Design Analysis – FEA, CFD, and Mold Flow Analysis

Over the years, the term “Design Analysis” has been essential in the manufacturing sector. Instead of making a prototype and creating elaborate testing regimens to analyze the physical behavior of a product, engineers can evoke this information quickly and accurately on the computer.

Design analysis is a specialized computer software technology designed to simulate the physical behavior of an object.

If an object will break or deform or how it may react to heat are the sort of queries design analysis can answer. Design analysis helps in minimizing or even eliminating the need to build a physical prototype for testing. As a result, the technology has gone mainstream as a prized product development tool and found its presence in almost all engineering sectors.

This article discusses three major design analysis software, namely:

• Finite Element Analysis (FEA)
• Computational Fluid Dynamics (CFD)
• Mold Flow Analysis

Finite Element Analysis (FEA)

The Finite Element Analysis (FEA) is a specialized simulation of a physical entity using the numerical algorithm known as the Finite Element Method (FEM). It is used to reduce the number of physical prototypes and experiments and analyze objects in their design stage to develop better products faster. The term ‘finite’ denotes the limited, or finite, number of degrees of freedom used to model the behavior of each element. Mathematics is used to understand and quantify a physical phenomenon such as structural or fluid behavior, wave propagation, thermal transport, the growth of biological cells, etc. Most of these processes are described using Partial Differential Equations. Finite Element Analysis is one of the most prominent numerical techniques for a computer to solve these PEDs.

FEA will analyze an object in question by breaking its entire geometry into small ‘elements,’ which are put under simulated conditions to see how the elements react. It displays the results as color- coded 3D images where red denotes an area of failure and blue indicates fields that maintain their integrity under the load applied. However, note down that FEA gives an approximate solution to the problem.

FEA is used in problems where an analytical solution is not easily obtained, and mathematical expressions are required because of complex geometries, loadings, and material properties. Engineers also use FEA to reduce the number of physical prototypes, conduct failure investigations and improve component designs. It is also used by forensic engineers to determine stress concentrations in structures and to show alternative designs. Finite element analysis can help analyze fatigue-related failures. Finite element analysis has numerous other applications. Its advantages are many – it enables engineers to make better products faster. By breaking down a complex object into thousands or hundreds of thousands of finite elements, finite element analysis predicts how a given object will respond under a certain load. Furthermore, it helps forensic engineers confirm the stress concentrations in a case and show possible alternatives. FEA is also helpful for fatigue-related failure analysis.

Computational Fluid Dynamics (CFD)

Computational Fluid Dynamics (CFD) is a specialized simulation that analyzes fluid flows through an object using numerical solution methods. CFD incorporates applied mathematics, physics, and computing software to evaluate how a gas or liquid flows and how it affects an object as it flows past. CFD is based on Navier-Stokes equations which describe how a moving fluid’s velocity, temperature, pressure, and density are related.

Aerodynamics and hydrodynamics are two engineering streams where CFD analyses are often used. Physical quantities such as lift and drag or field properties as pressures and velocities are computed using CFD. Fluid dynamics is connected with physical laws in the form of partial differential equations. Engineers transform these laws into algebraical equations and can efficiently solve these equations numerically. The CFD analysis reliability depends on the whole structure of the process. Determining proper numerical methods to develop a pathway through the solution is highly important. The software which conducts the analysis is one of the key elements in generating a sustainable product development process, as the number of physical prototypes can be reduced drastically.

CFD is used in almost all industrial domains, such as:

• Food processing
• Water treatment
• Marine engineering
• Automotive
• Aerodynamics
• Aerospace

With the help of CFD, fluid flow can be analyzed faster in more detail at an earlier stage than by testing, at a lower cost and risk. CFD solves the fundamental equations governing fluid flow processes and provides information on essential flow characteristics such as pressure loss, flow distribution, and mixing rates.

CFD injection molding is a widely used manufacturing process for plastic components. It has undergone many improvements over the past few decades, and numerical simulation models enable mold and part design without costly experiments. CFD has become an integral part of the engineering and design domains of prominent companies due to its ability to predict performance of new designs and intends to remain so.

Mold Flow Analysis

Moldflow, formerly known as C-mould, is one of the leading software used in processwide plastics solutions. Mold flow computes the injection molding process where plastic flows into a mold and analyzes the given mold design to check how the parts react to injection and ensure that the mold will be able to produce the strongest and uniform pieces. Using mold flow analysis, a manufacturer can reduce stress levels in its mold and increase filling and product quality. By assessing the flow of the plastic melt, Mold Flow can make informed design decisions and avoid costly mistakes. This software is an invaluable tool to improve quality and increase productivity. This software is beneficial for manufacturers that need to predict the flow of a mold and determine its feasibility.

Two of the most popular mold flow analysis software are Moldflow and Moldex3D, used exclusively by many mold makers.

There are three types of Mold flow analysis which are as follows:

• Moldflow Filling Analysis (MFA): It facilitates visualization of shear rate and stress, as well as determination of fiber orientation and venting. MFA can predict fill patterns and injection pressure while optimizing the gating and runner system.
• Moldflow Cooling Analysis (MCA): MCA specializes in finding hot spots and calculating the time to freeze. It helps determine uneven cooling between core and cavity while specifying required cooling flow rates.
• Moldflow Warpage Analysis (MWA): Moldflow warpage is all about predicting, finding, and determining warpage due to orientation.

To simulate mold flow, a network of rectangular elements is discretized on the mold. The corresponding velocity field is then used to calculate the flow of the melt. A two-stage predictor- corrector method, developed by Hieber and Shen, has been used since then. Mold makers typically use the software Moldex3D, which enables them to visualize the shear rate and fiber orientation in a mold and predict the fill pattern to improve the gating and runner systems.

Importance of CAE in design analysis

Using computer-aided engineering (CAE) software to simulate a mold’s flow can help ensure that it produces a quality product. This simulation software allows engineers to understand how a material reacts to various processing conditions, such as post-processing shrinkage and structural response. The pattern and temperature of the material in a mold are highly correlated with its properties. Using CAE, engineers can solve problems related to the design of a product’s internal structure, such as curing temperature and warpage. In addition to mold flow analysis, CAE software is also used to simulate other processes. Manufacturing companies use CAE software to determine the optimal material flow in a mould. With computer technology advancing rapidly, CAE is becoming an essential tool for manufacturers. Its high-resolution capabilities allow engineers to accurately model the design, eliminate the need for costly prototypes, and simulate its functionality. The software is more accurate and enables engineers to make decisions much faster.

We can see the benefits of using different analysis procedures that correctly understand the power of the different simulation tools. During the product design, many of these methods affect the cost and quality of the product, thereby ensuring optimum productivity as the manufacturer aims.