This book improves readers' ability to describe and implement a process for duplicating, reproducing, or repairing a work using reverse engineering. Certain regulatory guidelines related to reverse engineering are listed in this book for information only.
Historical Background
Industrial Evolution
Reverse engineering is a practice of invention based on knowledge and data obtained from earlier work. Reverse engineering plays a significant role in the aerospace industry mainly due to the following reasons: maturity of the industry, advancement of modern technologies and market requirements.
Reinvention of Engineering Marvels from Nature
However, the height of the first flight was about the same height as the flying birds. It also reflects one of the main goals of reverse engineering: to replace the original part.
Reverse Engineering in Modern Industries
Reverse engineering is the most effective way to recreate the component parts of this engineering marvel due to the lack of original design data. One of the widely cited examples of reverse engineering in the military is the Soviet Tupolve Tu-4 (Bull) bomber.
Reverse Engineering vs. Machine Design
Motivation and Challenge
In fact, the best candidate for reverse engineering is often determined by market demand for the part. Reverse engineering does not copy an identical twin to the original part because it is technically impossible.
Analysis and Verification
Accreditation
ISO 9001 is a set of documents that define the requirements for a quality management system (QMS) standard. ISO 9001 certification does not guarantee the quality of finished products; rather, it confirms that consistent engineering processes are being used.
Part Criticality
The precision and tolerance required to reverse engineer a part is often determined by the criticality of the part. The service environment also plays an important role in determining the essential characteristics of work.
Applications of Reverse Engineering
Software Reverse Engineering
Reverse engineering will, step-by-step, represent the system at a progressively higher level of abstraction. Software reverse engineering defines the system architecture with the elements of the generic product structure, and identifies the technical requirements for the overall system.
Applications of Reverse Engineering in the Life
The application of reverse engineering offers a less expensive and more comfortable treatment in orthodontics. Applications of reverse engineering in orthopedics, such as knee, hip, or spine implantation, are very challenging, in part because of the complex motions of the knee, hip, or spine.
Surface and Solid Model Reconstruction
- Scanning Instruments and Technology
- Principles of Imaging
- Cross-Sectional Scanning
- Digital Data
- Computational Graphics and Modeling
- Data Refinement and Exchangeability
Each of these triangles is defined by the (x, y, z) coordinates of the three vertices and the normal vector to the surface. The quality of the digital data and the subsequent accuracy of the newly discovered work are critical to reverse engineering.
Dimensional Measurement
Using IGES, a CAD user can exchange product data models in the form of circuit diagrams, wireframe, freeform surface, or fixed model views. The reverse engineering data from an actual measurement shows a bolt hole diameter of 0.510 inch, while the OEM data not available to the reverse engineer shop shows a diameter of 0.500 inch.
Case Studies
The scan data was used to reverse engineer a CAD model of the aircraft. With each scan, the ATOS software responds with information about the quality of the scan and the fit of the scan patch in the global reference system.
Part Tolerance
In reverse engineering, dimensional tolerances are determined by variations in the sample measurements and accepted engineering practices. The fundamentals of engineering statistics and their applications in data analysis of dimensional measurements and property evaluation will be discussed in Chapter 6.
Prototyping
Additive Prototyping Technologies
The accuracy of the final part of the model is directly related to the thickness of the cutting layer. However, most additive prototyping technologies do not provide any information about the machinability of the parts and the manufacturability of the design.
Subtractive Prototyping Processes
Rapid Injection Molding
If the part is cast with the design material, the molded part is practically a first article of the production part that not only provides a sample for performance evaluation, but also provides valuable manufacturability information for future production.
Steps of Geometric Modeling
Theoretically speaking, we can claim that two materials are "the same" only when all their properties have been compared and found to be equivalent. An accurate Young's modulus is usually measured by an ultrasonic technology without applying any mechanical force to the material.
Alloy Structure Equivalency
Structure of Engineering Alloys
The single crystal Ni-base superalloy was developed for turbine blades and impellers in modern aircraft engines. Compared with its counterpart with equiaxed grains, a single-crystal jet engine turbine airfoil can have many times better resistance to corrosion, and much better creep strength and thermal fatigue resistance.
Effects of Process and Product Form on Material
The first single crystal blade aircraft engine was the Pratt & Whitney JT9D-7R4, which was certified by the FAA in 1982. The effects of microstructure on the properties of engineering alloys will be discussed in detail later.
Phase Formation and Identification
- Phase Diagram
- Grain Morphology Equivalency
- Recrystallization, Secondary Recrystallization, and
- Grain Size and Grain Growth
The ASTM (ASTM, 2004) defines the average number of grain sizes in the exponential form described by Equation 3.3. Or the average grain size can be estimated with a linear interception method known as the Heyn method.
Mechanical Strength
- Classic Mechanics
- Critical Resolved Shear Stress
- Fracture Strength
- Material Toughness
- Notch Effects
- Bending, Torsion, and Hoop Stress
For engineering purposes, the yield strength is usually defined as the stress that will cause a small amount of permanent deformation, such as 0.2%, the so-called 0.2% offset yield strength. The maximum stress at the crack tip due to stress concentration is given by equation 3.16 (Inglis, 1913):
Hardness
Hardness Measurement
It shows the indentation on the screen and the hardness measurement data process in the computer. Given the complexity and variance of hardness measurements, it is essential that hardness numbers are measured on the same scale as specified in the reference material specification for direct comparison.
Hardness and Tensile Strength Relationship
These limitations are explicitly defined by the mandatory replacement of the part at a certain time or implicitly defined by the need for regular inspections according to the maintenance manual. This life limitation is due to the fact that some properties of the material and thus the performance of the work made of this material depend on time.
Part Failure Analysis
The maximum shear stress or Tresca criterion indicates that yielding occurs when the maximum shear stress reaches the shear stress value of the uniaxial tensile test. A deep understanding of the functionality and operation of a part design is critical to reproducing an equivalent mechanical component using reverse engineering.
Fatigue
The S-N Curve and High-Cycle Fatigue
The critical minimum stress below which fatigue failure does not occur is defined as the fatigue endurance limit. Basquin's equation can also be modified as Equation 4.10 to include the effect of mean stress.
Low-Cycle Fatigue
For example, shot peening introduces residual compressive stress to the part surface, lowers the average tensile stress and therefore improves the fatigue life of the part. The most common method of presenting LCF data is to plot the range of plastic strain, Δεp, or the range of total stress, Δε, vs.
Component Low-Cycle Fatigue Life Prediction
The estimated component LCF lifetime varies depending on the lifetime prediction method used. For a damage tolerant structure, the component LCF test will run to three times the LCF life target.
Effect of Mean Stress on Fatigue
This master Goodman diagram is useful for predicting fatigue life with any two independent parameters. The fatigue life can be estimated as approximately 3 × 104 cycles by determining the intersection of the two lines of constant σmin = 20 ksi and R = 0.2 in Figure 4.7.
Fatigue Crack Propagation
Their inclusion as the ordinate and abscissa coordinates in Figure 4.7 makes the fatigue life analysis easier, especially for those unfamiliar with the terminologies used in fatigue analysis, such as R or A ratio. The metrics that come from the crack origin are clearly visible on the fracture surface in Figure 4.9a.
Thermal Mechanical Fatigue and Fatigue Initiated
The persistent damage during the fatigue life is primarily due to wear of the part itself, such as reduction of dimensions, rather than from surface defects due to erosion. Mechanical spalling occurs at high stress contact points, such as the contact in a ball bearing.
Fatigue and Tensile Strengths
The effects of residual stress on fatigue and tensile strength are also different. Most notably, the compressive residual stress caused by shot peening is very beneficial to fatigue strength.
Creep and Stress Rupture
High-Temperature Failure
The tension fracture test is very similar to the creep test, except that it is tested at a higher load to cause failure in a shorter time. The stress fracture test data is usually presented with a plot of stress versus fracture time at a specific temperature on a logarithmic scale, as illustrated in Figure 4.15.
Larson–Miller Parameter (Prediction of Long-Term
A Larson–Miller master curve can be established for a given material with experimental data obtained over a range of temperature T and time t. In reverse engineering, the lack of a master alloy-specific Larson–Miller parameter curve, such as Figure 4.17, is also often a challenge for engineers.
Creep Mechanisms
This phenomenon reflects both the importance and complexity of grain size effects on mechanical strength in reverse engineering. In reverse engineering, the same grain size should be required to demonstrate equivalence between the performance of the duplicated part and the OEM part.
Environmentally Induced Failure
- Classification of Corrosion
- Environmental Effects and Protection
- Aqueous Corrosion
- Stress Corrosion
- Oxidation and Protective Coating
- Hot Corrosion
- Metal Embrittlement
Uniform or general corrosion is characterized by corrosive action that occurs uniformly over the entire or most of the surface. However, environmental impact assessment is probably one of the most time-consuming and expensive reverse engineering tasks.
Material Specification
Contents of Material Specification
One of the most challenging tasks in reverse engineering is decoding the original equipment manufacturer's heat treatment plan. It is further complicated by the fact that often several different heat treatment programs can result in similar material properties, but none can provide exactly the same properties as the OEM part.
Alloy Designation Systems
Composition Determination
- Alloying Elements
- Mass Spectroscopy
- Inductively Coupled Plasma–Atomic Emission
- Electron Specimen Interaction and Emission
- X-Ray Analysis
In inelastic scattering, energy is transferred to other electrons in the sample, and the kinetic energy of the incident electron is reduced. This interaction results in a loss of energy and a change in the path of the incident electron, as well as the ionization of an electron in the sample atom.
Microstructure Analysis
- Reverse Engineering Case Study on Ductile Iron
- Light Microscopy
- Scanning Electron Microscopy
- Transmission Electron Microscopy
More comparative analysis is needed to confirm the quality and properties of the nodular cast iron used for the OEM part. Secondary electrons are used to image the morphology and surface topography of the samples, as shown in Figure 5.11a and b.
Manufacturing Process Verification
- Casting
- Product Forming
- Machining and Surface Finishing
- Joining Process
- Soldering
- Brazing
- Welding
- Heat Treatment
- Specification and Guidance for Heat Treatment
- Surface Treatment
- Surface Heat Treatment
- Coating
- Shot Peening
For example, Figure 5.15 shows the macrostructure of the aluminum base for an electric power transmission pole. The directivity of the microstructure in Figure 3.1b further implies that it was processed by extrusion or some other similar product-forming process.
Statistical Analysis
Statistical Distribution
Statistical Parameter and Function
Data Analysis
Statistical Confidence Level and Interval
Sampling
Statistical Bias
Reliability and the Theory of Interference
Prediction of Reliability Based on Statistical
Weibull Analysis
Data Conformity and Acceptance
Dimension and Tolerance
Data Acceptance
Source of Data
Statistical Regression and Relations between
Data Report
Performance Criteria
Test and Analysis
Environmental Resistance Analysis
Methodology of Performance Evaluation
Test Parameter
Test Plan
Probabilistic Analysis
System Compatibility
Functionality
Interchangeability
Cumulative Effect
Case Studies
Fastener Evaluation
Door Stairs
Regulatory Certification of Part Performance
Legality of Reverse Engineering
Legal Definition of Reverse Engineering
Legal Precedents on Reverse Engineering
Patent
Copyrights
Copyright Codes
Legal Precedents on Copyrights
Trade Secret
Case Study of Reverse Engineering a Trade Secret
Third-Party Materials
