As computer-aided engineering tools continue to penetrate new segments of the engineering function, the concern has arisen that engineers are becoming too far removed from the basic engineering techniques upon which these tools are based. The most sophisticated analysis tool is only as good as its input and is capable of producing incorrect results given relatively small input errors. Another concern is that many problems that are presently being addressed with complex analysis tools could be solved in much less time given a fast method of solving the closed form equations. As a result, there is a growing "back to basics" movement in the engineering community. The purpose of the back to basics movement is to develop an engineering philosophy which will insure that regardless of the sophistication of the tools that they are using, engineers remain aware of the basic laws of nature which lie at the root of all engineering calculations.

Of course, companies don't necessarily want their people wasting time actually performing hand calculations. Prior to the proliferation of computer-aided engineering technology, no task was as common in engineering as reaching for a reference manual or handbook, searching through it to find a selection that applied to the task at hand, selecting a series of formulas, generating equations and then solving them with a calculator. This entire process could easily take one to four hours. To avoid this time-consuming process, many companies are using computerized engineering handbooks, which incorporate solutions to structural/mechanical engineering applications found in many reference books. In a minute or two, the computer tool provides basic force, stress and deflection calculations which determine whether or not the more detailed results provided by the full analysis are reasonable. The program can also be used to substantially reduce modeling and analysis time and expand on the results provided by the original analysis.

Perhaps the major reason for the back to basics movement involves the increasing reliance which many companies are placing upon finite element analysis and related computer aided engineering techniques. The technology of finite element analysis (FEA) is used universally to calculate stress and deflection of mechanical structures. Unfortunately, finite element analysis can easily produce misleading or incorrect results if the problem is incorrectly formulated. At many companies, finite element analysis has largely replaced hand calculations over the last decade and substantially reduced the amount of physical testing performed as well. Some of these companies have become concerned that their dependence upon finite element analysis raises the risk of product failures in the situation where the finite element problem is incorrectly formulated. The risk of error is increased by the fact that the reduced use of closed form equations means has meant that many engineers have "unlearned" this technique and thus have lost the benefit of an important checking tool. Even in the situation where engineers have maintained their expertise in closed form equations, the time involved in formulating and solving these equations often makes checking impractical.

For these reasons, many engineers have turned to the new generation of computerized engineering handbooks as a finite element analysis input preparation and verification tool. In a minute or two, these new computer tools provide basic force, stress and deflection calculations which determine whether or not the more detailed results provided by the full analysis are reasonable. These handbooks can also be used to substantially reduce modeling and analysis time and expand on the results provided by the original analysis. In most cases, the program will do the equation substitutions, integration, and boundary condition analysis in exactly the way an engineer would solve the problem by hand. In some of the more complicated analyses, the computerized handbook uses finite elements to obtain a solution; however, the input and output format remains similar to the other modules and the user is not required to know finite element techniques. Moreover, once a problem is accurately set up and modeled, it can be quickly changed and rerun to allow the user to look at various options or modifications.

The key benefit of this type of tool is that it keeps the engineer close to the roots of the finite element calculations. The engineer has the opportunity to validate these results at any time by solving close form equations in just a few minutes. The benefits of the use of such a tool, however, go well beyond simply results checking. Judicious use of this type of tool prior to finite element analysis can significantly reduce analysis and modeling time and produce more accurate results. Going one step further, the computerized handbook can be used to quickly perform a parametric study of a component to get a better understanding of the effect of various dimensions and features on its mechanical properties. Often, this leads to pre-analysis design changes, which greatly reduce the number of iterations required. The time to perform finite element analysis can often be dramatically reduced by analyzing section properties prior to performing the analysis.

Here are some examples of the types of analysis that can be performed with a computerized engineering handbook called The Desktop Engineer. The Properties of Plane Sections module computes the area, centroid location, moments of inertia, radii of gyration, shear center, shear area, reduction factor and torsional properties of thirty typical cross-sectional shapes. The Properties of Three-Dimensional Solids module computes the volume, centroid and mass moments of inertia about various axes for typical three-dimensional solids. The Neutral Axis Shift Due to Beam Curvature module computes the shift in neutral axis location, the change in extreme fiber stress, as well as the stress distribution profile when a curved beam is subjected to pure bending.

The Single Span Beams Under Transverse and Axial Loads module computes the deflection, shear and moment along a single beam span. The Single Span Beams Under Torsional Loading module computes the angle of twist, the first derivative of the angle of twist, and the twisting moment along a single span beam. The Multi-Span Beams Under Transverse Loading module computes the deflection, shear, and moment along each span of a multi-span beam. The Curved Beams module computes the deflection, bending and role slopes, transverse shear as well as bending and torsional moments at a set of points along a single span curved beam. The Beams on Elastic Foundations modules compute the deflection, shear and moment along a finite or infinite length beam supported on an elastic foundation. The Lateral Buckling of Beams module computes the critical load for beams that are laterally unsupported. The Buckling of Columns module computes the critical buckling load of columns with various boundary conditions subjected to compressive loading.

An example of the use of a computerized handbook to save time prior to analysis is provided by General Electric Nuclear Energy, San Jose, California. The task is to qualify the control panels and equipment in the control room of a nuclear power plant to ensure their structural integrity and operability. Some of the computational tools used in performing this function at GE are advanced finite element codes such as NASTRAN, ANSYS, SUPERSAP and STARDYNE. The structures involved contain a wide variety of complex sections, which would not be practical to incorporate directly into a finite element model because they would significantly increase both modeling and solution time. Standard procedure in the past was to calculate section properties by searching through a reference manual or handbook to find the section property formulas, generating equations to combine properties for section components, and then solving them with a calculator.

For a typical corner post of a control panel, comprised of angles, channels, unistruts and rolled plate elements, the required calculations would include finding the neutral axis for each element, using the parallel axis theorem to find the neutral axis for the entire section, then calculating the moments of inertia, section areas and other section properties. This process typically took about an hour to calculate and verify for a typical section. With the computerized handbook, all that is essentially required is to enter the dimensions of the various sections -- the program calculates the required section properties. This typically takes less than 5 minutes. The ability to obtain results this quickly has made it possible to perform parametric studies, which allow GE to evaluate far more design alternatives than were previously possible. Aside from time savings, another major advantage of the handbook is that it automatically provides complete documentation of all of the calculations that were performed.

After a finite element analysis has been completed, the closed-form solutions produced by the computerized handbook can be used to verify the accuracy of the FEA analysis. Normally verification is performed with hand calculations that take somewhere between 30 and 60 minutes. The same task can be accomplished in 5 to 10 minutes with a computerized handbook with less chance of error. In addition to verifying the overall structural analysis, the computerized handbook can be used to enhance analysis results. For example, in most cases with a global finite element analysis, it is difficult or impossible to closely examine the loading on individual members of the structure. A computerized handbook can take the internal loading generated by the analysis as well as external loads and apply them to a single beam or other member. A parametric study can be performed to determine the optimum sectional dimensions. In a similar way, the handbook can be used to examine details, which may not be included in the analysis -- for example stress concentration around an opening. It can also be used to quickly perform other types of analysis which may not otherwise have been performed such as calculating natural frequencies of the structure. Finally, multiple loading conditions can be examined in far less time than would be required to incorporate them in the finite element model.

By returning back to basics, engineers will regain their familiarity with the basic laws of nature, prevent errors by validating more complex forms of analysis, and save time by performing calculations on relatively simple geometry in less time than more complex analysis tools.

The equation-solving tools used by this philosophy provide a practical tool in the hands of the professional engineer, a teaching aid in the hands of the educator, an exciting means of learning in the hands of the student, a constructive time-saver for the researcher, and a comprehensive source of information for the designer.