical strength: what it is, types, formula and values
Mechanical strength is the maximum stress a material bears before yielding or breaking (MPa). Types, formulas, tests, standards and values by material.
NBR 6457:2024: soil sample preparation and moisture content
ABNT NBR 6457:2024 guide: preparing soil samples for compaction and characterization, masses per test, and oven-dry moisture content with calculation.
Shear strength of soil: Mohr-Coulomb, cohesion and friction angle
Shear strength of soil: effective stress, the Mohr-Coulomb criterion, cohesion and friction angle, with typical values and 5 worked examples.
Soil compaction and the Proctor test per ABNT NBR 7182:2025
Soil compaction on site and the Proctor test per NBR 7182:2025: compaction energies, worked curve example, optimum moisture content and degree of compaction.
Soil particle size analysis: sieve and hydrometer test and gradation curve per NBR 7181
Soil particle size analysis per NBR 7181:2025: sieving, hydrometer sedimentation, gradation curve, D10, Cu and Cc, NBR 6502 fractions, worked example.
Strength of materials: concepts, formulas and examples
Strength of materials calculates stresses and strains in parts under load. See internal forces, formulas with units, worked exercises and books.
Resilient modulus (MR): what it is, how to calculate it and the repeated load test per Brazilian standards DNIT 134 and 135/2018
Resilient modulus (MR) is repeated deviator stress divided by recoverable strain in soils, aggregates and asphalt: MR = σd/εr, in MPa (DNIT 134, 135).
Triaxial test: what it is, UU, CU and CD types, calculations and standards
What the triaxial test is, what the name means, the UU, CU and CD types with their standards, the B parameter, the formulas and worked CU, UU and CD examples.
Marshall test: stability, flow, Vv, VMA (VAM) and VFA (RBV) per DNIT 447/2024-ME
The Marshall test measures the stability and flow of asphalt mixtures at 60 °C per DNIT 447/2024-ME. Procedure, Vv, VMA, VFA and a worked example.
Direct shear test: ASTM D3080 standard, step-by-step procedure and how to calculate c' and φ'
The direct shear test measures soil shear strength and gives the cohesion c' and friction angle φ'. ASTM D3080-23, step by step, with a worked example.
Consolidation test (oedometer test): procedure, Cc, σ'vm, cv and settlement per NBR 16853
Consolidation (oedometer) test per Brazilian NBR 16853:2020: measure Cc, σ'vm and cv in load-doubling stages, predict how much and how fast clay settles.
CBR test and the California Bearing Ratio
CBR test (California Bearing Ratio): NBR 9895:2025 and DNIT 172 standards, procedure, formula with 6.9 and 10.35 MPa, worked example and CBR by layer.
NBR 12142: flexural tensile strength of concrete prism specimens, calculation and examples
NBR 12142:2010 (in force): flexural tensile strength of concrete prisms under third-point loading. Formula, 5% rule, rate in kN/min and examples.
NBR 6136-2: compression test of concrete blocks, fbk, strength classes and what changed from NBR 12118
NBR 6136-2:2026 replaced NBR 12118 in Brazil: hollow concrete block tests, fb = F/Ab on gross area, fbk calculation, classes A, B and C, and what changed.
NBR 7222: splitting tensile test, fct,sp calculation, bearing strips and loading rate in kN/s
NBR 7222:2011 measures the tensile strength of concrete and mortar by diametral compression: fct,sp = 2F/(π·d·L) at 0.05 MPa/s. Strips, calculation, examples and machine.
Universal testing machine calibration: ISO 7500-1, classes, interval and certificate
Universal testing machine calibration per ISO 7500-1:2023: traceable standard, 3 series from 20 to 100%, classes 0.5 to 3, 12 months, certificate.
Weld test specimen: tensile and bend tests per ASME IX, AWS and ISO
Weld test specimen: how to cut, machine and run tensile and bend tests per ASME IX and ISO 15614-1, with the 3 mm and 95% criteria and examples.
NBR 15270-2: ceramic block and brick compression test, gross area, fbk, water absorption and IRA
NBR 15270-2:2023 tests for ceramic blocks and bricks: gross-area compression (fb = F/Ab), lot fbk, water absorption, IRA and the 2023 changes.
Extensometer and strain gauge: what they are, how they work, types and use in the tensile test
Extensometer and strain gauge: the bonded strain sensor (ΔR/R = GF·ε, GF ≈ 2), bridges, rosettes and the tensile test extensometer with ISO 9513 classes.
Load cell: what it is, how it works, types, accuracy class and the load cell of a testing machine
A load cell is the sensor that converts force into an electrical signal, typically 2 mV/V. How it works, types, 4- and 6-wire wiring and ISO 7500-1 class.
NBR 5739 concrete compression test: fc calculation and the NBR 7222, NBR 12142 and NBR 6136-2 standards
ABNT NBR 5739:2018 (the Brazilian standard for concrete compression testing), reaffirmed in 2023, covers compression testing of cylindrical concrete specimens: continuous loading at 0.45 ± 0.15 MPa/s until failure and fc = 4F/(πD²), in MPa, to three significant figures. See what it requires of the machine and the specimen, the h/d correction, failure types A to G and the related standards: NBR 7222 (splitting tensile test), NBR 12142 (flexural tensile strength) and NBR 12118, withdrawn in February 2026 and replaced by NBR 6136-2:2026.
Hooke's law: formula, graph and solved problems
Hooke's law: F = k·x for a spring, σ = E·ε for materials and the generalized 3D form. Formula, graph, experiment, 7 solved problems and a simulator.
Bend test: what it is, types, rebar, welds and standards (ISO 7438)
The bend test bends a specimen around a mandrel to 90° or 180° and checks for cracks. See test types, NBR 7480 mandrels, weld bend testing and standards.
ASTM A370: mechanical testing of steel products (tensile, bend, hardness and Charpy), annexes and how it relates to E8
ASTM A370-26: mechanical testing of steel products (tensile, bend, hardness, Charpy), product annexes, Charpy criteria and how it differs from E8.
ASTM D3039: tensile testing of composites, tabbed test specimens, chord modulus and failure modes
ASTM D3039 tensile test of polymer matrix composites: tabbed specimens, chord modulus from 1,000 to 3,000 µε and the failure code.
ASTM D412 and ISO 37: rubber tensile test, test specimens, speed and calculations
ASTM D412 and ISO 37 rubber tensile test: dumbbell or ring at 500 mm/min, tensile strength, elongation at break and stress at 100% and 300%.
ASTM D695: compression testing of rigid plastics (test specimen, 1.3 mm/min and calculations)
ASTM D695-26 measures compressive strength, yield and modulus of rigid plastics: a 12.7 × 12.7 × 25.4 mm prism at 1.3 mm/min. Calculations and ISO 604.
Brinell hardness test: HBW formula, ball, load and the ISO 6506-1 and ASTM E10 standards
The Brinell hardness test presses a 1 to 10 mm carbide ball into the metal and calculates HBW from the indentation area. Formula, scales and ISO 6506-1.
Rockwell hardness test: how it works, HRC and HRB scales and ISO 6508-1
Rockwell hardness test: permanent indentation depth becomes HR = N − h/S. HRC and HRBW scales, ISO 6508-1:2023, and what hardness does not measure.
Shear modulus (G): what it is, formula, relationship with E and ν, values and how to measure it
Shear modulus (G): the τ/γ ratio in the elastic range, 77 GPa for steel per NBR 8800. G = E/[2(1+ν)], values by material, measured by torsion.
Vickers hardness test and microhardness: HV formula, force ranges, case depth profile and conversion to HRC
Vickers and microhardness testing: HV = 0.1891·F/d², ISO 6507-1:2023 force ranges, case depth profile at 550 HV, HRC conversion and what hardness can't tell you.
ASTM D638: tensile testing of plastics, Type I to V specimens, test speed and calculations
ASTM D638-22 is the ASTM method for the tensile properties of plastics up to 14 mm thick, using Type I to V dumbbell specimens. See dimensions, test speed, conditioning, extensometer, formulas, a worked example and the differences from ISO 527-2:2025.
ASTM D790: three-point flexural test of plastics (procedures A and B, support span and calculations)
ASTM D790-25 measures the flexural strength and flexural modulus of plastics using a bar on two supports loaded at midspan. The support span is 16 times the thickness. The strain rate is 1%/min (procedure A) or 10%/min (procedure B), and the test runs until the specimen breaks or reaches 5% strain. Covers the crosshead speed R = ZL²/6d, the formulas, the large-deflection correction, a comparison with ISO 178 and D6272, and worked examples.
ASTM E8 vs ISO 6892-1: tensile testing of metals, differences and requirements (NBR ISO 6892-1 and A370)
ASTM E8/E8M-25 and ISO 6892-1:2019, adopted in Brazil as ABNT NBR ISO 6892-1:2024, cover the same tensile test of metals at room temperature. They differ in the specimen gauge length (4D in E8, 5D in E8M and 5.65√S0 in ISO), in speed control and its tolerance, in symbols, in rounding and in the standards for the machine and the extensometer. For that reason, elongation from one cannot be compared directly with elongation from the other.
Concrete test specimens: 10x20 and 15x30 cm cylinders and prisms, molding and curing (NBR 5738), how many to cast and testing
Concrete test specimens: 10 × 20 or 15 × 30 cm cylinders or prisms, molded and cured per NBR 5738, tested at 7 and 28 days. Rodding, curing, how many.
Yield strength: what it is, how it is measured (ReH, ReL, Rp0.2) and values for 1020, 1045, 4140, A36 and CA-50 steel
Yield strength is the stress at which a metal starts to deform plastically (ReH, ReL, Rp0.2). Standard minimums and values for 1020, 1045, 4140, A36, CA-50.
NR-12 for testing machines: what Brazil's machinery safety standard requires of a universal testing machine
The universal testing machine (UTM) falls under NR-12 (Brazil's regulatory standard for machinery and equipment safety): it is not among the exclusions in item 12.1.4, and it presents crushing, flying fragment and stored energy hazards. The current text is the one set by Ordinance SEPRT 916/2019, last amended by Ordinance MTE 344/2024 (Brazilian government ordinances). See the items that apply (12.5.1, 12.5.2, 12.5.6, 12.6, 12.11, 12.13 and 12.16), risk assessment under ISO 12100 (ABNT NBR ISO 12100 in Brazil), category and PL under ISO 13849-1 (NBR ISO 13849-1 in Brazil), exercises and a checklist.
Tensile test: what it is, step by step, calculations and standards (ISO 6892-1)
A tensile test pulls a specimen axially to fracture to measure yield strength, UTS, modulus and elongation. Calculations, steps, standards and specimens.
ISO 898-1: bolt property classes (8.8, 10.9, 12.9), proof load and testing
ISO 898-1:2013 defines the property classes of carbon steel and alloy steel bolts, from 4.6 to 12.9, and the tests that verify them. See what each number means, the summary table, the stress area of an M12 (84.3 mm²), the breaking and proof loads in kN, the tests and how to choose the testing machine.
NBR 13279: flexural tensile and compressive strength of mortar (4 × 4 × 16 cm prisms), calculation and classification
ABNT NBR 13279:2005, the Brazilian standard for mortar strength testing, is current and was reconfirmed by ABNT in November 2023. It is Brazil's method for measuring the flexural tensile strength and the compressive strength of masonry and rendering mortars. 4 × 4 × 16 cm prisms are broken in 3-point bending over a 100 mm span at (50 ± 10) N/s, and the broken halves are tested in compression over 40 × 40 mm at (500 ± 50) N/s. Rf = 1.5·Ff·L/40³ and Rc = Fc/1,600, in MPa. See the procedure, the rejection criterion, a worked example, the classification under NBR 13281 and the force capacity the machine needs.
NBR 13818: canceled standard, what replaced it (NBR ISO 13006 and NBR ISO 10545) and the flexural test of ceramic tiles
ABNT NBR 13818:1997 (the former Brazilian standard for ceramic tiles) was canceled in December 2020 and replaced by ABNT NBR ISO 13006:2020 (specification, the Brazilian adoption of ISO 13006) and the ABNT NBR ISO 10545 series (test methods, the Brazilian adoption of ISO 10545). See the water absorption groups, the current definition of porcelain tile, the 16 parts of NBR ISO 10545 and the flexural test of NBR ISO 10545-4 with worked examples.
NBR 7480: requirements for CA-25, CA-50, CA-60 and CA-70 rebar steel, table and tests
ABNT NBR 7480:2024 (the Brazilian standard for steel bars and wires for reinforced concrete) sets the requirements for rebar: categories CA-25, CA-50, CA-60 and CA-70, minimum yield strength, fst/fy ratio, elongation, bend test, linear mass and sampling. The test methods come from ISO 6892-1 (ABNT NBR ISO 6892-1 in Brazil) for the tensile test and from ABNT NBR 17005 for the bend test.
Hardness test: types, procedure and standards (Brinell, Rockwell, Vickers and Shore)
A hardness test presses a standardized indenter into the part under controlled force and dwell time, then measures the indentation or its depth. See the types, the step-by-step procedure for each method, minimum thickness and spacing, hardness tester verification and standards.
Mechanical properties of materials: what they are, the main types, tests, standards and steel values
The mechanical properties of materials define how a material responds to forces: how much it deforms, whether it returns to its shape, how much load it carries, how much energy it absorbs and how it fractures. See each property with its unit, test and standard, the values for steel (NBR 8800, the Brazilian steel structures design standard; ASTM A36; CA-50, the Brazilian rebar grade), the pairs that are often confused and solved exercises.
Malleability: what it is, the most malleable metals, how it differs from ductility and how it is evaluated
Malleability is a metal's ability to undergo large plastic deformation under compression, by hammering, pressing or rolling, without cracking. See why metals are malleable, a sourced ranking, the difference from ductility, how it is evaluated in testing (compression, bend, Erichsen cupping, flattening), malleable cast iron and worked examples.
Sintering: what it is, powder metallurgy steps, temperature, density and testing of sintered parts
Sintering is the consolidation of a compacted powder by heating below the melting point, usually at 70 to 85% of the absolute melting temperature: diffusion forms necks between the particles and reduces porosity. It is not a heat treatment of steel in the classic sense. Fe-Cu-C sintered steel: 1,120 to 1,150 °C for 20 to 30 min and 6.8 to 7.2 g/cm³. See the steps, mechanisms, stages, liquid phase, porosity, testing to ISO 2738, ISO 3325 and ISO 2739, and solved exercises.
Annealing of steel: what it is, types, temperatures and effects on properties
Annealing is the heat treatment that heats the metal, holds it at temperature and cools it slowly, usually inside the furnace, to reduce hardness and internal stresses and restore ductility and machinability. In steel, full annealing austenitizes about 30 to 50 °C above Ac3, and the subcritical types stay below Ac1 (stress relief annealing at 550 to 650 °C, spheroidizing at 700 to 720 °C). See the types, temperatures, microstructure, effects with numbers and how to check the result.
Nitriding: what it is, processes (gas, plasma and salt bath), white layer, NHD and difference from carburizing
Nitriding is a thermochemical treatment that diffuses nitrogen into the steel surface below the austenitizing temperature, with no quenching: 495 to 565 °C for gas nitriding, 430 to 595 °C for plasma nitriding and about 570 to 580 °C in a salt bath. It forms a white layer of 10 to 20 µm on top of a diffusion zone of 0.1 to 0.6 mm, with 600 to over 1,000 HV depending on the steel. See the processes, the steels, how to measure the NHD per ISO 18203 and the comparison with carburizing.
Tempering steel: what it is, temperatures, hardness curve and temper embrittlement
Tempering is the reheating of quenched (hardened) steel below the critical temperature, usually between 150 and 650 °C, to trade part of the hardness of martensite for toughness and to relieve quenching stresses. See what happens in martensite, the temperature ranges, the hardness and impact curve of 4140 steel, the Hollomon-Jaffe parameter, the two types of embrittlement, temper colors and how to check the result.
Carburizing of steel: what it is, types, temperature, case depth and control
Carburizing is the thermochemical treatment that enriches the surface of a low-carbon steel with carbon, usually between 900 and 930 °C, before quenching and tempering. The part ends up with a 58 to 62 HRC surface and a tough core. See the types (gas, pack, liquid and vacuum), Harris's formula for time (about 0.63·√t mm at 925 °C), the steels used, the effective case depth at 550 HV per ISO 18203:2026, defects and solved exercises.
Heat treatment of metals: what it is, types, iron-carbon diagram and TTT curves
Heat treatment is the controlled heating and cooling of a solid metal to change its microstructure and, with it, hardness, strength and toughness, without changing the shape of the part. See the three stages, the iron-carbon diagram (eutectoid at 727 °C and 0.77% C), TTT and CCT curves, microstructures, the families of treatments, 6061-T6, how to choose the process and how to verify the result.
Work hardening: what it is, mechanism, Hollomon equation (n-value), annealing and how to measure it
Work hardening (strain hardening) is the strengthening of a metal by cold plastic deformation: yield strength, tensile strength and hardness go up, ductility goes down, and the modulus of elasticity does not change. Learn the dislocation mechanism, the percent cold work (%CW), the Hollomon equation and the strain hardening exponent n, its measurement per ISO 10275 and ASTM E646, annealing, and solved exercises.
Ultimate tensile strength (Rm): what it is, formula, graph, steel table and how to measure it
Ultimate tensile strength (Rm) is the engineering stress at the maximum force of the tensile test: Rm = Fm/S0. See the symbols, where it sits on the graph, how it differs from yield strength and fracture stress, the steel table with material condition, CA-50 (Brazilian rebar grade), breaking load, the estimate from hardness, and exercises.
Proportional limit: what it is, how it differs from the elastic limit and yield strength, and how to measure it
In strength of materials, the proportional limit is the highest stress at which stress and strain are still proportional: the end of the straight portion of the curve and of Hooke's law. See the ASTM E6 definition, how it differs from the elastic limit and Rp0.2, how to measure it with an extensometer, and worked examples.
Elastic limit and yield strength: what they are, the difference, formula, Rp0.2 and steel table
The elastic limit is the highest stress without permanent strain; yield strength is where plastic strain becomes measurable (ReH and ReL, or Rp0.2). See the formula, symbols, 0.2% offset, steel table, CA-50 and exercises.
Necking in the tensile test: what it is, when it starts, reduction of area Z and cup-and-cone fracture
Necking is the localized reduction in cross-section of the test specimen that begins at maximum force in a tensile test. See Considère's criterion, the reduction of area Z = (S0 − Su)/S0 × 100 per ISO 6892-1, values by material, cup-and-cone fracture, the Bridgman correction, cold drawing of polymers and worked examples.
Resilience of materials: modulus of resilience, formula Ur = σe²/2E, units and difference from toughness
Resilience is a material's ability to absorb energy when it deforms elastically and to release it on unloading. See the modulus of resilience (Ur = σe²/2E), its derivation, the J/m³ unit, calculated values by material and condition, the difference from toughness, spring materials, the resilient modulus of pavements and solved exercises.
Quenching steel: what it is, temperatures, quenching media, types and the quench and temper cycle
Quenching steel means heating the part until austenite forms, usually 30 to 50 °C above Ac3, then cooling it rapidly in water, oil, polymer or gas to form martensite. Carbon sets the maximum hardness and alloying sets the hardened depth. See temperatures by steel (1045 at 820 to 850 °C), the Grossmann H severity, martensite and Ms, the Jominy test, types of quenching, stainless steel, cracking and the quench and temper cycle.
Elastic and plastic deformation: what elastic deformation is, formula, difference and examples
Elastic deformation is the reversible deformation of a solid: the bonds between atoms stretch without breaking, and the part returns to its original size when the load is removed. See the formula ε = σ/E, where elastic deformation ends, how it differs from plastic deformation, how much each material deforms, resilience, elastic recovery, rubber and solved exercises.
Plastic deformation: what it is, mechanism, formulas, metal forming and exercises
Plastic deformation is the permanent change of shape that remains in a material after the load is removed. In metals it begins at the yield strength and occurs through the movement of dislocations. See the mechanism, the formulas (εp = ε − σ/E and true strain), cold and hot working, how to measure it in a tensile test, and solved exercises.
Normalizing steel (heat treatment): temperature, air cooling and how it differs from annealing and quenching
Normalizing steel is the heat treatment in which steel is heated above the upper critical temperature (Ac3, or Acm in hypereutectoid steel), held until it becomes austenite and cooled in still air. The result is a refined grain and fine pearlite, with more strength than in the annealed condition and much less hardness than in the quenched condition. 1045 steel is normalized at about 850 to 880 °C.
Poisson's ratio: what it is, formula, values for steel, concrete and soil, and how to measure it
Poisson's ratio (ν) is the negative ratio of transverse strain to longitudinal strain in a material under uniaxial load in the elastic range. See the formula, its relationship with E, G and K, the range from −1 to 0.5, the values for steel (0.3 per ABNT NBR 8800, the Brazilian steel structures design standard), concrete (0.2 per ABNT NBR 6118, the Brazilian concrete structures design standard), rubber and soils, how to measure it per ASTM E132, and worked examples.
Modulus of elasticity of concrete: NBR 6118 formula, table by strength class and NBR 8522-1 test
The modulus of elasticity of concrete measures how much it shortens under load. Under NBR 6118:2023 (the Brazilian standard for the design of concrete structures), Eci = αE·5600·√fck (C20 to C50) and Ecs = αi·Eci. A C30 concrete with granite aggregate has an Eci of about 31 GPa and an Ecs of 27 GPa. See the formula, the C20 to C90 table, the effect of the aggregate, the NBR 8522-1:2021 test (the Brazilian standard test method for the modulus of elasticity of concrete) and worked examples.
Modulus of elasticity of steel: 200 or 210 GPa, table by grade, units and temperature
The modulus of elasticity of steel ranges from 190 to 210 GPa: NBR 8800 (the Brazilian steel structures standard) adopts 200 GPa for structural steel and NBR 6118 (the Brazilian concrete structures standard) adopts 210 GPa for reinforcing bars. See the values for A36, 1020, 1045, 4140, CA-50 rebar and 304 stainless steel, the conversion to MPa, kgf/cm² and kN/cm², the effect of temperature, G and Poisson's ratio, how to measure it and worked examples.
Biodegradable polymers: what they are, types (PLA, PHA, PBAT, PBS, PCL, starch), standards and mechanical properties
Biodegradable polymers are plastics that microorganisms convert into CO₂, water and biomass, rather than simply breaking into fragments. Biodegradation depends on the environment: PLA reaches 90% in six months only under industrial composting. Learn the difference between biodegradable, compostable, bio-based and oxo-degradable, plus the types, standards, mechanical properties and how to test them.
Industrial engineering: what it is, the 10 ABEPRO areas, professional duties, salary in Brazil and tools
Industrial engineering (engenharia de produção in Brazil) is the engineering that designs, implements, operates and improves integrated production systems for goods and services, according to ABEPRO (the Brazilian Association of Production Engineering). See the 10 areas and 58 subareas defined by ABEPRO, the professional duties set by Confea Resolution 235/1975 (Brazil's Federal Council of Engineering), the course curriculum, the salary in Brazil according to Novo CAGED (the Brazilian formal employment registry) and the minimum wage under Brazilian Law 4.950-A, and the Lean, Six Sigma, PPC, MRP and OEE tools with worked examples.
Materials testing: what it is, types, destructive and non-destructive testing, standards and how to choose
Materials testing is the standardized procedure that measures the mechanical, physical, chemical or microstructural properties of a representative sample, or that inspects a part without damaging it. See the five families of tests, the difference between destructive and non-destructive testing, the test specimen, accreditation, the standards and how to choose the right test.
Types of materials: metals, ceramics, polymers and composites (properties, how to choose and how to test)
Engineering materials fall into four classes: metals, ceramics, polymers and composites. The first three differ in the type of chemical bonding, which explains stiffness, ductility and service temperature; composites combine two or more classes. See examples, typical properties with sources, the Ashby chart, how to choose and how to test each class.
Quality engineering: what it is, tools (SPC, Cp/Cpk, FMEA, MSA), standards and career
Quality engineering is the field that uses statistics, metrology and testing to design, measure, control and improve processes so that products meet their specifications. See the tools (SPC, Cp/Cpk, MSA, FMEA, Ishikawa, Pareto, PDCA) with worked examples, the standards in force in 2026 (ISO 9001:2026, IATF 16949, ISO/IEC 17025, ISO 10012), testing machine calibration and the career outlook with dated figures.
Civil engineering: what it is, what civil engineers do, fields, salary and materials testing
Civil engineering is the branch of engineering that plans, designs, builds and maintains buildings and infrastructure, such as roads, bridges, dams, ports and sanitation. In Brazil, the duties of a civil engineer are set out in Article 7 of CONFEA Resolution 218/1973 (CONFEA is Brazil's Federal Council of Engineering and Agronomy), and practicing the profession requires registration with a CREA (Brazil's Regional Council of Engineering and Agronomy). See the fields, the degree program, salaries in Brazil with a dated source, the minimum wage for engineers under Brazilian Law 4,950-A/66, and the tests on concrete, steel, mortar and soils.
Mechanical engineering: what it is, what mechanical engineers do, curriculum, professional duties and salary in Brazil
Mechanical engineering is the branch of engineering that designs, manufactures, tests and maintains machines, equipment, vehicles and thermal systems. In Brazil, the professional duties of a mechanical engineer are set out in Article 12 of CONFEA Resolution 218/1973 (CONFEA is Brazil's Federal Council of Engineering and Agronomy). The degree requires at least 3,600 hours over 5 years, and the legal minimum salary for a 6-hour workday is R$ 7,272.00 (Brazilian reais). See the fields of work, the curriculum, the role of mechanical testing in training and in industry, and salary data with a dated source.
Modulus of elasticity (Young's modulus): what it is, formula, units, table of materials and how to measure it
The modulus of elasticity, or Young's modulus (E), is the ratio of stress to strain in the linear elastic region, E = σ/ε, and measures a material's stiffness. See the formula, the units and conversions, a table of E for more than 20 materials, the relationship with G, K and Poisson's ratio, the tangent, secant and chord moduli, and how to measure it with an extensometer.
Materials engineering: what it is, what materials engineers do, degree, legal duties and salary
Materials engineering relates processing, structure, properties and performance of metals, polymers, ceramics and composites to select, develop, manufacture and test the right material for each use. See what a materials engineer does, the professional duties defined by Confea (Brazil's Federal Council of Engineering and Agronomy), the degree curriculum, where to study in Brazil, salaries reported in Caged (Brazil's formal employment registry) and the Brazilian minimum engineering salary set by Law 4.950-A/66.
Coefficient of friction: what it is, formula, table and test (ASTM D1894)
The coefficient of friction (μ) is the ratio of the friction force to the normal force between two surfaces. See the formula, static and kinetic friction, the inclined plane, a table of values, solved exercises and film testing per ASTM D1894 and ISO 8295.
Impact test: Charpy and Izod, test specimen, ductile-to-brittle transition and standards
The impact test breaks a notched test specimen with a pendulum blow and measures the absorbed energy in joules. Learn about Charpy and Izod, the ISO 148-1 test specimen, the ductile-to-brittle transition temperature, acceptance criteria and standards.
Stress-strain curve: how to read the diagram, key points, formulas and the true stress-strain curve
The stress-strain curve plots stress (σ = F/S0) against strain (ε = ΔL/L0) from a tensile test. Learn to read each point, the formulas, the true curve, Brazilian CA-50 rebar steel, concrete per ABNT NBR 6118 (the Brazilian concrete design standard) and solved exercises.
Creep test: what it is, creep curve, creep of steel and standards
Creep is deformation that grows over time under constant load. See the curve with its three stages, creep rate, Larson-Miller, and creep of steel, plastics and concrete.
Pull-out test: what it is, how it is done, calculation and standards
The pull-out test pulls an embedded element, such as an anchor, bar, soil nail or screw, until it is extracted. See the procedure, calculation, failure modes and standards.
Fatigue testing: S-N curve, fatigue limit, Goodman, Miner's rule and standards
A fatigue test applies cyclic loading to a specimen until failure to obtain the S-N (Wöhler) curve and the fatigue limit. See the cycle parameters, the effect of mean stress, Miner's rule, the standards and the machines.
Hardness of materials: what it is, scales and HRC, HB and HV conversion chart
Hardness is a material's resistance to localized plastic deformation. Types, scales, HRC × HB × HV chart, what 60 HRC means and steel hardness.
Mechanical testing: what it is, types, what each test measures and standards
Mechanical tests apply a controlled load to a test specimen and measure the material's response. See the types (destructive, non-destructive, static and dynamic), what each test measures, the standards and the machine for each one.
Ductility: what it is, how to calculate it, ductile vs. brittle materials and examples
Ductility is how much a material deforms plastically before it fractures. See the elongation and reduction of area formulas, ductile vs. brittle materials and real values.
Cupping test: Erichsen, Olsen, Swift, forming limit curve and standards
The cupping test measures how far a thin metal sheet can be cold formed before it cracks. See the Erichsen test (IE index), Olsen, Swift (LDR), the forming limit curve, the r and n values and the standards.
Shear test: what it is, how to calculate it, shear modulus and standards
A shear test measures the force that makes two parts of a material slide along a plane. See τ = F/A, single and double shear, modulus G, adhesives, composites and standards.
Flexural test: 3-point and 4-point bending, how to calculate flexural strength, and standards
In a flexural test, a bar supported at two points is loaded until it fails. Learn 3- and 4-point setups, flexural strength and modulus formulas, NBR 12142 and ASTM D790.