Any product is designed keeping in mind its intended use, the materials available, cost and aesthetic considerations. The design of any product can be bifurcated into two parts:
i. The determination of forces at any location. For example, the joints of a chair that bears the load, the handle of a cup, etc.
ii. The selection of materials and designing the product in such a way that the stresses and deformations developed stay within permissible limits.
Structural analysis essentially means evaluating the product’s structural design under stipulated loads, boundaries, conditions and pressures. It analyses the structural integrity of the product under various circumstances to identify the weak areas or errors in the product design. Once they are isolated, the design fallacies can then be worked upon, and corrected to develop a design that performs under desired circumstances. In other words, the purpose of structural analysis is to keep the axial, torsional, shear, bending and any other internal forces of a product within permissible limits.
Scope of Structural Analysis
The structural analysis process can be broadly classified into three main categories:
Static analysis determines the internal forces and displacements due to time-independent loading conditions.
Stability analysis deals with products that are subject to compressed time-independent forces.
Vibration analysis determines the natural frequencies / eigenvalues and corresponding mode shapes (eignenfunctions) of vibration in the product.
Structural analysis of any product is based on the following assumptions.
1.The product material is completely elastic
2.Superposition principle - any factor caused by different loads that act simultaneously are equal to the algebraic or geometric sum of this factor due to each load separately
3.The deformation of the product caused by the applied loads do not change the original design diagram
4.Relationship between stress and strain is linearEarlier, structural analysis was a tedious chore that involved solving mathematical equations manually. The introduction of CAE software has made structural analysis relatively simple, though it still takes a highly skilled engineer to properly interpret the results.
Structural Analysis – the Process
All structural design services companies start by simulating a geometric model of the product. This model needs to be meshable into a correct finite element mesh. This is done in order to ensure that the CAD geometry will mesh and will provide important data like stresses, displacements or temperature distribution with accepted accuracy. There are three steps involved in this process:
Defeaturing: this step involves removing unwanted geometry features from the CAD model. A few examples of such features are chamfers, holes, outside fillets, etc.
Idealization: This basically means simplifying the CAD model to reduce the analysis time without compromising on the precision of the computed results.
Clean-up: Clean-up is done to ensure that the model geometry satisfies high quality requirements to be mesahble. The structural analysis service team uses CAD quality control tools for this.
Once you create a geometric model of the product, the mathematical model can be split using the process of discretization. The geometry, loads and restraints are all discretized. This process is called as meshing. Simply put, meshing is a discredtized representation of the product’s geometry.
Structural Analysis Services
Structural analysis of a product is an iterative process. The structural analyst creates a discrete geometric model based on the designer's inputs and by using some CAE software tools. The designer then validates the products based on the simulation results. After optimization, the product design is again sent to the structural analyst, and the cycle continues. While a few companies have in-house CAD / CAE designers, they are not in a position to purchase the latest CAE software required for the structural analysis. This is where they outsource the structural analysis process to companies that have this expertise.
India, with a pool of talented manpower, is a key player in the field of structural analysis services.