Modelling / 3.3 /
Physical Modelling
Physical Modelling
A physical model is a three-dimensional, tangible representation of a design or system. Designers use physical models to visualize information about the context that the model represents. It is very common for physical models of large objects to be scaled down and smaller objects scaled up for ease of visualization. The primary goal of physical modelling is to test aspects of a product against user requirements. Thorough testing at the design development stage ensures that an appropriate product is developed.
Physical models allow for the presentation of ideas for inspection using potentially all our senses.
Sight or vision
Hearing or audition.
Smell or olfaction.
Taste or gustation.
Touch or tactition.
A physical model can be used to obtain important data such as test and simulation measurements. A model of a physical object presents a means for manipulating the object in order to analyse it fully and get constructive feedback. Physical models can also be quickly and easily altered and modified to react to feedback.
A scale model is a smaller or larger physical model of an object. Scale models are commonly seen in architecture when a full-size building is modelled by greatly reducing the scale. This enables designers, and clients to visualise the structure of the building, but also the exterior and interior aesthetics and lines. Unforeseen factors can be highlighted, and modifications can easily be made before going to full-scale production.
Small-scale models are generally used to express an idea or look at the overall aesthetics and proportions of A product. They are used for a number of products and purposes but tend to be low fidelity and do not express great detail regarding construction methods or use the exact materials of the final product.
Small-scale modelling can be a fast method to develop design ideas, or it can be something far more sophisticated and expensive like an architectural model that is used to communicate design thinking, specific ideas or aesthetic issues.
An aesthetic model is a model developed to look and feel like a real product. They are used to evaluate user appeal or in ergonomic testing. These models do not actually work (they are not prototypes) and are typically not intended to be handled greatly. The primary function is to communicate and test the aesthetic elements of a design or to evaluate the properties of a material:
Weight and balance: using materials similar in weight and density to the final production material, the model could be used to evaluate how heavy a design is, or how it balances. A good example of this might be a hand tool, portable device, or sports equipment.
Texture and surface qualities: finishes, paint, or textures might be applied to the surface to communicate how the surface looks, feels or reflects light.
Mock-ups are full-size models of a product made using inexpensive materials. They have some functionality, meaning that they can also be used as a prototype. Mockups are used to test:
How something works or feels.
Whether something fits into a specific space or room.
Proportions
Colour or finish
When designing a functional product, such as a household device, mock-ups can be used to test whether they suit typical human shapes and sizes. The cost of making mock-ups is often more than repaid by the savings made by avoiding going into production with a design which needs improvements.
A prototype is a sample or model built to test a concept or process or to act as an object to be replicated or learned from. A prototype is a further advancement from the mock-up. A prototype is a simple model built to test, evaluate and validate a design concept. Prototyping is used to provide specifications for a real, working product rather than a theoretical one. It is built to be tested and used in order to provide feedback to the design team from a variety of stakeholders in the product.
Prototypes are often put in the hands of users so that designers can observe how they are used. In this way, designers can gain feedback from the users, and learn more about the design context.
Prototypes can be used to test and refine specifications. They can also be used to help learn more about the design or (challenges to) the manufacturing context.
The fidelity of the prototype is the degree to which the prototype is exactly like the final product. Fidelity is usually classified into three groups:
Low-fidelity models are a conceptual presentation of an idea. They are not tangible or durable, but they do communicate basic information about form, shape, function, etc. Paper prototypes are a good example of low-fidelity prototypes
Mid-fidelity prototypes communicate more about an idea or concept. They may communicate some but not all of the functions of the design.
High-fidelity prototypes attempt to represent as close as possible the functionality of the final product. They are typically durable enough to be testable and used by the user group to gather usability data.
Instrumented physical models are prototypes equipped with the ability to take measurements that provide quantitative data on the performance of a product. They can be used to effectively investigate many phenomena such as fluid flows in hydraulic systems, aerodynamic patterns around cars in wind tunnels, variables such as velocity, force, bending, folding, or torque of a product.
Instrumented physical models contain testing equipment in the model itself and allow data to be logged for analysed whilst the model is in use. The data can later be analyzed and design, manufacture, and safety decisions can be made from it.
Advantages
Multi-sensory evaluation: Allows idea evaluation using all senses.
Explore and test ideas: Some ideas are more easily explorable in physical form compared to other modelling forms (e.g. a flat pack container that is folded out of a single sheet of material). Physical models can often be quickly manipulated.
Easily understandable: a physical representation of an idea, concept or design. Easily understood by non-technical audiences.
Communication: Allow for clear communication with clients and team members about the design. This is especially important when communicating with a non-technical audience
Tangible: it can be put in someone's hands or tested
User testing: Can be easily used in user trials to generate data; Particularly useful when gathering ergonomic data are trying to predict user behaviour.
Disadvantages
Time-consuming; creating models and iteration can be time consuming
Cost: The manufacturing of prototypes can add to the overall cost of the manufacturing of a product.
Environmental cost: Materials and processes used may produce waste or use raw materials that impact the environment.
Skill: A model maker needs to be familiar with the materials or technology used to manufacture the models.
Accuracy: Mistaken assumptions that the model accurately represents the reality of the design context may lead to misinterpretation regarding ergonomics, the performance of materials, functioning, aesthetic appeal etc. However, careful analysis and inquiry can lessen this risk.
Type of Physical Model
Advantages
Use cases
Aesthetic Model
Look like the final model
Evaluate aesthetic appeal
Use to consider color combinations, textures, form, etc.
Get client feedback on aesthetic aspects of a design
Mock-up
Scaled or full-size replica
Communicate form and proportion of a design
Low-fidelity models can be made relatively quickly
Used to gather client feedback
Prototypes
Validate that a design can work as intended
User testing of functionality
Develop and improve the functionality of a design
Instrumented Models
Provide accurate quantifiable data about a design as it is being used or tested
Can provide data in real-time
Understand how physical forces act on a design
Allow for very precise measurement
Evaluate how a design performs under various conditions and forces
Test performance of materials (i.e. impact testing, heat resistance, etc.)
Scale models
Can be larger than the actual design and thus communicate fine details
Can be smaller than the actual design and thus save materials, time, etc, as elements of the design are developed
Used to gather client feedback about a design
If it is a small design like a watch, a larg-scale model can help communicate details that would otherwise not be easy to see
If it is a large design, like a car door, a small-scale model can allow the designer to work out the details of a mechanism without having to invest time and money in producing a life-size model