Static calculation of the street lamp in different load cases

Modern road lighting is an important issue for every city, as its function ensures greater safety of pedestrians, drivers and other users of public areas. There is an increased usage of modern LED lamps, which raise the good name of howsoever small cities with their design and low energy consumption. However, every street lamp is subject to a number of natural and weather influences, in which it must operate properly and ensure its function.

At TECOS, we performed a static calculation of the street lamp for the client with the help of computer simulations in the Abaqus CAE software package. The client wanted to test the load capacity of the lamp in various load cases and different temperatures.

17-08-01 luminaire 01

Figure 1: CAD-model of the lamp

Addressed issues

  • The street lamp is exposed to a wide range of temperature loads, in which it has to withstand mechanical loads and provide its function.
  • Due to different weather conditions, the lamp must withstand mechanical loads due to the influence of wind, snow, etc.
  • At increased temperatures and lasting loads, the problem of crawling of the material may also occur.

Solution

For our client, we performed the following steps:

  • definition of five different load cases,
  • determination of temperature-dependent non-linear material data,
  • arrangement of a numerical model and parametric calculation of load cases,
  • presentation of displacements, stresses and deformations on individual components of the lamp and analysis of crawling of the material.

Based on the results of parametric computer analyses, it was possible to determine the tensions on individual components, to anticipate critical points and to foresee the most unfavourable load case. Unfortunately, due to the confidentiality of the project, we can not give specific numbers, for which we sincerely apologize to the readers.

Purpose and benefits for end customers

  • Critical points on the product can already be anticipated at a development stage.
  • Design optimization for weight reduction and life-span extension of the product.
  • Reduced risk in construction and assurance of product's proper functionality.

Determination of load cases

Based on the standards, we first identified five load cases with which the lamp can be loaded, separating them into winter and summer cases. In all cases, the main load is the consequence of the wind, and in the winter time also the load due to snow weight can occur. For each load case we can observe a change in the size and direction of the wind force, which is determined based on the anticipated geographical position of the lamp. In particular, the load case of crawling was discussed, with anticipated long-term loads at increased temperatures.

Various materials, both metal and polymeric, were foreseen for lamp components. For each material, material features were given at -10 °C and at 60 °C. The features at intermediate temperatures were determined based on interpolation. The figure shows temperature-dependent material features for the selected polymeric material.

17-08-01 luminaire 02

Figure 2: Engineering curves of tension due to deformation for the selected material

Based on parametric computer simulations in the Abaqus CAE software package, the greatest displacements and tensions on the lamp occur in the winter load case, which takes into account the combination of the lamp's own weight, lateral wind and snow. At this load, the value of the sagging at the far edge of the lamp exceeded the acceptable value for ensuring the functionality of the lamp; in some places, the tensions exceeded the maximum acceptable tensions, which can result in permanent damage or destruction of individual components. Using numerical results, we thus evaluated the anticipated construction of the lamp.

17-08-01 luminaire 03

 Figure 3: Illustration of displacements in winter time load case 

In analysis of crawling of the material, additional material data were used to illustrate the relaxation of the tension or the deformation increase at constant load as a function of time. The figure shows the crawl curves for the selected material at different tensions.

17-08-01 luminaire 04

Figure 4: Crawl curves for the selected material

Based on the analysis of the crawling, it is possible to predict the deformation increase at a constant load over a longer period of time. It turned out that when considering its own weight and additional vertical load, the value of the lamp's sagging does over ten years not increase to the extent that this value would represent a critical difference.

17-08-01 luminaire 05

Figure 5: Illustration of displacements due to the crawling  

Conclusion

With advanced parametric computer simulations in the Abaqus CAE software package, we managed to anticipate the sagging, deformations, and tensions on individual component pieces of the lamp in various load cases. Such an approach is very important in modern engineering practice, since the client has already been alerted to critical points during the product development phase and suggested some construction solutions that would ensure the product's smooth functioning. If you are interested in actual values and selected load cases, we can contact you directly with the client. 

Why choose TECOS?

  • Vast Experience
  • Highly Trained Staff
  • Short Response Time
  • One Contact For All Your Problems
  • State-of-the-art Equipment

Prijava eseznam Tecos