The SolidWorks Blog

Climbing Ladders With SolidWorks: Don't Just Stress About Strength

I love this time of year in New England--the weather, apple picking, the colors as the leaves turn.  But what I don’t love is the half a trillion leaves that fall into my garden that I then have to blow/rake and pick up.  But they don’t just fall on the ground; they fall into the gutters causing clogs and mini floods the next time it rains.  So last weekend I braved up and got out the ladder to clear them out. 

I’m in a new house, so it’s the first time I have done these gutters, and I was struck by how my extension ladder could be both as rigid as a rock or as flexible as rubber (okay maybe a slight exaggeration), depending upon the angle of the ladder and how much it was extended.  Idle speculation lead me down to my basement office, and in a few short minuntes, I had a test model ready to go in SolidWorks Simulation.  In order to get a more representative result, I also created a model of myself on the ladder, to add some extra weight.

As you can see I used weldments for both the ladder and myself, with my weight set to 190 lbs [you wish - Ed.]. This is because I am not interested in the detailed stresses in the ladder; rather, I want to know why it become so flexible as it extends.  The stiffness of the ladder is related to its natural mode of vibration, so my first test was to see what effect extending the ladder had while keeping the maximum elevation at 4m.

The Three Ladder Configurations tested

Setting up the problem in SolidWorks Simulation was very simple; all you have to do is restrain the ends of the ladder and hit run.  And this is where it gets interesting.  If you look at the first natural mode for the ladder (see below) we can see as the ladder extends the frequency drops, indicating a reduction in stiffness. 

	First Mode	Behavior
No Extension	5.0 Hz	Twisting
Half Extension	4.0 Hz	Twisting
Full Extension	2.7 Hz	Hogging-Sagging

But the real analysis ‘gold’ comes from looking at the mode shapes.  For the ladder with no or only half extension, the first natural mode is a twisting mode, and for the fully extended ladder it is a hogging/sagging mode.

The reason this is important is because this mode is excited by the movement of a person up the ladder.  So the greater the force in the excitation direction, the greater the movement of the ladder.  The amount of twisting force applied as you go up a ladder is relatively small as at the most you weight moment arm is half the width of the ladder, but the force in the last case is well aligned to the natural mode so even if you do not move up the ladder one step every 1/3 of a second to induce resonance, the ladder will tend to move a lot mode due to this force alignment.

So what would happen if I moved up this ladder by two rungs at one rung per second??  To understand this I need to carry out a dynamic analysis.  And the results are telling; even though I am away from the first natural mode, the ladder will flex at a peak of 35mm, but when I stop moving, the movement quickly dies away.

So what have I learned from this simple test?  Firstly, don’t just consider strength; if the operational load moves or varies, look at the flexibility of you design.  A frequency study can qualitatively tell you how flexible your design is, but a dynamic analysis will tell you exactly how your design will perform under variable loads.

I also learned that I hate ladders, and that the local handyman can clear out my gutter next time..

Want to see how SolidWorks Simulation applies to more real-world situations? Check out our Simulation Screencasts:

Ready to build a business case for SolidWorks Simulation? Our online calculator gives you a personalized cost savings report in minutes.

Big Ass Fans Move Big Volumes of Air With Help from SolidWorks

Whether you’re trying to cool off your living room, restaurant, industrial plant or business, you’ll probably need a “big ass fan” to circulate high volumes of air and get the job done right. Big Ass Fans, a Kentucky-based manufacturer, produces high-volume, low-speed ceiling and vertical fans with a sleek design. To decorate your home, for example, Big Ass Fans offers the Haiku, a fan with a minimalist look that’s 80% more efficient than other small ceiling fans. For larger rooms and small commercial spaces, the stylish Isis may be a better fit and, despite its diameter of up to 10 feet, this fan weighs less than 100 pounds. How does Big Ass Fans create a product that can move air in spaces ranging from small rooms to large industrial spaces? The answer is simple: SolidWorks.

After using AutoCAD software and 2D design techniques to produce fans for industrial applications, Big Ass Fans decided to make the switch to SolidWorks to expand their business into commercial and residential markets to increase efficiency and improve development. As a result, the manufacturer cut design cycles by up to 50 percent. SolidWorks Simulation enabled Big Ass Fans to streamline production through rapid prototyping. From a design, simulation, and manufacturing perspective, the software addresses all of the company’s needs: from fabrication to making aluminum castings and plastic injection-molded parts.

Using SolidWorks, Big Ass Fans created a product that generates energy savings for an eco-friendly and wallet-friendly environment. Before cranking the heat this season, consider installing a Big Ass Fan to be comfortable in your space.

Read more about how SolidWorks and Big Ass Fans can help you do that in a case study on the SolidWorks website.

Nexxt Spine is developing the next generation of spinal implants with SolidWorks

A few weeks ago Richard Doyle and I were attending some SolidWorks User Group meetings in the American Midwest. Whenever I go on a tour like this, I like to spend the day visiting with SolidWorks customers in the area. During my most recent trip, I met with a very interesting SolidWorks customer called Nexxt Spine, located in Indianapolis, Indiana.

Nexxt Spine creates spinal implants and instruments for the medical community. They focus on creating products that are both high-performance and easy to use. Most of their implants are made to screw directly into vertebrae and other bones connected to the spinal column, and all are manufactured in their own facility in Indianapolis.

While I was visiting, the team at Nexxt Spine actually let me try out the practice system designed for spinal surgeons. As you can see in the image below, they let me use one of their precision instruments to screw an implant into a simulated bone.

Maximize your punkin' chunkin' catapult with SolidWorks Simulation

Have you ever wondered how far you could throw a pumpkin? No? Me neither. However, a lot of people not only give this significant thought, they also meet in a big field to test their weird and wonderful contraptions at the Punkin' Chunkin' World Championships.

In a nutshell, teams compete to see how far they can launch a pumpkin by catapult, trebuchet, or air cannon. I first learned about this weird and wonderful completion a while ago, and I decided that rather than build my own physical catapult and test it, I would do the smart thing--build and test it in SolidWorks first.  Now, I didn’t want to spend a ton of time creating a detailed model to test; I just wanted a quick and dirty model that I could use to test my design hypothesis and make some initial determinations, namely:

1. What beam sections to use on the design?
2. Where to put the arm stop?
3. What are the impact stresses?
4. How far would the pumpkin go?

So my first design was quite basic, but it still had enough detail to provide meaningful design data. This is a really important point for any design analysis: analyze early and often to get the maximum benefit.

How POLYRACK Makes Its Products “Cool”

Complex technologies, such as desktop computers, involve many different components that have the tendency to overheat, including multiple printed circuit boards. How do you measure the impact of electricity and heat running through your product? POLYRACK Tech-Group employed the help of SolidWorks Flow Simulation for integrated packaging solutions that address heat transfer challenges in computers and electronics.  Prior to using SolidWorks, POLYRACK struggled to optimize and innovate effective cooling systems for racked electronic systems and components.

Electronics packaging provider POLYRACK uses SolidWorks Flow Simulation software and its Electronics Cooling Module to resolve heat transfer challenges related to its packaging designs.

After using SolidWorks Flow Simulation to evaluate its design and measure heat transfer and fluid flow, POLYRACK Tech-Group reduced development time from three months to two weeks. The software allows POLYRACK to quickly simulate airflow and address the heat transfer issues rather than going through expensive prototyping. Adding the system’s Electronics Cooling Module, POLYRACK extended the software’s capabilities for handling heat transfer problems related to multicore chips and heat pipes. As a result, POLYRACK cut two prototyping cycles out of their production process.

SolidWorks Flow Simulation showed POLYRACK that it could use four large cooling fans as opposed to eight on a housing with 10 different highly integrated boards. To learn about some of the other problems that SolidWorks helped POLYRACK address, read the case study.

Safe Offshore Equipment with Leenaars Marine and Offshore Design BV

Construction of offshore platforms can often be costly and dangerous considering weather conditions and the possibility of drops into the cold ocean. For reliable and innovative vessels and equipment designs, the industry turns to Leenaars Marine & Offshore Design BV. With over 30 years of experience in the maritime industry, Leenaars BV has worked with international partners on notable research projects. To reach its design goals, the firm enlisted the help of SolidWorks.

Leenaars Marine & Offshore Design relies on SolidWorks Premium integrated analysis tools to optimize the structural performance of its designs.

Using SolidWorks Premium, Leenaars BV conducted in-depth analysis with SolidWorks Simulation. Switching to SolidWorks from an independent contractor allowed the company to shorten the design time by up to 50 percent and doubled the productivity of the engineers by opting for in-house design analysis. The product development time was optimized as a result of shorter communication cycles and the ability to test a large number of variations with the software.  Leenaars BV reduced building costs by $450,000 and 10 lost ship days by reducing the amount of steel in the LNG module making it up to 20 percent lighter. By using SolidWorks, the firm not only improved its design process but also improved its use of design models for simulation and presentations.

As a result, Leenaars BV maintains its industry leadership status with the help of SolidWorks. To learn more about how SolidWorks optimizes the firm’s offshore equipment and vessel design and production process, check out the case study.

New in SolidWorks 2013: Simulation Sub-Modeling and Incremental Meshing

These new features in SolidWorks 2013 let you focus on and refine specific areas of a larger multi-body or multi-part structure while automatically applying loads from a larger model for fast, accurate analysis.

• Quickly get detailed simulation results for specific areas of complex models
• Uses a finer mesh in critical areas for refined analysis
• Analyze larger problems using fewer computational resources

You can learn more in the video below, and visit our new SolidWorks 2013 website to learn about the other new features, as well as find a reseller seminar near you.

Assuming Small Displacement: The Large Displacement Flag

SolidWorks Simulation Premium includes a variety of analysis types (click here for full list).

An assumption that Linear Static analysis makes is that the stiffness of the structure remains constant no matter what type of load is being applied. This is usually a good assumption when the displacements are relatively small. But what about in cases when the load is applied in such a way that it causes the stiffness of the structure to change? Fortunately, in most scenarios such as these, the software warns you with the message shown in Figure 1 below.

Figure 1 - Large Displacement Flag (LDF) Dialog

If you click Yes to this message, the software turns on a Large Displacement Flag (LDF) and therefore no longer assumes the stiffness is constant. In order to do this, the software changes the stiffness again and again during the solution process. This usually makes the run-time take at least 5 times longer. In some cases it may take 50 times longer, or it may even fail!

If you click No to this message, then you’ll usually get some results almost instantly after making the selection, but you may have to question their accuracy.

Some questions that come to mind may be:

Is it worth waiting the extra time for a LD solution when I could run small displacement instead? And if the small displacement result looks questionable, won’t I get better results than either of these studies if I run a Nonlinear Static analysis?

The Test

To try to develop some insight into these questions, I decided to run a test on the simple model shown in Figure 2.

Figure 2 - Displacement of thin beam

I designed the thin (0.05in), 10-inch long steel model in such a way that when I applied 1 lb of bending force, I got 1 in of displacement. Therefore the stiffness seemed to be 1lb/in under this type of load. This seems to imply that if I apply 2 lbs I should get about 2 inches of displacement. However, it doesn’t make much sense to say that if I apply 20 lbs I would get 20 inches of displacement. This would seem to mean that the model stretches to be about twice its original length! So it seems apparent that this overall stiffness value should change with the load. Also, the material may yield at some point which is another effect I may need to take account of for certain loads.

I noticed that in this model, the stiffness seemed to change with only a small amount of loading. I ran the study with small displacement and also with the LDF activated and I compared these results. I could see how the stiffness was increasing. A summary of the comparison is shown in the Figure 3.

Figure 3 - Small Displacement vs. Large Displacement

 

I noticed that in this model it took only about 0.3 lbs of force for the LD dialog to pop up, yet about 4-5 lbs were required to get the material to yield. In order to test the influence this yielding had on my model, I decided to run two Nonlinear studies: one with the LDF activated and one with small displacement. These results are compared to the linear Static studies from before in the graphic below.

Figure 4 - Linear vs. Nonlinear

 

Conclusion

If I accept the Nonlinear LD solution as the most accurate solution under all loading up to and beyond the yield point, I may conclude from these studies that as long as my material doesn’t yield, enabling the LDF in Static analysis provides me with good results. On the other hand, if the material does yield, I may want to consider running a Nonlinear analysis.

Also, for many cases, the results between small displacement and large displacement may differ if I continue to increase the load well above the point at which I receive the LDF dialog.

Finally, it is important to note that the results above only directly apply to the thin beam model that I constructed and the curves may look totally different for other models.

***

Shaun Bentley is a SolidWorks Elite Application Engineer at DASI Solutions, a SolidWorks Value Added Reseller with locations throughout Michigan and Indiana. He is a regular contributor to the DASI Solutions Blog.

SolidWorks 2013 has arrived

Every fall, a new version of SolidWorks is unveiled. We’re always really excited about all of the new functionality that goes into every release, and you’ve probably heard that over 90% of enhancements are driven by customer requests. That’s true for 2013 as well, but this year might be a little more exciting than usual.

SolidWorks 2013 includes some really cool new capabilities that customers have been requesting for a while. For example, there are some new geometry tools that will help you create models faster and easier. These include:

• Conic Sketch – This gives you full control over shapes for smooth transitions between existing geometries.
• Intersect Feature – You can quickly add or remove geometry without sketching.
• Varying Dimension Patterns – Helps you save time creating patterns, increases design flexibility, and reduces the number of features needed for models. 
• Section View Assist – Speeds the creation of production drawings for faster and more consistent section views.

There are also some new tools to help you optimize the performance of a SolidWorks installation and maximize design team productivity. These include:

• CAD Administrator Dashboard – This helps simplify management and troubleshooting of multiple SolidWorks users within a company from a single aggregated view.
• Simulation Sub-Modeling and Incremental Meshing – You can more accurately perform precise simulation analysis for specific areas of large and complex models, and do it faster and more efficiently.
• Network Rendering for PhotoView 360 – This helps you save time with faster rendering of photorealistic images by networking multiple computers to share the computational load.

There are also some new tools that help you work and collaborate with other people on your design team, vendors, and other supply chain partners. These include updates for improved connectivity, enhanced viewing capabilities, and expanded sharing of designs and data, such as:

• Previous Release Interoperability – Starting with SolidWorks 2013, you can collaborate with customers, suppliers, and internal teams with the ability to open SolidWorks files directly with SolidWorks 2012 (SP5). Users can work more efficiently and improve collaboration and file exchange, reducing delays and easing the transition to the latest release.
• SolidWorks Enterprise Product Data Management Workflow – Route documents and contact users more efficiently to reduce delays and accelerate time-to-market.
• DraftSight/SolidWorks Enterprise PDM Integration – Access DWG files within SolidWorks EPM from the DraftSight user interface, and leverage 2D into the design process.
• eDrawings — You can measure, select and markup  designs from anywhere using a mobile device

You can learn more about SolidWorks 2013 on our website (no registration required), so go check it out. And if you’re interested in attending a live seminar on SolidWorks 2013, visit: http://www.solidworks.com/launch/find-a-seminar.htm

Bosch Designs Across Industries with SolidWorks Software

Car maintenance is a necessary evil for most car owners – you know you have to do it, but many of us avoid it or put it off until the car needs repair. While going to the auto mechanic may be costly, some drivers still choose to leave that work to the professionals. But those of you who like to tinker may prefer to do job yourself. Either way, you’re probably familiar with Bosch, the world’s largest automotive component manufacturer, because most cars on the road today contain Bosch parts.

However, you might not know that Bosch does other things too. The company also produces technologies for applications as varied as packaging, production, and security solutions; and consumer goods such as home appliances, power tools, and healthcare products. They even make solar energy, thermotechnology, and turbine systems.

To optimize product design and streamline the manufacturing process, Bosch switched to SolidWorks software simulation, 3D CAD and product data management solutions in 1999. As a result, Bosch decreased the time spent on electrical-mechanical design integration by 500 percent and reduced fixture change-out time by 20 percent.

Learn more about how SolidWorks solutions and partner products—such as CircuitWorks/Zuken ECAD integration—are helping Bosch increase automation and productivity in the case study.

If you come across a Bosch product at an auto part store or elsewhere, there’s a good chance that it was optimized for your needs with the help of SolidWorks solutions.