To begin the new year, and for those of you who are unaware of everything that SolidWorks Simulation software has to offer, I have put together a list of the different types of studies you can perform on your designs. I have also included a brief description of each. SolidWorks Simulation software offers the following types of studies, depending on the software bundle you have purchased. Please consult your FISHER/UNITECH account manager if you have any questions as to what version of SolidWorks Simulation that you currently own.
- Static (or Stress) Studies - Static studies calculate displacements, reaction forces, strains, stresses, and factor of safety distribution. Material fails at locations where stresses exceed a certain level. Factor of safety calculations are based on one of four failure criterion.
Static studies can help you avoid failure due to high stresses. A factor of safety less than unity indicates material failure. Large factors of safety in a contiguous region indicate low stresses and that you can probably remove some material from this region.
- Frequency Studies - A body disturbed from its rest position tends to vibrate at certain frequencies called natural, or resonant frequencies. The lowest natural frequency is called the fundamental frequency. For each natural frequency, the body takes a certain shape called mode shape. Frequency analysis calculates the natural frequencies and the associated mode shapes.
In theory, a body has an infinite number of modes. In finite element analysis (FEA), there are theoretically as many modes as degrees of freedom (DOFs). In most cases, only a few modes are considered.
Excessive response occurs if a body is subjected to a dynamic load vibrating at one of its natural frequencies. This phenomenon is called resonance. For example, a car with an out-of-balance tire shakes violently at a certain speed due to resonance. The shaking decreases or disappears at other speeds.
Frequency analysis can help you avoid failure due to excessive stresses caused by resonance. It also provides information to solve dynamic response problems.
- Buckling Studies - Buckling refers to sudden large displacements due to axial loads. Slender structures subject to axial loads can fail due to buckling at load levels lower than those required to cause material failure. Buckling can occur in different modes under the effect of different load levels. In many cases, only the lowest buckling load is of interest.
Buckling studies can help you avoid failure due to buckling.
- Fatigue Studies - Repeated loading weakens objects over time even when the induced stresses are considerably less than allowable stress limits. The number of cycles required for fatigue failure to occur at a location depends on the material and the stress fluctuations. This information, for a certain material, is provided by a curve called the S-N curve. The curve depicts the number of cycles that cause failure for different stress levels. Fatigue studies evaluate the consumed life of an object based on fatigue events and S-N curves.
- Thermal Studies - Thermal studies calculate temperatures, temperature gradients, and heat flow based on heat generation, conduction, convection, and radiation conditions. Thermal studies can help you avoid undesirable thermal conditions like overheating and melting.
- Design Studies - Optimization design studies automate the search for the optimum design based on a geometric design. The software is equipped with a technology to quickly detect trends and identify the optimum solution using the least number of runs. Optimization design studies require the definition of the following:
- Goals or Objectives. State the objective of the study. For example, minimum material to be used.
- Design Variables. Select the dimensions that can change and set their ranges. For example, the diameter of a hole can vary from 0.5” to 1.0” while the extrusion of a sketch can vary from 2.0” to 3.0”.
- Constraints. Set the conditions that the optimum design must satisfy. For example, you can require that a stress component does not exceed a certain value and the natural frequency to be within a specified range.
- Drop Test Studies - Drop test studies evaluate the effect of dropping the design on a rigid floor. You can specify the dropping distance or the velocity at the time of impact in addition to gravity. The program solves a dynamic problem as a function of time using explicit integration methods. Explicit methods are fast but require the use of small time increments. Due to the large amount of information the analysis can generate, the program saves results at certain instants and locations as instructed before running the analysis.
After the analysis is completed, you can plot and graph displacements, velocities, accelerations, strains, and stresses.
- Nonlinear Studies - When the assumptions of linear static analysis do not apply, you can use nonlinear studies to solve the problem. The main sources of nonlinearity are: large displacements, nonlinear material properties, and contact. Nonlinear studies calculate displacements, reaction forces, strains, and stresses at incrementally varying levels of loads and restraints. When inertia and damping forces cannot be ignored, you can use nonlinear dynamic analysis.
Nonlinear studies can help you assess the behavior of the design beyond the limitations of static and buckling studies.
- Dynamic Studies - Dynamic studies calculate the response of a model due to loads that are applied suddenly or change with time or frequency.
Linear dynamic studies are based on frequency studies. The software calculates the response of the model by accumulating the contribution of each mode to the loading environment. In most cases, only the lower modes contribute significantly to the response. The contribution of a mode depends on the load’s frequency content, magnitude, direction, duration, and location.
The objectives of a dynamic analysis include: (a) the design of structural and mechanical systems to perform without failure in dynamic environments, and (b) the reduction of vibration effects.
